TUDCA (tauroursodeoxycholic acid)

updated

TUDCA (taurursodiol) is the taurine conjugate of ursodeoxycholic acid. FDA approved it only inside a fixed combination with sodium phenylbutyrate for ALS (RELYVRIO, 29 September 2022) and withdrew approval as of 29 August 2025 after the phase 3 PHOENIX trial missed its endpoints. Randomized trials give narrow human liver data in primary biliary cholangitis and HCV hepatitis, and a PubMed search on 9 October 2026 found no study of TUDCA given alongside an anabolic androgenic steroid.

Taurine-conjugated bile acid

  • FDA approved RELYVRIO (sodium phenylbutyrate and taurursodiol, NDA 216660) on 29 September 2022 and withdrew approval as of 29 August 2025; taurursodiol has never been approved in the US as a single ingredient.
  • EMA refused marketing authorization for the same combination (Albrioza), with refusal recorded on 5 January 2024, and Health Canada lists ALBRIOZA as Cancelled Post Market.
  • In 199 Chinese adults with primary biliary cholangitis, TUDCA was non-inferior to UDCA on alkaline phosphatase response over 24 weeks (75.97% versus 80.88%, P = 0.453).
  • A meta-analysis of 2 randomized ALS trials of the combination (801 participants) found no significant effect on function (mean difference 1.51, 95% CI -1.01 to 4.02) or survival (hazard ratio 0.90, 95% CI 0.73 to 1.11), at very low certainty.
  • A PubMed title and abstract search on 9 October 2026 pairing TUDCA with anabolic androgenic steroid terms returned 3 records, none of TUDCA given with an anabolic steroid in any species.
  • The only human record of TUDCA taken as liver protection is a 2026 case report of drug-induced liver injury that occurred anyway.

What is TUDCA, and what did FDA approve?

TUDCA (taurursodiol) is the taurine conjugate of ursodeoxycholic acid. FDA approved RELYVRIO, a fixed combination of sodium phenylbutyrate and taurursodiol for ALS, on 29 September 2022 and withdrew approval as of 29 August 2025. Taurursodiol has never been approved in the US as a single ingredient.

Tauroursodeoxycholic acid is PubChem CID 9848818 (C26H45NO6S, molecular weight 499.7 g/mol, CAS 14605-22-2). Listed synonyms include TUDCA, taurursodiol, ursodoxicoltaurine, ursodeoxycholyltaurine and UR-906. It is the taurine conjugate of ursodeoxycholic acid (UDCA), which is a separate approved drug and a separate molecule. The FDA-approved product used the dihydrate (C26H45NO6S.2H2O, molecular weight 535.74), so figures taken from that label are dihydrate figures.

FDA approved NDA 216660 for RELYVRIO, a fixed combination of sodium phenylbutyrate and taurursodiol given as an oral suspension, on 29 September 2022 (priority review, type 1 new molecular entity, orphan designation, sponsor Amylyx). The openFDA record read on 9 October 2026 lists the marketing status as Discontinued. Taurursodiol has never been approved in the US as a single ingredient, and a DailyMed drug name search for tauroursodeoxycholic on 9 October 2026 returned no labels.

FDA withdrew approval of NDA 216660 as of 29 August 2025 (90 FR 42251). The notice states that on 30 April 2024 Amylyx reported that the phase 3 PHOENIX trial (Study A35-004), a global 48-week randomized placebo-controlled trial, did not meet its prespecified primary and secondary endpoints; that Amylyx notified FDA on 30 September 2024 of plans to discontinue marketing as of 31 October 2024; that FDA then requested a voluntary withdrawal request under 21 CFR 314.150(d); and that Amylyx submitted that request on 28 February 2025 and waived a hearing. The notice adds that distributing the product in interstate commerce without an approved application is illegal.

PubChem: TUDCA identity, synonyms and dihydrate used in the approved product

Chemical identity record

National Library of Medicine. PubChem compound record CID 9848818 (tauroursodeoxycholic acid).

Tauroursodeoxycholic acid: PubChem CID 9848818, C26H45NO6S, molecular weight 499.7 g/mol, CAS 14605-22-2. Listed synonyms include TUDCA, taurursodiol, ursodoxicoltaurine, ursodeoxycholyltaurine and UR-906. It is the taurine conjugate of ursodeoxycholic acid, which is a separate approved drug and a separate molecule. The FDA-approved product used the dihydrate, C26H45NO6S.2H2O, molecular weight 535.74, so figures taken from that label are dihydrate figures.

Participants / model
Chemical identity, not a clinical population
Treatment
Defined bile acid and its dihydrate
Follow-up
Not applicable
Study design
NLM chemical record
Funding
not stated in the source

Identity record only; it says nothing about efficacy or safety.

Read the original source
Drugs@FDA: RELYVRIO approved 29 September 2022, marketing status Discontinued

Regulatory record

U.S. Food and Drug Administration. Drugs@FDA application record for NDA 216660 (RELYVRIO, sodium phenylbutyrate and taurursodiol), with the openFDA record and a DailyMed drug name search for tauroursodeoxycholic read on 9 October 2026.

FDA approved NDA 216660 for RELYVRIO, a fixed combination of sodium phenylbutyrate and taurursodiol as an oral suspension, on 29 September 2022, as a priority review, type 1 new molecular entity, with orphan designation, sponsor Amylyx. The openFDA record read on 9 October 2026 lists the product marketing status as Discontinued. Taurursodiol has never been approved in the US as a single ingredient, and a DailyMed drug name search for tauroursodeoxycholic on 9 October 2026 returned no labels.

Participants / model
Adults with ALS
Treatment
Oral suspension, fixed combination with sodium phenylbutyrate
Follow-up
Approval of 29 September 2022; status read on 9 October 2026
Study design
FDA application record
Funding
not stated in the source

The approval was for the fixed combination, not for TUDCA alone.

Read the original source
Federal Register, 29 August 2025: approval of RELYVRIO withdrawn after PHOENIX missed its endpoints

Regulatory record

U.S. Food and Drug Administration. Amylyx Pharmaceuticals, Inc.; Withdrawal of Approval of New Drug Application for RELYVRIO (sodium phenylbutyrate and taurursodiol) for oral suspension. Federal Register, 29 August 2025, 90 FR 42251.

FDA withdrew approval of NDA 216660 as of 29 August 2025. The notice states that on 30 April 2024 Amylyx reported that the phase 3 PHOENIX trial (Study A35-004), a global 48-week randomized placebo-controlled trial, did not meet its prespecified primary and secondary endpoints; that Amylyx notified FDA on 30 September 2024 of plans to discontinue marketing as of 31 October 2024; that FDA then requested a voluntary withdrawal request under 21 CFR 314.150(d); and that Amylyx submitted that request on 28 February 2025 and waived a hearing. The notice adds that distributing the product in interstate commerce without an approved application is illegal.

Participants / model
Not a clinical population
Treatment
Oral suspension product
Follow-up
Events from 30 April 2024 to 29 August 2025
Study design
Federal Register notice of withdrawal
Funding
not stated in the source

The withdrawal concerns the fixed combination and the trial result behind it.

Read the original source

What did EMA and Health Canada decide about the combination?

EMA refused marketing authorization for Albrioza (sodium phenylbutyrate and ursodoxicoltaurine) for ALS, with refusal recorded on 5 January 2024. Health Canada lists ALBRIOZA as Cancelled Post Market, so it is no longer marketed in Canada.

EMA refused marketing authorization for Albrioza (sodium phenylbutyrate and ursodoxicoltaurine) for ALS. The initial opinion was issued on 22 June 2023 and confirmed after re-examination on 12 October 2023, with refusal recorded on 5 January 2024. EMA states that the main study in 137 patients did not convincingly show the medicine slowed worsening of the disease, that survival data were not reliable given how they were collected and analyzed, and that a positive benefit-risk balance could not be established.

