Thozalinone

updated

Thozalinone (CL-39808) is an older stimulant, the N,N-dimethyl analog of pemoline, sold for wakefulness and motivation. Its record holds 1960s rodent papers, two human trial records in depression and obesity, two mouse studies that used it as a dopamine tool, and a product name, but every human record lacks an abstract and nothing measures wakefulness or motivation. Pemoline carried a documented liver-injury signal, and thozalinone's own safety is unstudied in the retrievable record.

Oxazolone stimulant, N,N-dimethyl analog of pemoline

  • PubChem lists thozalinone (CL-39808) as 2-(dimethylamino)-5-phenyl-1,3-oxazol-4-one, C11H12N2O2, molecular weight 204.22, the N,N-dimethyl analog of pemoline.
  • PubMed returned 7 records for thozalinone on 10 October 2026, and 4 of the 7, including both human trial records, have no abstract.
  • The human trial records are a 1966 double-blind study in depressed outpatients and a 1971 trial in obese patients; neither gives a result, dose, sample size or adverse event.
  • Two mouse studies, from 1980 and 1985, used thozalinone at 50 and 100 mg/kg intraperitoneally to provoke gnawing, a dopamine-linked readout and not a measure of wakefulness or motivation.
  • Pemoline, its close relative, drew 12 cases of jaundice and 6 deaths in youths reported to FDA from 1975 to 1989; whether thozalinone shares that signal is untested.
  • No retrievable record measures wakefulness, vigilance, alertness, motivation or sleep deprivation with thozalinone in any species.

What is thozalinone, and what is its regulatory status?

Thozalinone (CL-39808) is PubChem CID 12602, the N,N-dimethyl analog of pemoline. No US label, scheduling or enforcement record names it, and the WADA 2026 list names pemoline but not thozalinone. A product named Stimsen existed, but its status in any country is not shown.

Thozalinone is PubChem CID 12602, C11H12N2O2, molecular weight 204.22, IUPAC name 2-(dimethylamino)-5-phenyl-1,3-oxazol-4-one, with CAS 655-05-0 listed as a CAS-format synonym. Synonyms include Tozalinone, CL 39808, CL-39808 and NSC-170962. The title of the 1966 trial writes the code as C1 39,808, a typographic variant of CL 39,808. It is the N,N-dimethyl analog of pemoline (PubChem CID 4723, 2-amino-5-phenyl-1,3-oxazol-4-one, C9H8N2O2, molecular weight 176.17).

On 10 October 2026 openFDA Drugs@FDA queries by substance, generic and brand name for thozalinone returned no match, DailyMed returned 0 labels, and FDA's Health Fraud Product Database (2,213 entries, current as of 5 October 2026) has no entry naming it. 21 CFR Part 1308 (eCFR version of 6 October 2026) lists pemoline in the Schedule IV stimulants but does not name thozalinone. The WADA 2026 Prohibited List does not name thozalinone; it names pemoline in S6.B, the specified stimulants.

A 1982 analytical paper names thozalinone under the product name Stimsen. That shows only that a product was in use, not what its status was in any country. No approval record in any country was reviewed beyond these US and WADA records.

PubChem record: C11H12N2O2, the N,N-dimethyl analog of pemoline

Chemical identity record

PubChem, National Library of Medicine. Compound summary for CID 12602, thozalinone; pemoline is CID 4723.

Thozalinone is PubChem CID 12602, C11H12N2O2, molecular weight 204.22, IUPAC name 2-(dimethylamino)-5-phenyl-1,3-oxazol-4-one, with CAS 655-05-0 listed as a CAS-format synonym. Synonyms include Tozalinone, CL 39808, CL-39808 and NSC-170962. It is the N,N-dimethyl analog of pemoline (PubChem CID 4723, 2-amino-5-phenyl-1,3-oxazol-4-one, C9H8N2O2, molecular weight 176.17). A 1982 analytical paper groups pemoline, fenozolone and thozalinone as psychostimulants that share a hydrolysis product, 5-phenyl-2,4-oxazolidinedione. The title of the 1966 trial writes the code as C1 39,808, a typographic variant of CL 39,808.