Health Canada's Drug Product Database record for ALBRIOZA (DIN 02527707, drug code 101675, sponsor Amylyx, prescription schedule) shows an original market date of 29 July 2022 and a current status of Cancelled Post Market with a history date of 23 September 2024. The product is no longer marketed in Canada.

Both records concern the fixed combination, not TUDCA alone. This page states only what the FDA, EMA and Health Canada records say; records for other countries were not reviewed.

EMA: Albrioza refused, opinion 22 June 2023, confirmed 12 October 2023, refusal 5 January 2024

Regulatory record

European Medicines Agency. Albrioza (sodium phenylbutyrate and ursodoxicoltaurine), European public assessment report and refusal record.

EMA refused marketing authorization for Albrioza (sodium phenylbutyrate and ursodoxicoltaurine) for ALS. The initial opinion was issued on 22 June 2023 and confirmed after re-examination on 12 October 2023, with refusal recorded on 5 January 2024. EMA states the main study in 137 patients did not convincingly show the medicine slowed worsening of the disease, that survival data were not reliable given how they were collected and analyzed, and that a positive benefit-risk balance could not be established.

Participants / model
Adults with ALS
Treatment
Oral powder for suspension, fixed combination
Follow-up
Opinion 22 June 2023; refusal recorded 5 January 2024
Study design
EMA benefit-risk assessment
Funding
not stated in the source

The refusal concerns the fixed combination, not TUDCA alone.

Read the original source
Health Canada: ALBRIOZA Cancelled Post Market, history date 23 September 2024

Regulatory record

Health Canada. Drug Product Database record for ALBRIOZA, DIN 02527707, drug code 101675, sponsor Amylyx.

Health Canada's Drug Product Database record for ALBRIOZA, DIN 02527707, drug code 101675, sponsor Amylyx, prescription schedule, shows an original market date of 29 July 2022 and a current status of Cancelled Post Market with a history date of 23 September 2024. The product is no longer marketed in Canada.

Participants / model
Not a clinical population
Treatment
Oral sachet, fixed combination of sodium phenylbutyrate and ursodoxicoltaurine
Follow-up
Original market date 29 July 2022; cancelled 23 September 2024
Study design
Regulatory database record
Funding
not stated in the source

The record concerns the fixed combination, not TUDCA alone.

Read the original source

What did the liver trials of TUDCA find?

In 199 Chinese adults with primary biliary cholangitis, TUDCA was non-inferior to UDCA on alkaline phosphatase response over 24 weeks, and in 150 patients with HCV-related chronic hepatitis aminotransferases fell on TUDCA versus placebo over 6 months. Neither population is a steroid user, and neither trial measured protection from drug-induced liver injury.

The largest trial of TUDCA in liver disease was a multicenter randomized double-blind trial in 199 Chinese patients with primary biliary cholangitis. They received TUDCA plus a UDCA placebo, or UDCA plus a TUDCA placebo, for 24 weeks. At week 24, 75.97% on TUDCA and 80.88% on UDCA achieved an alkaline phosphatase reduction of more than 25% from baseline (P = 0.453), and 55.81% versus 52.94% achieved more than 40% (P = 0.699). ALP, AST and total bilirubin improved similarly in both arms. Pruritus or scratching rose from 1.43% to 10.00% in the UDCA group with no change in the TUDCA group (P = 0.023). The conclusion is non-inferiority to UDCA in cholestatic liver disease, not superiority, and not a result in healthy livers.

A multicenter placebo-controlled study randomized 150 patients with HCV-related chronic hepatitis to TUDCA at one of two daily dose levels or placebo for 6 months. Aminotransferase levels fell consistently on TUDCA compared with placebo (p < 0.001), with progressive improvement over time (p < 0.05, linear time effect). The authors state that long-term studies with clinically relevant endpoints are warranted. This is a biochemical endpoint in a viral hepatitis population, not a clinical outcome and not a protection result in drug-induced injury.

PBC trial: 199 Chinese adults, TUDCA non-inferior to UDCA over 24 weeks

Randomized controlled trial

Ma H et al. Medicine (Baltimore). 2016;95(47):e5391. PMID 27893675.

A multicenter randomized double-blind trial in 199 Chinese patients with primary biliary cholangitis gave TUDCA plus UDCA placebo or UDCA plus TUDCA placebo for 24 weeks. At week 24, 75.97% on TUDCA and 80.88% on UDCA achieved an alkaline phosphatase reduction of more than 25% from baseline (P = 0.453), and 55.81% versus 52.94% achieved more than 40% (P = 0.699). ALP, AST and total bilirubin improved similarly in both arms. Pruritus or scratching rose from 1.43% to 10.00% in the UDCA group with no change in the TUDCA group (P = 0.023).

Participants / model
199 adults with primary biliary cholangitis
Treatment
Oral TUDCA versus oral UDCA, each with a matching placebo (doses not reproduced on this page)
Follow-up
24 weeks
Study design
Multicenter randomized double-blind active-controlled trial
Funding
not stated in the source

The conclusion is non-inferiority to UDCA in cholestatic liver disease, not superiority, and not a result in healthy livers. It is the largest trial of TUDCA in liver disease.

Read the original source
HCV hepatitis trial: 150 patients, aminotransferases fell over 6 months

Randomized controlled trial

Crosignani A et al. Hepatogastroenterology. 1998;45(23):1624-9. PMID 9840118.

A multicenter placebo-controlled study randomized 150 patients with HCV-related chronic hepatitis to TUDCA at one of two daily dose levels or placebo for 6 months. Aminotransferase levels fell consistently on TUDCA compared with placebo (p < 0.001), with progressive improvement over time (p < 0.05, linear time effect). The authors state that long-term studies with clinically relevant endpoints are warranted.

Participants / model
150 patients with HCV-related chronic hepatitis
Treatment
Oral TUDCA at two daily dose levels or placebo (doses not reproduced on this page)
Follow-up
6 months
Study design
Multicenter randomized placebo-controlled trial
Funding
not stated in the source

This is a biochemical endpoint in a viral hepatitis population, not a clinical outcome and not a protection result in drug-induced injury.

Read the original source

What did the ALS trials find?

The approved combination slowed ALSFRS-R decline by 0.42 points per month in CENTAUR (137 adults, 24 weeks), but the phase 3 PHOENIX trial missed its endpoints and a 2026 meta-analysis of 801 participants found no significant effect on function or survival at very low certainty. The one randomized trial of TUDCA alone in ALS is a 34-patient pilot.

CENTAUR, the trial behind the approval, randomized 137 people with definite ALS and symptom onset within 18 months, 2:1, to sodium phenylbutyrate-taurursodiol or placebo for 24 weeks. The mean rate of change in ALSFRS-R was -1.24 points per month on the active drug versus -1.66 on placebo (difference 0.42 points per month, 95% CI 0.03 to 0.81, P = 0.03). Secondary outcomes, including muscle strength, plasma phosphorylated neurofilament H, slow vital capacity, and time to death, tracheostomy, permanent ventilation or hospitalization, did not differ significantly. Adverse events were mainly gastrointestinal. The trial is registered as NCT03127514 and tested the fixed combination, not TUDCA alone.

The phase 3 PHOENIX trial did not meet its prespecified primary and secondary endpoints, as reported in FDA's withdrawal notice. A 2026 systematic review and meta-analysis of randomized trials of PB-TURSO in ALS pooled 2 trials with 801 participants and found no statistically significant difference in ALSFRS-R decline (mean difference 1.51, 95% CI -1.01 to 4.02, P = 0.24, I2 = 71%) or survival (hazard ratio 0.90, 95% CI 0.73 to 1.11, P = 0.31, I2 = 61%). Risk of bias was moderate to high and GRADE certainty was very low. The authors describe the post hoc CENTAUR survival analyses as hypothesis-generating rather than practice-defining.

The only randomized trial of TUDCA alone in ALS was a double-blind placebo-controlled proof of principle study in 34 patients already on riluzole, given TUDCA or placebo for 54 weeks after a 3-month lead-in. The proportion of responders, defined as at least a 15% improvement in ALSFRS-R slope versus the lead-in, was 87% on TUDCA versus 43% on placebo (P = 0.021), baseline-adjusted ALSFRS-R at study end was higher (P = 0.007), and the regression slopes showed slower progression (P < 0.01). The authors describe it as a pilot providing preliminary data.

The registry record for TUDCA-ALS (NCT03800524), a phase 3 multicenter randomized double-blind placebo-controlled trial of TUDCA as add-on treatment (enrollment 337, sponsor Humanitas Mirasole SpA, start 22 February 2019, primary completion and completion dates both listed as 31 December 2023), showed an overall status of Unknown on 9 October 2026, was last updated on 10 July 2023 and posts no results. A registered phase 3 trial without posted results cannot supply an efficacy, pharmacokinetic or safety result.

CENTAUR: 137 adults with ALS, 24 weeks, combination versus placebo

Randomized controlled trial

Paganoni S et al. N Engl J Med. 2020;383(10):919-930. PMID 32877582.

CENTAUR randomized 137 people with definite ALS and symptom onset within 18 months, 2:1, to sodium phenylbutyrate-taurursodiol or placebo for 24 weeks. The mean rate of change in ALSFRS-R was -1.24 points per month on the active drug versus -1.66 on placebo (difference 0.42 points per month, 95% CI 0.03 to 0.81, P = 0.03). Secondary outcomes, including muscle strength, plasma phosphorylated neurofilament H, slow vital capacity, and time to death, tracheostomy, permanent ventilation or hospitalization, did not differ significantly. Adverse events were mainly gastrointestinal.

Participants / model
137 adults with definite ALS
Treatment
Oral fixed combination of sodium phenylbutyrate and taurursodiol, or placebo
Follow-up
24 weeks
Study design
Randomized placebo-controlled trial (2:1)
Funding
not stated in the source

This is a trial of the fixed combination, not TUDCA alone. The trial behind the approval was followed by PHOENIX, which missed its endpoints.

Read the original source
Federal Register, 29 August 2025: approval of RELYVRIO withdrawn after PHOENIX missed its endpoints

Regulatory record

U.S. Food and Drug Administration. Amylyx Pharmaceuticals, Inc.; Withdrawal of Approval of New Drug Application for RELYVRIO (sodium phenylbutyrate and taurursodiol) for oral suspension. Federal Register, 29 August 2025, 90 FR 42251.

FDA withdrew approval of NDA 216660 as of 29 August 2025. The notice states that on 30 April 2024 Amylyx reported that the phase 3 PHOENIX trial (Study A35-004), a global 48-week randomized placebo-controlled trial, did not meet its prespecified primary and secondary endpoints; that Amylyx notified FDA on 30 September 2024 of plans to discontinue marketing as of 31 October 2024; that FDA then requested a voluntary withdrawal request under 21 CFR 314.150(d); and that Amylyx submitted that request on 28 February 2025 and waived a hearing. The notice adds that distributing the product in interstate commerce without an approved application is illegal.

Participants / model
Not a clinical population
Treatment
Oral suspension product
Follow-up
Events from 30 April 2024 to 29 August 2025
Study design
Federal Register notice of withdrawal
Funding
not stated in the source

The withdrawal concerns the fixed combination and the trial result behind it.

Read the original source
2026 meta-analysis: 2 trials, 801 participants, no significant effect

Systematic review and meta-analysis

Jomaa AM et al. Ann Indian Acad Neurol. 2026;29(3):343-352. PMID 42301686.

A 2026 systematic review and meta-analysis of randomized trials of PB-TURSO in ALS pooled 2 trials with 801 participants and found no statistically significant difference in ALSFRS-R decline (mean difference 1.51, 95% CI -1.01 to 4.02, P = 0.24, I2 = 71%) or survival (hazard ratio 0.90, 95% CI 0.73 to 1.11, P = 0.31, I2 = 61%). Risk of bias was moderate to high and GRADE certainty was very low. The authors describe the post hoc CENTAUR survival analyses as hypothesis-generating rather than practice-defining.

Participants / model
801 adults with ALS across 2 randomized trials
Treatment
Oral fixed combination of sodium phenylbutyrate and taurursodiol
Follow-up
Pooled trials
Study design
Systematic review and meta-analysis
Funding
not stated in the source

This is the fixed combination, not TUDCA alone.

Read the original source
TUDCA alone in ALS: 34 patients on riluzole, 54 weeks, pilot

Randomized controlled trial

Elia AE et al. Eur J Neurol. 2016;23(1):45-52. PMID 25664595.

A double-blind placebo-controlled proof of principle study in 34 patients already on riluzole, given TUDCA or placebo for 54 weeks after a 3-month lead-in. The proportion of responders, defined as at least a 15% improvement in ALSFRS-R slope versus the lead-in, was 87% on TUDCA versus 43% on placebo (P = 0.021), baseline-adjusted ALSFRS-R at study end was higher (P = 0.007), and the regression slopes showed slower progression (P < 0.01). TUDCA was well tolerated with no between-group difference in adverse events. The authors describe it as a pilot providing preliminary data.

Participants / model
34 adults with ALS on riluzole
Treatment
Oral TUDCA or placebo (dose not reproduced on this page)
Follow-up
54 weeks after a 3-month lead-in
Study design
Randomized double-blind placebo-controlled pilot
Funding
not stated in the source

The only randomized trial of TUDCA alone in ALS. It is a pilot in 34 patients, not a confirmatory trial.

Read the original source
TUDCA-ALS registry record: phase 3, 337 planned, status Unknown, no posted results

Trial registry record

ClinicalTrials.gov record NCT03800524 (TUDCA-ALS), sponsor Humanitas Mirasole SpA. Read on 9 October 2026.

NCT03800524 is the registry record for TUDCA-ALS, a phase 3 multicenter randomized double-blind placebo-controlled trial of TUDCA as add-on treatment, enrollment 337, sponsor Humanitas Mirasole SpA, start 22 February 2019, primary completion and completion dates both listed as 31 December 2023. As read on 9 October 2026 the overall status is Unknown, the last update was posted on 10 July 2023, and no results are posted. A registered phase 3 trial without posted results cannot supply an efficacy, pharmacokinetic or safety result.

Participants / model
Adults with ALS
Treatment
Oral TUDCA as add-on treatment
Follow-up
Start 22 February 2019; completion dates listed as 31 December 2023
Study design
Registry record; no posted results
Funding
not stated in the source

Registered endpoints are disease progression endpoints; no results are posted. The registry status has been Unknown since the last update on 10 July 2023.

Read the original source

Does TUDCA protect the liver during oral steroid use?

No study shows it. A PubMed title and abstract search on 9 October 2026 pairing TUDCA with anabolic androgenic steroid terms returned 3 records, none of TUDCA given with an anabolic steroid in any species. The one human report of TUDCA taken as liver protection is a 2026 case report in which drug-induced liver injury occurred anyway.

The claim being tested is that TUDCA protects the liver during use of hepatotoxic oral steroids and supports hepatocytes under general stress.

A PubMed title and abstract search run on 9 October 2026 pairing TUDCA, taurursodiol or tauroursodeoxycholate with anabolic, androgenic, methyltestosterone, stanozolol, oxandrolone, methasterone, bodybuilding, bodybuilder or AAS terms returned 3 records: a bovine postmortem muscle metabolomics study, a tacrolimus-induced diabetes study in rats, and a study of TUDCA for age-related muscle loss in 18-month-old C57BL/6 mice. No human study, and no animal study, of TUDCA given alongside an anabolic androgenic steroid exists in the records reviewed.

The one published report of TUDCA used as intended hepatoprotection in a person is a 2026 case report of fenbendazole-associated drug-induced liver injury in a patient who was concurrently taking tauroursodeoxycholic acid as an intended hepatoprotective agent. The authors describe it as the first published report of this exposure combination. A single case cannot establish benefit or harm, but it is the only human record located in which TUDCA was taken for the protective purpose the supplier describes, and liver injury occurred anyway.