Participants / model
Chemical identity, not a clinical population
Treatment
Defined molecule
Follow-up
Not applicable
Study design
Chemical database record
Funding
not stated in the source

Identity and relation to pemoline only. It gives no pharmacology, dose or safety information.

Read the original source
No US label, scheduling or enforcement record names thozalinone; WADA names pemoline, not thozalinone

Regulatory record

U.S. Food and Drug Administration: openFDA Drugs@FDA, DailyMed and the Health Fraud Product Database. Electronic Code of Federal Regulations, 21 CFR Part 1308, version of 6 October 2026. World Anti-Doping Agency, the 2026 Prohibited List, in effect from 1 January 2026. Searches run on 10 October 2026.

The WADA 2026 Prohibited List does not name thozalinone; it names pemoline in S6.B, the specified stimulants. openFDA Drugs@FDA queries by substance, generic and brand name for thozalinone returned no match on 10 October 2026, DailyMed returned 0 labels, and FDA's Health Fraud Product Database (2,213 entries, current as of 5 October 2026) has no entry naming it. 21 CFR Part 1308 (eCFR version of 6 October 2026) lists pemoline in the Schedule IV stimulants but does not name thozalinone. No approval record in any country was reviewed beyond these US and WADA records.

Participants / model
Athletes under the World Anti-Doping Code; US regulatory databases
Treatment
Not applicable
Follow-up
2026 List in effect from 1 January 2026; searches run on 10 October 2026
Study design
Official anti-doping list and regulator databases
Funding
not stated in the source

An absence in the records searched, not a legal-status finding for any country. The WADA wording comes from the 2026 list document; the linked page is the eCFR text.

Read the original source
1982 detection paper: thozalinone sold as Stimsen, a product that existed

Chemical identity record

Gielsdorf W. J Clin Chem Clin Biochem. 1982;20(2):65-8. PMID 6121837.

A 1982 analytical paper in the Journal of Clinical Chemistry and Clinical Biochemistry (Gielsdorf) names pemoline (Tradon), fenozolone (Ordinator) and thozalinone (Stimsen) as psychostimulants that are hard to detect in urine, converts them by acid hydrolysis to 5-phenyl-2,4-oxazolidinedione, and quantifies by thin-layer chromatography and GC-MS. It shows only that a product named Stimsen was in use, not what its status was in any country.

Participants / model
Human urine samples (analytical)
Treatment
Acid hydrolysis, TLC, GC-MS
Follow-up
not stated in the source
Study design
Original analytical study
Funding
not stated in the source

A detection assay. The urine level in its abstract concerns pemoline, not thozalinone.

Read the original source

What has been published about thozalinone?

Thozalinone has 1960s rodent papers, two human trial records (depression in 1966, obesity in 1971) and two 1980s mouse studies that used it as a dopamine tool. Four of the seven PubMed records have no abstract, so no human result, dose or sample size can be stated, and nothing measures wakefulness or motivation.

Greenblatt and Osterberg, Toxicology and Applied Pharmacology 1965 (volume 7, issue 4, pages 566 to 578), is titled Some pharmacologic properties of thozalinone, a new excitant. PubMed has no abstract; its indexing terms (amphetamine, appetite, central nervous system stimulants, liver, mice, rats, monoamine oxidase, reserpine, seizures, tetrabenazine, comparative study) indicate comparison with amphetamine in mice and rats, but no dose or effect size is retrievable. Berstein and Latimer, Psychopharmacologia 1968 (volume 12, issue 4, pages 338 to 345), studied the interaction of imipramine and desipramine with amphetamine, alpha-pipradrol, methylphenidate and thozalinone on behavioral facilitation; PubMed indexes it under rats and avoidance learning and has no abstract. Only the PubMed records were used for these two papers.