The liver trials above are in patients with cholestatic and hepatitis disease, and none measured protection from drug-induced injury. No source reviewed tests general hepatocyte stress support or any human outcome for it.

PubMed search, 9 October 2026: 3 records, none of TUDCA given with an anabolic steroid

PubMed search record

PubMed title and abstract search run on 9 October 2026: (tauroursodeoxycholic[tiab] OR TUDCA[tiab] OR taurursodiol[tiab] OR tauroursodeoxycholate[tiab]) AND (anabolic[tiab] OR methyltestosterone[tiab] OR stanozolol[tiab] OR oxandrolone[tiab] OR methasterone[tiab] OR bodybuilding[tiab] OR bodybuilder*[tiab] OR androgenic[tiab] OR AAS[tiab]). 3 records returned.

A PubMed title and abstract search run on 9 October 2026 pairing TUDCA, taurursodiol or tauroursodeoxycholate with anabolic, androgenic, methyltestosterone, stanozolol, oxandrolone, methasterone, bodybuilding, bodybuilder or AAS returned 3 records: a bovine postmortem muscle metabolomics study, a tacrolimus-induced diabetes study in rats, and a study of TUDCA for age-related muscle loss in 18-month-old C57BL/6 mice. No human study, and no animal study, of TUDCA given alongside an anabolic androgenic steroid exists in the records reviewed.

Participants / model
Records reviewed, not a population
Treatment
Not applicable
Follow-up
Search run on 9 October 2026
Study design
Literature search
Funding
not stated in the source

A search result shows what PubMed returned on that date. It is not proof that no unindexed study exists.

Read the original source
2026 case report: liver injury despite TUDCA taken as hepatoprotection

Case report

Satinsky A et al. ACG Case Rep J. 2026;13(7):e02222. PMID 42383214.

A 2026 case report of fenbendazole-associated drug-induced liver injury in a patient who was concurrently taking tauroursodeoxycholic acid as an intended hepatoprotective agent. The authors describe it as the first published report of this exposure combination.

Participants / model
One adult patient
Treatment
Oral TUDCA alongside oral fenbendazole
Follow-up
not stated in the source
Study design
Case report
Funding
not stated in the source

A single case cannot establish benefit or harm. It is the only human record located in which TUDCA was taken for the protective purpose the supplier describes, and liver injury occurred anyway.

Read the original source
PBC trial: 199 Chinese adults, TUDCA non-inferior to UDCA over 24 weeks

Randomized controlled trial

Ma H et al. Medicine (Baltimore). 2016;95(47):e5391. PMID 27893675.

A multicenter randomized double-blind trial in 199 Chinese patients with primary biliary cholangitis gave TUDCA plus UDCA placebo or UDCA plus TUDCA placebo for 24 weeks. At week 24, 75.97% on TUDCA and 80.88% on UDCA achieved an alkaline phosphatase reduction of more than 25% from baseline (P = 0.453), and 55.81% versus 52.94% achieved more than 40% (P = 0.699). ALP, AST and total bilirubin improved similarly in both arms. Pruritus or scratching rose from 1.43% to 10.00% in the UDCA group with no change in the TUDCA group (P = 0.023).

Participants / model
199 adults with primary biliary cholangitis
Treatment
Oral TUDCA versus oral UDCA, each with a matching placebo (doses not reproduced on this page)
Follow-up
24 weeks
Study design
Multicenter randomized double-blind active-controlled trial
Funding
not stated in the source

The conclusion is non-inferiority to UDCA in cholestatic liver disease, not superiority, and not a result in healthy livers. It is the largest trial of TUDCA in liver disease.

Read the original source
HCV hepatitis trial: 150 patients, aminotransferases fell over 6 months

Randomized controlled trial

Crosignani A et al. Hepatogastroenterology. 1998;45(23):1624-9. PMID 9840118.

A multicenter placebo-controlled study randomized 150 patients with HCV-related chronic hepatitis to TUDCA at one of two daily dose levels or placebo for 6 months. Aminotransferase levels fell consistently on TUDCA compared with placebo (p < 0.001), with progressive improvement over time (p < 0.05, linear time effect). The authors state that long-term studies with clinically relevant endpoints are warranted.

Participants / model
150 patients with HCV-related chronic hepatitis
Treatment
Oral TUDCA at two daily dose levels or placebo (doses not reproduced on this page)
Follow-up
6 months
Study design
Multicenter randomized placebo-controlled trial
Funding
not stated in the source

This is a biochemical endpoint in a viral hepatitis population, not a clinical outcome and not a protection result in drug-induced injury.

Read the original source

How does TUDCA work, and what does the body do with it?

The RELYVRIO label states the mechanism in ALS is unknown. For taurursodiol after a single dose of the fixed combination in healthy subjects, median Tmax was 4.5 hours and plasma protein binding 98%, and the major metabolites were ursodiol and glyco-ursodiol; no human mass balance study has been conducted.

The 2022 RELYVRIO label is the only FDA label that describes taurursodiol in humans, and it states the mechanism in ALS as unknown. Every figure from it describes the fixed combination with sodium phenylbutyrate, not a single-ingredient TUDCA supplement.

For taurursodiol in healthy subjects after a single dose of the combination, median Tmax was 4.5 hours and plasma protein binding was 98%. A high-fat meal did not significantly affect Cmax but increased AUC by 39%. The major metabolites are ursodiol and glyco-ursodiol, and no human mass balance study has been conducted. The label figures reviewed give no half-life for taurursodiol.

RELYVRIO 2022 label: warnings, adverse reactions and taurursodiol pharmacokinetics (combination)

FDA prescribing information

U.S. Food and Drug Administration. RELYVRIO (sodium phenylbutyrate and taurursodiol) for oral suspension, prescribing information, original 2022 label for NDA 216660.

The 2022 RELYVRIO label is the only FDA label that describes taurursodiol in humans. Mechanism in ALS is stated as unknown. Warnings: patients with disorders that interfere with bile acid circulation may have an increased risk of worsening diarrhea, and pancreatic insufficiency, intestinal malabsorption or intestinal disease may reduce absorption; such patients were excluded from the trial, so there is no clinical experience in those conditions. A second warning covers the high salt content of the combination. Adverse reactions in Study 1 versus placebo: diarrhea 25 versus 19%, abdominal pain 21 versus 13%, nausea 18 versus 13%, upper respiratory tract infection 18 versus 10%, fatigue 12 versus 6%, salivary hypersecretion 11 versus 2%, dizziness 10 versus 4%. Pharmacokinetics for taurursodiol: median Tmax 4.5 hours, plasma protein binding 98%, a high-fat meal did not significantly affect Cmax but increased AUC by 39%, major metabolites ursodiol and glyco-ursodiol, and no human mass balance study has been conducted. Bile acid sequestering agents may interfere with absorption.

Participants / model
Adults with ALS; healthy subjects for the single-dose pharmacokinetics
Treatment
Oral suspension, fixed combination with sodium phenylbutyrate
Follow-up
Original 2022 label
Study design
FDA prescribing information
Funding
not stated in the source

All pharmacokinetic, salt and adverse reaction figures belong to the fixed combination, not to a single-ingredient TUDCA supplement. The salt warning comes with the sodium phenylbutyrate component, not with taurursodiol.

Read the original source
PubChem: TUDCA identity, synonyms and dihydrate used in the approved product

Chemical identity record

National Library of Medicine. PubChem compound record CID 9848818 (tauroursodeoxycholic acid).

Tauroursodeoxycholic acid: PubChem CID 9848818, C26H45NO6S, molecular weight 499.7 g/mol, CAS 14605-22-2. Listed synonyms include TUDCA, taurursodiol, ursodoxicoltaurine, ursodeoxycholyltaurine and UR-906. It is the taurine conjugate of ursodeoxycholic acid, which is a separate approved drug and a separate molecule. The FDA-approved product used the dihydrate, C26H45NO6S.2H2O, molecular weight 535.74, so figures taken from that label are dihydrate figures.

Participants / model
Chemical identity, not a clinical population
Treatment
Defined bile acid and its dihydrate
Follow-up
Not applicable
Study design
NLM chemical record
Funding
not stated in the source

Identity record only; it says nothing about efficacy or safety.

Read the original source

What risks do the label and trials report?

The RELYVRIO label warns that patients with disorders that interfere with bile acid circulation may have worsening diarrhea, and in its ALS trial diarrhea, abdominal pain and nausea were more common than on placebo. Those figures belong to the fixed combination, not to single-ingredient TUDCA.

The RELYVRIO label warns that patients with disorders that interfere with bile acid circulation may have an increased risk of worsening diarrhea, and that pancreatic insufficiency, intestinal malabsorption or intestinal disease may reduce absorption. Such patients were excluded from the trial, so there is no clinical experience in those conditions. A second warning covers the high salt content of the combination, which comes with the sodium phenylbutyrate component and is not a property of TUDCA.

In Study 1 versus placebo, adverse reactions included diarrhea (25% versus 19%), abdominal pain (21% versus 13%), nausea (18% versus 13%), upper respiratory tract infection (18% versus 10%), fatigue (12% versus 6%), salivary hypersecretion (11% versus 2%) and dizziness (10% versus 4%). These are figures for the fixed combination. The label says bile acid sequestering agents may interfere with absorption.

In the 34-patient ALS pilot, TUDCA alone was well tolerated with no between-group difference in adverse events. In the primary biliary cholangitis trial, pruritus or scratching rose from 1.43% to 10.00% in the UDCA group with no change in the TUDCA group (P = 0.023).

In the 2026 case report, drug-induced liver injury occurred in a patient taking TUDCA as an intended hepatoprotective agent alongside fenbendazole. A single case cannot show benefit or harm.

RELYVRIO 2022 label: warnings, adverse reactions and taurursodiol pharmacokinetics (combination)

FDA prescribing information

U.S. Food and Drug Administration. RELYVRIO (sodium phenylbutyrate and taurursodiol) for oral suspension, prescribing information, original 2022 label for NDA 216660.

The 2022 RELYVRIO label is the only FDA label that describes taurursodiol in humans. Mechanism in ALS is stated as unknown. Warnings: patients with disorders that interfere with bile acid circulation may have an increased risk of worsening diarrhea, and pancreatic insufficiency, intestinal malabsorption or intestinal disease may reduce absorption; such patients were excluded from the trial, so there is no clinical experience in those conditions. A second warning covers the high salt content of the combination. Adverse reactions in Study 1 versus placebo: diarrhea 25 versus 19%, abdominal pain 21 versus 13%, nausea 18 versus 13%, upper respiratory tract infection 18 versus 10%, fatigue 12 versus 6%, salivary hypersecretion 11 versus 2%, dizziness 10 versus 4%. Pharmacokinetics for taurursodiol: median Tmax 4.5 hours, plasma protein binding 98%, a high-fat meal did not significantly affect Cmax but increased AUC by 39%, major metabolites ursodiol and glyco-ursodiol, and no human mass balance study has been conducted. Bile acid sequestering agents may interfere with absorption.

Participants / model
Adults with ALS; healthy subjects for the single-dose pharmacokinetics
Treatment
Oral suspension, fixed combination with sodium phenylbutyrate
Follow-up
Original 2022 label
Study design
FDA prescribing information
Funding
not stated in the source

All pharmacokinetic, salt and adverse reaction figures belong to the fixed combination, not to a single-ingredient TUDCA supplement. The salt warning comes with the sodium phenylbutyrate component, not with taurursodiol.

Read the original source
TUDCA alone in ALS: 34 patients on riluzole, 54 weeks, pilot

Randomized controlled trial

Elia AE et al. Eur J Neurol. 2016;23(1):45-52. PMID 25664595.

A double-blind placebo-controlled proof of principle study in 34 patients already on riluzole, given TUDCA or placebo for 54 weeks after a 3-month lead-in. The proportion of responders, defined as at least a 15% improvement in ALSFRS-R slope versus the lead-in, was 87% on TUDCA versus 43% on placebo (P = 0.021), baseline-adjusted ALSFRS-R at study end was higher (P = 0.007), and the regression slopes showed slower progression (P < 0.01). TUDCA was well tolerated with no between-group difference in adverse events. The authors describe it as a pilot providing preliminary data.

Participants / model
34 adults with ALS on riluzole
Treatment
Oral TUDCA or placebo (dose not reproduced on this page)
Follow-up
54 weeks after a 3-month lead-in
Study design
Randomized double-blind placebo-controlled pilot
Funding
not stated in the source

The only randomized trial of TUDCA alone in ALS. It is a pilot in 34 patients, not a confirmatory trial.

Read the original source
PBC trial: 199 Chinese adults, TUDCA non-inferior to UDCA over 24 weeks

Randomized controlled trial

Ma H et al. Medicine (Baltimore). 2016;95(47):e5391. PMID 27893675.

A multicenter randomized double-blind trial in 199 Chinese patients with primary biliary cholangitis gave TUDCA plus UDCA placebo or UDCA plus TUDCA placebo for 24 weeks. At week 24, 75.97% on TUDCA and 80.88% on UDCA achieved an alkaline phosphatase reduction of more than 25% from baseline (P = 0.453), and 55.81% versus 52.94% achieved more than 40% (P = 0.699). ALP, AST and total bilirubin improved similarly in both arms. Pruritus or scratching rose from 1.43% to 10.00% in the UDCA group with no change in the TUDCA group (P = 0.023).

Participants / model
199 adults with primary biliary cholangitis
Treatment
Oral TUDCA versus oral UDCA, each with a matching placebo (doses not reproduced on this page)
Follow-up
24 weeks
Study design
Multicenter randomized double-blind active-controlled trial
Funding
not stated in the source

The conclusion is non-inferiority to UDCA in cholestatic liver disease, not superiority, and not a result in healthy livers. It is the largest trial of TUDCA in liver disease.

Read the original source
2026 case report: liver injury despite TUDCA taken as hepatoprotection

Case report

Satinsky A et al. ACG Case Rep J. 2026;13(7):e02222. PMID 42383214.

A 2026 case report of fenbendazole-associated drug-induced liver injury in a patient who was concurrently taking tauroursodeoxycholic acid as an intended hepatoprotective agent. The authors describe it as the first published report of this exposure combination.

Participants / model
One adult patient
Treatment
Oral TUDCA alongside oral fenbendazole
Follow-up
not stated in the source
Study design
Case report
Funding
not stated in the source

A single case cannot establish benefit or harm. It is the only human record located in which TUDCA was taken for the protective purpose the supplier describes, and liver injury occurred anyway.

Read the original source

Why does TUDCA sit in C tier?

TUDCA's one FDA approval, as half of a fixed combination for ALS, was withdrawn after a phase 3 trial missed its endpoints, but randomized trials in primary biliary cholangitis and HCV hepatitis give real, narrow human liver data. The grade does not cover the supplier's steroid-liver-protection claim, which no study tests.

TUDCA has had one FDA approval, and it is gone: NDA 216660 was approved on 29 September 2022 as half of a fixed combination, the phase 3 PHOENIX trial missed its primary and secondary endpoints, and approval was withdrawn as of 29 August 2025. EMA refused the same combination, confirmed on re-examination, and Canada's listing is cancelled post market. The pooled randomized evidence in ALS across 801 participants shows no significant effect on function or survival, at very low certainty.

What survives is a genuine but narrow body of work in cholestatic and hepatitis populations: non-inferiority to UDCA on alkaline phosphatase response in 199 patients with primary biliary cholangitis, and an aminotransferase reduction in 150 patients with HCV-related hepatitis. That is real human liver data, which is why the grade is C.