Gallant and five co-authors, Current Therapeutic Research 1966 (volume 8, issue 12, pages 621 to 622), report A double-blind study of thozalinone (C1 39,808) in depressed outpatients; indexing terms are adult, male, female, depression, antidepressive agents and placebos. Leite and colleagues, Revista Brasileira de Medicina 1971 (volume 28, issue 9, pages 475 to 478), report a Clinical trial of Stimsem Thozalinone in the treatment of obese patients, in Portuguese; indexing terms are obesity, appetite depressants and age groups from child to middle aged. Neither record has an abstract, so no result, dose, sample size or adverse event can be stated, and neither title names wakefulness or motivation as an endpoint.

Thozalinone later served as a research tool in mice. A 1980 study of mice fed neuroleptic drugs used thozalinone, which the authors call a dopaminergic stimulant, at 50 mg/kg intraperitoneally to elicit gnawing behavior; after 4 weeks of haloperidol, chlorpromazine, trifluoperazine or thioridazine, gnawing rose to 80%, 80%, 100% and 100% against 50% in controls, and clozapine did not change it. A 1985 study in ICR male mice (10 per dose level) gave five neuroleptics 30 minutes before DL-DOPA, apomorphine, amphetamine or thozalinone at 100 mg/kg intraperitoneally and found that neuroleptic drugs inhibit the gnawing or biting each agent induces, with thozalinone giving the best prediction of the drugs' parkinsonism-inducing potencies. These are dopamine-linked behavior findings at high doses. They do not measure wakefulness or motivation.

PubMed searches on 10 October 2026: thozalinone returned 7 records, all described above, and the names tozalinone, tozalinona, Stimsen and Stimsem returned the same 7. The code searches CL-39808, CL 39808 and CL39808 returned 4 unrelated records (a bacterial species description, a cannabidiol cell paper, an Ebola antibody paper and a hantavirus paper), and the phrases 2-dimethylamino-5-phenyl and 2-(dimethylamino)-5-phenyl returned 2 unrelated records. ClinicalTrials.gov returned 0 studies for thozalinone, tozalinone and Stimsen. No retrievable record measures wakefulness, vigilance, alertness, motivation or sleep deprivation with thozalinone in any species, and none gives pharmacokinetics or a toxicity figure for it.

1960s rodent papers: excitant compared with amphetamine per indexing terms, no abstracts

Animal study

Greenblatt EN et al. Toxicol Appl Pharmacol. 1965;7(4):566-78. PMID 4378772.

Greenblatt and Osterberg, Toxicology and Applied Pharmacology 1965;7(4):566 to 578, is titled Some pharmacologic properties of thozalinone, a new excitant. PubMed has no abstract; its indexing terms (amphetamine, appetite, central nervous system stimulants, liver, mice, rats, monoamine oxidase, reserpine, seizures, tetrabenazine, comparative study) indicate comparison with amphetamine in mice and rats, but no dose or effect size is retrievable. Berstein and Latimer, Psychopharmacologia 1968;12(4):338 to 345 (PMID 4385109), studied the interaction of imipramine and desipramine with amphetamine, alpha-pipradrol, methylphenidate and thozalinone on behavioral facilitation; PubMed indexes it under rats and avoidance learning and has no abstract.

Participants / model
Mice and rats per PubMed indexing terms
Treatment
not stated in the source
Follow-up
not stated in the source
Study design
Original preclinical studies, no abstracts
Funding
not stated in the source

Only the PubMed records were used; neither paper itself was reviewed, so no result, dose or effect size is stated.

Read the original source
1966 double-blind study in depression and 1971 trial in obesity: no abstracts, no retrievable results

Clinical trial

Gallant DM et al. Curr Ther Res Clin Exp. 1966;8(12):621-2. PMID 4962734.