The supplier claim fails on population and on evidence: no study in any species pairs TUDCA with an anabolic androgenic steroid, and the only human record of TUDCA taken as hepatoprotection is a case report in which drug-induced liver injury happened regardless.

Drugs@FDA: RELYVRIO approved 29 September 2022, marketing status Discontinued

Regulatory record

U.S. Food and Drug Administration. Drugs@FDA application record for NDA 216660 (RELYVRIO, sodium phenylbutyrate and taurursodiol), with the openFDA record and a DailyMed drug name search for tauroursodeoxycholic read on 9 October 2026.

FDA approved NDA 216660 for RELYVRIO, a fixed combination of sodium phenylbutyrate and taurursodiol as an oral suspension, on 29 September 2022, as a priority review, type 1 new molecular entity, with orphan designation, sponsor Amylyx. The openFDA record read on 9 October 2026 lists the product marketing status as Discontinued. Taurursodiol has never been approved in the US as a single ingredient, and a DailyMed drug name search for tauroursodeoxycholic on 9 October 2026 returned no labels.

Participants / model
Adults with ALS
Treatment
Oral suspension, fixed combination with sodium phenylbutyrate
Follow-up
Approval of 29 September 2022; status read on 9 October 2026
Study design
FDA application record
Funding
not stated in the source

The approval was for the fixed combination, not for TUDCA alone.

Read the original source
Federal Register, 29 August 2025: approval of RELYVRIO withdrawn after PHOENIX missed its endpoints

Regulatory record

U.S. Food and Drug Administration. Amylyx Pharmaceuticals, Inc.; Withdrawal of Approval of New Drug Application for RELYVRIO (sodium phenylbutyrate and taurursodiol) for oral suspension. Federal Register, 29 August 2025, 90 FR 42251.

FDA withdrew approval of NDA 216660 as of 29 August 2025. The notice states that on 30 April 2024 Amylyx reported that the phase 3 PHOENIX trial (Study A35-004), a global 48-week randomized placebo-controlled trial, did not meet its prespecified primary and secondary endpoints; that Amylyx notified FDA on 30 September 2024 of plans to discontinue marketing as of 31 October 2024; that FDA then requested a voluntary withdrawal request under 21 CFR 314.150(d); and that Amylyx submitted that request on 28 February 2025 and waived a hearing. The notice adds that distributing the product in interstate commerce without an approved application is illegal.

Participants / model
Not a clinical population
Treatment
Oral suspension product
Follow-up
Events from 30 April 2024 to 29 August 2025
Study design
Federal Register notice of withdrawal
Funding
not stated in the source

The withdrawal concerns the fixed combination and the trial result behind it.

Read the original source
EMA: Albrioza refused, opinion 22 June 2023, confirmed 12 October 2023, refusal 5 January 2024

Regulatory record

European Medicines Agency. Albrioza (sodium phenylbutyrate and ursodoxicoltaurine), European public assessment report and refusal record.

EMA refused marketing authorization for Albrioza (sodium phenylbutyrate and ursodoxicoltaurine) for ALS. The initial opinion was issued on 22 June 2023 and confirmed after re-examination on 12 October 2023, with refusal recorded on 5 January 2024. EMA states the main study in 137 patients did not convincingly show the medicine slowed worsening of the disease, that survival data were not reliable given how they were collected and analyzed, and that a positive benefit-risk balance could not be established.

Participants / model
Adults with ALS
Treatment
Oral powder for suspension, fixed combination
Follow-up
Opinion 22 June 2023; refusal recorded 5 January 2024
Study design
EMA benefit-risk assessment
Funding
not stated in the source

The refusal concerns the fixed combination, not TUDCA alone.

Read the original source
Health Canada: ALBRIOZA Cancelled Post Market, history date 23 September 2024

Regulatory record

Health Canada. Drug Product Database record for ALBRIOZA, DIN 02527707, drug code 101675, sponsor Amylyx.

Health Canada's Drug Product Database record for ALBRIOZA, DIN 02527707, drug code 101675, sponsor Amylyx, prescription schedule, shows an original market date of 29 July 2022 and a current status of Cancelled Post Market with a history date of 23 September 2024. The product is no longer marketed in Canada.

Participants / model
Not a clinical population
Treatment
Oral sachet, fixed combination of sodium phenylbutyrate and ursodoxicoltaurine
Follow-up
Original market date 29 July 2022; cancelled 23 September 2024
Study design
Regulatory database record
Funding
not stated in the source

The record concerns the fixed combination, not TUDCA alone.

Read the original source
PBC trial: 199 Chinese adults, TUDCA non-inferior to UDCA over 24 weeks

Randomized controlled trial

Ma H et al. Medicine (Baltimore). 2016;95(47):e5391. PMID 27893675.

A multicenter randomized double-blind trial in 199 Chinese patients with primary biliary cholangitis gave TUDCA plus UDCA placebo or UDCA plus TUDCA placebo for 24 weeks. At week 24, 75.97% on TUDCA and 80.88% on UDCA achieved an alkaline phosphatase reduction of more than 25% from baseline (P = 0.453), and 55.81% versus 52.94% achieved more than 40% (P = 0.699). ALP, AST and total bilirubin improved similarly in both arms. Pruritus or scratching rose from 1.43% to 10.00% in the UDCA group with no change in the TUDCA group (P = 0.023).

Participants / model
199 adults with primary biliary cholangitis
Treatment
Oral TUDCA versus oral UDCA, each with a matching placebo (doses not reproduced on this page)
Follow-up
24 weeks
Study design
Multicenter randomized double-blind active-controlled trial
Funding
not stated in the source

The conclusion is non-inferiority to UDCA in cholestatic liver disease, not superiority, and not a result in healthy livers. It is the largest trial of TUDCA in liver disease.

Read the original source
HCV hepatitis trial: 150 patients, aminotransferases fell over 6 months

Randomized controlled trial

Crosignani A et al. Hepatogastroenterology. 1998;45(23):1624-9. PMID 9840118.

A multicenter placebo-controlled study randomized 150 patients with HCV-related chronic hepatitis to TUDCA at one of two daily dose levels or placebo for 6 months. Aminotransferase levels fell consistently on TUDCA compared with placebo (p < 0.001), with progressive improvement over time (p < 0.05, linear time effect). The authors state that long-term studies with clinically relevant endpoints are warranted.

Participants / model
150 patients with HCV-related chronic hepatitis
Treatment
Oral TUDCA at two daily dose levels or placebo (doses not reproduced on this page)
Follow-up
6 months
Study design
Multicenter randomized placebo-controlled trial
Funding
not stated in the source

This is a biochemical endpoint in a viral hepatitis population, not a clinical outcome and not a protection result in drug-induced injury.

Read the original source
PubMed search, 9 October 2026: 3 records, none of TUDCA given with an anabolic steroid

PubMed search record

PubMed title and abstract search run on 9 October 2026: (tauroursodeoxycholic[tiab] OR TUDCA[tiab] OR taurursodiol[tiab] OR tauroursodeoxycholate[tiab]) AND (anabolic[tiab] OR methyltestosterone[tiab] OR stanozolol[tiab] OR oxandrolone[tiab] OR methasterone[tiab] OR bodybuilding[tiab] OR bodybuilder*[tiab] OR androgenic[tiab] OR AAS[tiab]). 3 records returned.

A PubMed title and abstract search run on 9 October 2026 pairing TUDCA, taurursodiol or tauroursodeoxycholate with anabolic, androgenic, methyltestosterone, stanozolol, oxandrolone, methasterone, bodybuilding, bodybuilder or AAS returned 3 records: a bovine postmortem muscle metabolomics study, a tacrolimus-induced diabetes study in rats, and a study of TUDCA for age-related muscle loss in 18-month-old C57BL/6 mice. No human study, and no animal study, of TUDCA given alongside an anabolic androgenic steroid exists in the records reviewed.