Gallant and five co-authors, Current Therapeutic Research 1966;8(12):621 to 622, report A double-blind study of thozalinone (C1 39,808) in depressed outpatients. PubMed has no abstract; indexing terms are adult, male, female, depression, antidepressive agents and placebos. Leite and colleagues, Revista Brasileira de Medicina 1971;28(9):475 to 478 (PMID 5139648), report a Clinical trial of Stimsem Thozalinone in the treatment of obese patients, in Portuguese; indexing terms are obesity, appetite depressants and age groups from child to middle aged. Neither record has an abstract, so no result, dose, sample size or adverse event can be stated, and neither title names wakefulness or motivation as an endpoint.

Participants / model
Depressed outpatients (1966); obese patients, with age groups from child to middle aged per indexing terms (1971)
Treatment
not stated in the source
Follow-up
not stated in the source
Study design
Original clinical studies, no abstracts
Funding
not stated in the source

Only the PubMed records were used; neither paper itself was reviewed, so no outcome is stated.

Read the original source
Two mouse studies, 1980 and 1985: thozalinone at 50 and 100 mg/kg used to provoke gnawing behavior

Animal study

Yen-Koo HC et al. Drug Chem Toxicol. 1985;8(6):495-502. PMID 2868876.

A 1980 study of mice fed neuroleptic drugs used thozalinone, which the authors call a dopaminergic stimulant, at 50 mg/kg intraperitoneally to elicit gnawing behavior; after 4 weeks of haloperidol, chlorpromazine, trifluoperazine or thioridazine, gnawing rose to 80%, 80%, 100% and 100% against 50% in controls, and clozapine did not change it (PMID 6112126). A 1985 study in ICR male mice (10 per dose level; this record, PMID 2868876) gave five neuroleptics 30 minutes before DL-DOPA, apomorphine, amphetamine or thozalinone at 100 mg/kg intraperitoneally and found that neuroleptic drugs inhibit the gnawing or biting each agent induces, with thozalinone giving the best prediction of the drugs' parkinsonism-inducing potencies.

Participants / model
Mice (ICR male mice, 10 per dose level, in the 1985 study)
Treatment
Thozalinone 50 and 100 mg/kg, intraperitoneal
Follow-up
4 weeks of neuroleptic feeding before testing in the 1980 study; not stated for the 1985 study
Study design
Original preclinical studies
Funding
not stated in the source

Dopamine-linked behavior findings at high doses. They do not measure wakefulness or motivation.

Read the original source
PubMed, 10 October 2026: 7 records for thozalinone, 4 without abstracts, none on wakefulness or motivation

PubMed search record

PubMed searches run on 10 October 2026 for thozalinone, its name and code variants and its chemical name, with ClinicalTrials.gov searches.

The term thozalinone returned 7 records: the 1965 and 1968 rodent papers, the two mouse gnawing studies, the 1966 and 1971 trial records and the 1982 detection paper. Four of the seven have no abstract. The names tozalinone, tozalinona, Stimsen and Stimsem returned the same 7. The combined code search CL-39808, CL 39808 and CL39808 returned 4 unrelated records (a bacterial species description, a cannabidiol cell paper, an Ebola antibody paper and a hantavirus paper), and the phrases 2-dimethylamino-5-phenyl and 2-(dimethylamino)-5-phenyl together returned 2 unrelated records. ClinicalTrials.gov returned 0 studies for thozalinone, tozalinone and Stimsen. No retrievable record measures wakefulness, vigilance, alertness, motivation or sleep deprivation with thozalinone in any species, and none gives pharmacokinetics or a toxicity figure for it.

Participants / model
Records reviewed, not a population
Treatment
Not applicable
Follow-up
Searches run on 10 October 2026
Study design
Dated literature and registry search
Funding
not stated in the source

An absence finding as of 10 October 2026, not proof that no unpublished or unindexed work exists.

Read the original source

What does the pemoline record say, and what does it not say?

Thozalinone is the N,N-dimethyl analog of pemoline, and pemoline carried a documented liver-injury signal. That signal is pemoline data: no indexed study tests whether thozalinone shares it, and none reports a liver or other safety finding for thozalinone.

A 1982 analytical paper groups pemoline, fenozolone and thozalinone as psychostimulants that share a hydrolysis product, 5-phenyl-2,4-oxazolidinedione. Thozalinone differs from pemoline by two methyl groups on the 2-amino group.

A review of reports sent to FDA between 1975 and 1996 found that in early-1970s premarketing trials of pemoline, hepatic abnormalities were noted in enzyme levels in 1% to 3% of youths on maintenance treatment, in 6 of 6 rechallenges and in 2 of 2 biopsies. From 1975 to 1989 the FDA received 12 cases of jaundice and 6 deaths in youths ascribed to pemoline hepatotoxicity.

These are pemoline data in youths given oral pemoline. No indexed study tests whether thozalinone shares this liver signal, and none reports a liver or other safety finding for thozalinone. Pemoline is on the WADA 2026 list in S6.B and in the Schedule IV stimulants in 21 CFR Part 1308; thozalinone is named in neither.

PubChem record: C11H12N2O2, the N,N-dimethyl analog of pemoline

Chemical identity record

PubChem, National Library of Medicine. Compound summary for CID 12602, thozalinone; pemoline is CID 4723.

Thozalinone is PubChem CID 12602, C11H12N2O2, molecular weight 204.22, IUPAC name 2-(dimethylamino)-5-phenyl-1,3-oxazol-4-one, with CAS 655-05-0 listed as a CAS-format synonym. Synonyms include Tozalinone, CL 39808, CL-39808 and NSC-170962. It is the N,N-dimethyl analog of pemoline (PubChem CID 4723, 2-amino-5-phenyl-1,3-oxazol-4-one, C9H8N2O2, molecular weight 176.17). A 1982 analytical paper groups pemoline, fenozolone and thozalinone as psychostimulants that share a hydrolysis product, 5-phenyl-2,4-oxazolidinedione. The title of the 1966 trial writes the code as C1 39,808, a typographic variant of CL 39,808.

Participants / model
Chemical identity, not a clinical population
Treatment
Defined molecule
Follow-up
Not applicable
Study design
Chemical database record
Funding
not stated in the source

Identity and relation to pemoline only. It gives no pharmacology, dose or safety information.

Read the original source
1982 detection paper: thozalinone sold as Stimsen, a product that existed

Chemical identity record

Gielsdorf W. J Clin Chem Clin Biochem. 1982;20(2):65-8. PMID 6121837.

A 1982 analytical paper in the Journal of Clinical Chemistry and Clinical Biochemistry (Gielsdorf) names pemoline (Tradon), fenozolone (Ordinator) and thozalinone (Stimsen) as psychostimulants that are hard to detect in urine, converts them by acid hydrolysis to 5-phenyl-2,4-oxazolidinedione, and quantifies by thin-layer chromatography and GC-MS. It shows only that a product named Stimsen was in use, not what its status was in any country.

Participants / model
Human urine samples (analytical)
Treatment
Acid hydrolysis, TLC, GC-MS
Follow-up
not stated in the source
Study design
Original analytical study
Funding
not stated in the source

A detection assay. The urine level in its abstract concerns pemoline, not thozalinone.

Read the original source
Pemoline liver signal: 12 jaundice cases and 6 deaths in youths reported to FDA, 1975 to 1989

Narrative review

Safer DJ et al. J Am Acad Child Adolesc Psychiatry. 2001;40(6):622-9. PMID 11392339.

A review of reports sent to FDA between 1975 and 1996 found that in early-1970s premarketing trials of pemoline, hepatic abnormalities were noted in enzyme levels in 1% to 3% of youths on maintenance treatment, in 6 of 6 rechallenges and in 2 of 2 biopsies. From 1975 to 1989 the FDA received 12 cases of jaundice and 6 deaths in youths ascribed to pemoline hepatotoxicity.

Participants / model
Youths given pemoline
Treatment
Oral pemoline
Follow-up
Reports from 1975 to 1996
Study design
Review of postmarketing reports
Funding
not stated in the source

Pemoline data, not thozalinone data. No indexed study tests whether thozalinone shares this liver signal, and none reports a liver or other safety finding for thozalinone.