Participants / model
Records reviewed, not a population
Treatment
Not applicable
Follow-up
Search run on 9 October 2026
Study design
Literature search
Funding
not stated in the source

A search result shows what PubMed returned on that date. It is not proof that no unindexed study exists.

Read the original source
2026 case report: liver injury despite TUDCA taken as hepatoprotection

Case report

Satinsky A et al. ACG Case Rep J. 2026;13(7):e02222. PMID 42383214.

A 2026 case report of fenbendazole-associated drug-induced liver injury in a patient who was concurrently taking tauroursodeoxycholic acid as an intended hepatoprotective agent. The authors describe it as the first published report of this exposure combination.

Participants / model
One adult patient
Treatment
Oral TUDCA alongside oral fenbendazole
Follow-up
not stated in the source
Study design
Case report
Funding
not stated in the source

A single case cannot establish benefit or harm. It is the only human record located in which TUDCA was taken for the protective purpose the supplier describes, and liver injury occurred anyway.

Read the original source

Studies and sources

PubChem: TUDCA identity, synonyms and dihydrate used in the approved product

Chemical identity record

National Library of Medicine. PubChem compound record CID 9848818 (tauroursodeoxycholic acid).

Tauroursodeoxycholic acid: PubChem CID 9848818, C26H45NO6S, molecular weight 499.7 g/mol, CAS 14605-22-2. Listed synonyms include TUDCA, taurursodiol, ursodoxicoltaurine, ursodeoxycholyltaurine and UR-906. It is the taurine conjugate of ursodeoxycholic acid, which is a separate approved drug and a separate molecule. The FDA-approved product used the dihydrate, C26H45NO6S.2H2O, molecular weight 535.74, so figures taken from that label are dihydrate figures.

Participants / model
Chemical identity, not a clinical population
Treatment
Defined bile acid and its dihydrate
Follow-up
Not applicable
Study design
NLM chemical record
Funding
not stated in the source

Identity record only; it says nothing about efficacy or safety.

Read the original source
Drugs@FDA: RELYVRIO approved 29 September 2022, marketing status Discontinued

Regulatory record

U.S. Food and Drug Administration. Drugs@FDA application record for NDA 216660 (RELYVRIO, sodium phenylbutyrate and taurursodiol), with the openFDA record and a DailyMed drug name search for tauroursodeoxycholic read on 9 October 2026.

FDA approved NDA 216660 for RELYVRIO, a fixed combination of sodium phenylbutyrate and taurursodiol as an oral suspension, on 29 September 2022, as a priority review, type 1 new molecular entity, with orphan designation, sponsor Amylyx. The openFDA record read on 9 October 2026 lists the product marketing status as Discontinued. Taurursodiol has never been approved in the US as a single ingredient, and a DailyMed drug name search for tauroursodeoxycholic on 9 October 2026 returned no labels.

Participants / model
Adults with ALS
Treatment
Oral suspension, fixed combination with sodium phenylbutyrate
Follow-up
Approval of 29 September 2022; status read on 9 October 2026
Study design
FDA application record
Funding
not stated in the source

The approval was for the fixed combination, not for TUDCA alone.

Read the original source
Federal Register, 29 August 2025: approval of RELYVRIO withdrawn after PHOENIX missed its endpoints

Regulatory record

U.S. Food and Drug Administration. Amylyx Pharmaceuticals, Inc.; Withdrawal of Approval of New Drug Application for RELYVRIO (sodium phenylbutyrate and taurursodiol) for oral suspension. Federal Register, 29 August 2025, 90 FR 42251.

FDA withdrew approval of NDA 216660 as of 29 August 2025. The notice states that on 30 April 2024 Amylyx reported that the phase 3 PHOENIX trial (Study A35-004), a global 48-week randomized placebo-controlled trial, did not meet its prespecified primary and secondary endpoints; that Amylyx notified FDA on 30 September 2024 of plans to discontinue marketing as of 31 October 2024; that FDA then requested a voluntary withdrawal request under 21 CFR 314.150(d); and that Amylyx submitted that request on 28 February 2025 and waived a hearing. The notice adds that distributing the product in interstate commerce without an approved application is illegal.

Participants / model
Not a clinical population
Treatment
Oral suspension product
Follow-up
Events from 30 April 2024 to 29 August 2025
Study design
Federal Register notice of withdrawal
Funding
not stated in the source

The withdrawal concerns the fixed combination and the trial result behind it.

Read the original source
RELYVRIO 2022 label: warnings, adverse reactions and taurursodiol pharmacokinetics (combination)

FDA prescribing information

U.S. Food and Drug Administration. RELYVRIO (sodium phenylbutyrate and taurursodiol) for oral suspension, prescribing information, original 2022 label for NDA 216660.

The 2022 RELYVRIO label is the only FDA label that describes taurursodiol in humans. Mechanism in ALS is stated as unknown. Warnings: patients with disorders that interfere with bile acid circulation may have an increased risk of worsening diarrhea, and pancreatic insufficiency, intestinal malabsorption or intestinal disease may reduce absorption; such patients were excluded from the trial, so there is no clinical experience in those conditions. A second warning covers the high salt content of the combination. Adverse reactions in Study 1 versus placebo: diarrhea 25 versus 19%, abdominal pain 21 versus 13%, nausea 18 versus 13%, upper respiratory tract infection 18 versus 10%, fatigue 12 versus 6%, salivary hypersecretion 11 versus 2%, dizziness 10 versus 4%. Pharmacokinetics for taurursodiol: median Tmax 4.5 hours, plasma protein binding 98%, a high-fat meal did not significantly affect Cmax but increased AUC by 39%, major metabolites ursodiol and glyco-ursodiol, and no human mass balance study has been conducted. Bile acid sequestering agents may interfere with absorption.

Participants / model
Adults with ALS; healthy subjects for the single-dose pharmacokinetics
Treatment
Oral suspension, fixed combination with sodium phenylbutyrate
Follow-up
Original 2022 label
Study design
FDA prescribing information
Funding
not stated in the source

All pharmacokinetic, salt and adverse reaction figures belong to the fixed combination, not to a single-ingredient TUDCA supplement. The salt warning comes with the sodium phenylbutyrate component, not with taurursodiol.

Read the original source
CENTAUR: 137 adults with ALS, 24 weeks, combination versus placebo

Randomized controlled trial

Paganoni S et al. N Engl J Med. 2020;383(10):919-930. PMID 32877582.

CENTAUR randomized 137 people with definite ALS and symptom onset within 18 months, 2:1, to sodium phenylbutyrate-taurursodiol or placebo for 24 weeks. The mean rate of change in ALSFRS-R was -1.24 points per month on the active drug versus -1.66 on placebo (difference 0.42 points per month, 95% CI 0.03 to 0.81, P = 0.03). Secondary outcomes, including muscle strength, plasma phosphorylated neurofilament H, slow vital capacity, and time to death, tracheostomy, permanent ventilation or hospitalization, did not differ significantly. Adverse events were mainly gastrointestinal.

Participants / model
137 adults with definite ALS
Treatment
Oral fixed combination of sodium phenylbutyrate and taurursodiol, or placebo
Follow-up
24 weeks
Study design
Randomized placebo-controlled trial (2:1)
Funding
not stated in the source

This is a trial of the fixed combination, not TUDCA alone. The trial behind the approval was followed by PHOENIX, which missed its endpoints.

Read the original source
2026 meta-analysis: 2 trials, 801 participants, no significant effect

Systematic review and meta-analysis

Jomaa AM et al. Ann Indian Acad Neurol. 2026;29(3):343-352. PMID 42301686.

A 2026 systematic review and meta-analysis of randomized trials of PB-TURSO in ALS pooled 2 trials with 801 participants and found no statistically significant difference in ALSFRS-R decline (mean difference 1.51, 95% CI -1.01 to 4.02, P = 0.24, I2 = 71%) or survival (hazard ratio 0.90, 95% CI 0.73 to 1.11, P = 0.31, I2 = 61%). Risk of bias was moderate to high and GRADE certainty was very low. The authors describe the post hoc CENTAUR survival analyses as hypothesis-generating rather than practice-defining.