Read the original source
No US label, scheduling or enforcement record names thozalinone; WADA names pemoline, not thozalinone

Regulatory record

U.S. Food and Drug Administration: openFDA Drugs@FDA, DailyMed and the Health Fraud Product Database. Electronic Code of Federal Regulations, 21 CFR Part 1308, version of 6 October 2026. World Anti-Doping Agency, the 2026 Prohibited List, in effect from 1 January 2026. Searches run on 10 October 2026.

The WADA 2026 Prohibited List does not name thozalinone; it names pemoline in S6.B, the specified stimulants. openFDA Drugs@FDA queries by substance, generic and brand name for thozalinone returned no match on 10 October 2026, DailyMed returned 0 labels, and FDA's Health Fraud Product Database (2,213 entries, current as of 5 October 2026) has no entry naming it. 21 CFR Part 1308 (eCFR version of 6 October 2026) lists pemoline in the Schedule IV stimulants but does not name thozalinone. No approval record in any country was reviewed beyond these US and WADA records.

Participants / model
Athletes under the World Anti-Doping Code; US regulatory databases
Treatment
Not applicable
Follow-up
2026 List in effect from 1 January 2026; searches run on 10 October 2026
Study design
Official anti-doping list and regulator databases
Funding
not stated in the source

An absence in the records searched, not a legal-status finding for any country. The WADA wording comes from the 2026 list document; the linked page is the eCFR text.

Read the original source

Does thozalinone promote wakefulness or motivation?

No retrievable record says so. Records call thozalinone an excitant or stimulant and used it for depression and obesity, but none reports wakefulness, vigilance, alertness, motivation or sleep deprivation.

A seller describes thozalinone as promoting wakefulness and motivation. The 1965 paper calls it a new excitant, a 1980 mouse paper calls it a dopaminergic stimulant, and the human trial titles name depression and obesity. None of the seven PubMed records reports an endpoint for wakefulness, vigilance, alertness, motivation or sleep deprivation.

The mouse gnawing studies gave 50 to 100 mg/kg intraperitoneally to elicit a dopamine-linked behavior, which is not a measure of wakefulness or motivation. The missing abstracts mean the 1960s and 1970s papers cannot be used to support either claim.

1960s rodent papers: excitant compared with amphetamine per indexing terms, no abstracts

Animal study

Greenblatt EN et al. Toxicol Appl Pharmacol. 1965;7(4):566-78. PMID 4378772.

Greenblatt and Osterberg, Toxicology and Applied Pharmacology 1965;7(4):566 to 578, is titled Some pharmacologic properties of thozalinone, a new excitant. PubMed has no abstract; its indexing terms (amphetamine, appetite, central nervous system stimulants, liver, mice, rats, monoamine oxidase, reserpine, seizures, tetrabenazine, comparative study) indicate comparison with amphetamine in mice and rats, but no dose or effect size is retrievable. Berstein and Latimer, Psychopharmacologia 1968;12(4):338 to 345 (PMID 4385109), studied the interaction of imipramine and desipramine with amphetamine, alpha-pipradrol, methylphenidate and thozalinone on behavioral facilitation; PubMed indexes it under rats and avoidance learning and has no abstract.

Participants / model
Mice and rats per PubMed indexing terms
Treatment
not stated in the source
Follow-up
not stated in the source
Study design
Original preclinical studies, no abstracts
Funding
not stated in the source

Only the PubMed records were used; neither paper itself was reviewed, so no result, dose or effect size is stated.

Read the original source
Two mouse studies, 1980 and 1985: thozalinone at 50 and 100 mg/kg used to provoke gnawing behavior

Animal study

Yen-Koo HC et al. Drug Chem Toxicol. 1985;8(6):495-502. PMID 2868876.

A 1980 study of mice fed neuroleptic drugs used thozalinone, which the authors call a dopaminergic stimulant, at 50 mg/kg intraperitoneally to elicit gnawing behavior; after 4 weeks of haloperidol, chlorpromazine, trifluoperazine or thioridazine, gnawing rose to 80%, 80%, 100% and 100% against 50% in controls, and clozapine did not change it (PMID 6112126). A 1985 study in ICR male mice (10 per dose level; this record, PMID 2868876) gave five neuroleptics 30 minutes before DL-DOPA, apomorphine, amphetamine or thozalinone at 100 mg/kg intraperitoneally and found that neuroleptic drugs inhibit the gnawing or biting each agent induces, with thozalinone giving the best prediction of the drugs' parkinsonism-inducing potencies.

Participants / model
Mice (ICR male mice, 10 per dose level, in the 1985 study)
Treatment
Thozalinone 50 and 100 mg/kg, intraperitoneal
Follow-up
4 weeks of neuroleptic feeding before testing in the 1980 study; not stated for the 1985 study
Study design
Original preclinical studies
Funding
not stated in the source

Dopamine-linked behavior findings at high doses. They do not measure wakefulness or motivation.

Read the original source
1966 double-blind study in depression and 1971 trial in obesity: no abstracts, no retrievable results

Clinical trial

Gallant DM et al. Curr Ther Res Clin Exp. 1966;8(12):621-2. PMID 4962734.

Gallant and five co-authors, Current Therapeutic Research 1966;8(12):621 to 622, report A double-blind study of thozalinone (C1 39,808) in depressed outpatients. PubMed has no abstract; indexing terms are adult, male, female, depression, antidepressive agents and placebos. Leite and colleagues, Revista Brasileira de Medicina 1971;28(9):475 to 478 (PMID 5139648), report a Clinical trial of Stimsem Thozalinone in the treatment of obese patients, in Portuguese; indexing terms are obesity, appetite depressants and age groups from child to middle aged. Neither record has an abstract, so no result, dose, sample size or adverse event can be stated, and neither title names wakefulness or motivation as an endpoint.

Participants / model
Depressed outpatients (1966); obese patients, with age groups from child to middle aged per indexing terms (1971)
Treatment
not stated in the source
Follow-up
not stated in the source
Study design
Original clinical studies, no abstracts
Funding
not stated in the source

Only the PubMed records were used; neither paper itself was reviewed, so no outcome is stated.

Read the original source
PubMed, 10 October 2026: 7 records for thozalinone, 4 without abstracts, none on wakefulness or motivation

PubMed search record

PubMed searches run on 10 October 2026 for thozalinone, its name and code variants and its chemical name, with ClinicalTrials.gov searches.

The term thozalinone returned 7 records: the 1965 and 1968 rodent papers, the two mouse gnawing studies, the 1966 and 1971 trial records and the 1982 detection paper. Four of the seven have no abstract. The names tozalinone, tozalinona, Stimsen and Stimsem returned the same 7. The combined code search CL-39808, CL 39808 and CL39808 returned 4 unrelated records (a bacterial species description, a cannabidiol cell paper, an Ebola antibody paper and a hantavirus paper), and the phrases 2-dimethylamino-5-phenyl and 2-(dimethylamino)-5-phenyl together returned 2 unrelated records. ClinicalTrials.gov returned 0 studies for thozalinone, tozalinone and Stimsen. No retrievable record measures wakefulness, vigilance, alertness, motivation or sleep deprivation with thozalinone in any species, and none gives pharmacokinetics or a toxicity figure for it.

Participants / model
Records reviewed, not a population
Treatment
Not applicable
Follow-up
Searches run on 10 October 2026
Study design
Dated literature and registry search
Funding
not stated in the source

An absence finding as of 10 October 2026, not proof that no unpublished or unindexed work exists.

Read the original source

How does thozalinone act?

Records call it an excitant and a dopaminergic stimulant, and mouse studies used it to elicit dopamine-dependent gnawing, but no retrievable abstract states a molecular mechanism.