Participants / model
801 adults with ALS across 2 randomized trials
Treatment
Oral fixed combination of sodium phenylbutyrate and taurursodiol
Follow-up
Pooled trials
Study design
Systematic review and meta-analysis
Funding
not stated in the source

This is the fixed combination, not TUDCA alone.

Read the original source
TUDCA alone in ALS: 34 patients on riluzole, 54 weeks, pilot

Randomized controlled trial

Elia AE et al. Eur J Neurol. 2016;23(1):45-52. PMID 25664595.

A double-blind placebo-controlled proof of principle study in 34 patients already on riluzole, given TUDCA or placebo for 54 weeks after a 3-month lead-in. The proportion of responders, defined as at least a 15% improvement in ALSFRS-R slope versus the lead-in, was 87% on TUDCA versus 43% on placebo (P = 0.021), baseline-adjusted ALSFRS-R at study end was higher (P = 0.007), and the regression slopes showed slower progression (P < 0.01). TUDCA was well tolerated with no between-group difference in adverse events. The authors describe it as a pilot providing preliminary data.

Participants / model
34 adults with ALS on riluzole
Treatment
Oral TUDCA or placebo (dose not reproduced on this page)
Follow-up
54 weeks after a 3-month lead-in
Study design
Randomized double-blind placebo-controlled pilot
Funding
not stated in the source

The only randomized trial of TUDCA alone in ALS. It is a pilot in 34 patients, not a confirmatory trial.

Read the original source
TUDCA-ALS registry record: phase 3, 337 planned, status Unknown, no posted results

Trial registry record

ClinicalTrials.gov record NCT03800524 (TUDCA-ALS), sponsor Humanitas Mirasole SpA. Read on 9 October 2026.

NCT03800524 is the registry record for TUDCA-ALS, a phase 3 multicenter randomized double-blind placebo-controlled trial of TUDCA as add-on treatment, enrollment 337, sponsor Humanitas Mirasole SpA, start 22 February 2019, primary completion and completion dates both listed as 31 December 2023. As read on 9 October 2026 the overall status is Unknown, the last update was posted on 10 July 2023, and no results are posted. A registered phase 3 trial without posted results cannot supply an efficacy, pharmacokinetic or safety result.

Participants / model
Adults with ALS
Treatment
Oral TUDCA as add-on treatment
Follow-up
Start 22 February 2019; completion dates listed as 31 December 2023
Study design
Registry record; no posted results
Funding
not stated in the source

Registered endpoints are disease progression endpoints; no results are posted. The registry status has been Unknown since the last update on 10 July 2023.

Read the original source
EMA: Albrioza refused, opinion 22 June 2023, confirmed 12 October 2023, refusal 5 January 2024

Regulatory record

European Medicines Agency. Albrioza (sodium phenylbutyrate and ursodoxicoltaurine), European public assessment report and refusal record.

EMA refused marketing authorization for Albrioza (sodium phenylbutyrate and ursodoxicoltaurine) for ALS. The initial opinion was issued on 22 June 2023 and confirmed after re-examination on 12 October 2023, with refusal recorded on 5 January 2024. EMA states the main study in 137 patients did not convincingly show the medicine slowed worsening of the disease, that survival data were not reliable given how they were collected and analyzed, and that a positive benefit-risk balance could not be established.

Participants / model
Adults with ALS
Treatment
Oral powder for suspension, fixed combination
Follow-up
Opinion 22 June 2023; refusal recorded 5 January 2024
Study design
EMA benefit-risk assessment
Funding
not stated in the source

The refusal concerns the fixed combination, not TUDCA alone.

Read the original source
Health Canada: ALBRIOZA Cancelled Post Market, history date 23 September 2024

Regulatory record

Health Canada. Drug Product Database record for ALBRIOZA, DIN 02527707, drug code 101675, sponsor Amylyx.

Health Canada's Drug Product Database record for ALBRIOZA, DIN 02527707, drug code 101675, sponsor Amylyx, prescription schedule, shows an original market date of 29 July 2022 and a current status of Cancelled Post Market with a history date of 23 September 2024. The product is no longer marketed in Canada.

Participants / model
Not a clinical population
Treatment
Oral sachet, fixed combination of sodium phenylbutyrate and ursodoxicoltaurine
Follow-up
Original market date 29 July 2022; cancelled 23 September 2024
Study design
Regulatory database record
Funding
not stated in the source

The record concerns the fixed combination, not TUDCA alone.

Read the original source
PBC trial: 199 Chinese adults, TUDCA non-inferior to UDCA over 24 weeks

Randomized controlled trial

Ma H et al. Medicine (Baltimore). 2016;95(47):e5391. PMID 27893675.

A multicenter randomized double-blind trial in 199 Chinese patients with primary biliary cholangitis gave TUDCA plus UDCA placebo or UDCA plus TUDCA placebo for 24 weeks. At week 24, 75.97% on TUDCA and 80.88% on UDCA achieved an alkaline phosphatase reduction of more than 25% from baseline (P = 0.453), and 55.81% versus 52.94% achieved more than 40% (P = 0.699). ALP, AST and total bilirubin improved similarly in both arms. Pruritus or scratching rose from 1.43% to 10.00% in the UDCA group with no change in the TUDCA group (P = 0.023).

Participants / model
199 adults with primary biliary cholangitis
Treatment
Oral TUDCA versus oral UDCA, each with a matching placebo (doses not reproduced on this page)
Follow-up
24 weeks
Study design
Multicenter randomized double-blind active-controlled trial
Funding
not stated in the source

The conclusion is non-inferiority to UDCA in cholestatic liver disease, not superiority, and not a result in healthy livers. It is the largest trial of TUDCA in liver disease.

Read the original source
HCV hepatitis trial: 150 patients, aminotransferases fell over 6 months

Randomized controlled trial

Crosignani A et al. Hepatogastroenterology. 1998;45(23):1624-9. PMID 9840118.

A multicenter placebo-controlled study randomized 150 patients with HCV-related chronic hepatitis to TUDCA at one of two daily dose levels or placebo for 6 months. Aminotransferase levels fell consistently on TUDCA compared with placebo (p < 0.001), with progressive improvement over time (p < 0.05, linear time effect). The authors state that long-term studies with clinically relevant endpoints are warranted.

Participants / model
150 patients with HCV-related chronic hepatitis
Treatment
Oral TUDCA at two daily dose levels or placebo (doses not reproduced on this page)
Follow-up
6 months
Study design
Multicenter randomized placebo-controlled trial
Funding
not stated in the source

This is a biochemical endpoint in a viral hepatitis population, not a clinical outcome and not a protection result in drug-induced injury.

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2026 case report: liver injury despite TUDCA taken as hepatoprotection

Case report

Satinsky A et al. ACG Case Rep J. 2026;13(7):e02222. PMID 42383214.

A 2026 case report of fenbendazole-associated drug-induced liver injury in a patient who was concurrently taking tauroursodeoxycholic acid as an intended hepatoprotective agent. The authors describe it as the first published report of this exposure combination.

Participants / model
One adult patient
Treatment
Oral TUDCA alongside oral fenbendazole
Follow-up
not stated in the source
Study design
Case report
Funding
not stated in the source

A single case cannot establish benefit or harm. It is the only human record located in which TUDCA was taken for the protective purpose the supplier describes, and liver injury occurred anyway.

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Why is TUDCA (tauroursodeoxycholic acid) in C tier?

C fits a compound with real but narrow human liver data and a withdrawn approval. The trials in primary biliary cholangitis and HCV hepatitis are real, and the ALS approval did not survive a phase 3 trial that missed its endpoints. The grade does not cover the supplier's claim of protecting the liver during oral steroid use, which no study tests.