The 1965 paper calls thozalinone a new excitant, and its indexing terms (amphetamine, monoamine oxidase, reserpine, tetrabenazine) point to comparison with amphetamine in mice and rats, but PubMed has no abstract and no result is retrievable. A 1980 mouse study calls it a dopaminergic stimulant, and the 1985 study found that neuroleptics inhibit the gnawing it induces, with thozalinone giving the best prediction of the neuroleptics' parkinsonism-inducing potencies.

Thozalinone is the N,N-dimethyl analog of pemoline, and the two share a hydrolysis product, 5-phenyl-2,4-oxazolidinedione. No retrievable abstract reports a receptor, transporter or enzyme result for thozalinone, and no record measures wakefulness, vigilance, alertness or motivation.

Two mouse studies, 1980 and 1985: thozalinone at 50 and 100 mg/kg used to provoke gnawing behavior

Animal study

Yen-Koo HC et al. Drug Chem Toxicol. 1985;8(6):495-502. PMID 2868876.

A 1980 study of mice fed neuroleptic drugs used thozalinone, which the authors call a dopaminergic stimulant, at 50 mg/kg intraperitoneally to elicit gnawing behavior; after 4 weeks of haloperidol, chlorpromazine, trifluoperazine or thioridazine, gnawing rose to 80%, 80%, 100% and 100% against 50% in controls, and clozapine did not change it (PMID 6112126). A 1985 study in ICR male mice (10 per dose level; this record, PMID 2868876) gave five neuroleptics 30 minutes before DL-DOPA, apomorphine, amphetamine or thozalinone at 100 mg/kg intraperitoneally and found that neuroleptic drugs inhibit the gnawing or biting each agent induces, with thozalinone giving the best prediction of the drugs' parkinsonism-inducing potencies.

Participants / model
Mice (ICR male mice, 10 per dose level, in the 1985 study)
Treatment
Thozalinone 50 and 100 mg/kg, intraperitoneal
Follow-up
4 weeks of neuroleptic feeding before testing in the 1980 study; not stated for the 1985 study
Study design
Original preclinical studies
Funding
not stated in the source

Dopamine-linked behavior findings at high doses. They do not measure wakefulness or motivation.

Read the original source
1960s rodent papers: excitant compared with amphetamine per indexing terms, no abstracts

Animal study

Greenblatt EN et al. Toxicol Appl Pharmacol. 1965;7(4):566-78. PMID 4378772.

Greenblatt and Osterberg, Toxicology and Applied Pharmacology 1965;7(4):566 to 578, is titled Some pharmacologic properties of thozalinone, a new excitant. PubMed has no abstract; its indexing terms (amphetamine, appetite, central nervous system stimulants, liver, mice, rats, monoamine oxidase, reserpine, seizures, tetrabenazine, comparative study) indicate comparison with amphetamine in mice and rats, but no dose or effect size is retrievable. Berstein and Latimer, Psychopharmacologia 1968;12(4):338 to 345 (PMID 4385109), studied the interaction of imipramine and desipramine with amphetamine, alpha-pipradrol, methylphenidate and thozalinone on behavioral facilitation; PubMed indexes it under rats and avoidance learning and has no abstract.

Participants / model
Mice and rats per PubMed indexing terms
Treatment
not stated in the source
Follow-up
not stated in the source
Study design
Original preclinical studies, no abstracts
Funding
not stated in the source

Only the PubMed records were used; neither paper itself was reviewed, so no result, dose or effect size is stated.

Read the original source
PubChem record: C11H12N2O2, the N,N-dimethyl analog of pemoline

Chemical identity record

PubChem, National Library of Medicine. Compound summary for CID 12602, thozalinone; pemoline is CID 4723.

Thozalinone is PubChem CID 12602, C11H12N2O2, molecular weight 204.22, IUPAC name 2-(dimethylamino)-5-phenyl-1,3-oxazol-4-one, with CAS 655-05-0 listed as a CAS-format synonym. Synonyms include Tozalinone, CL 39808, CL-39808 and NSC-170962. It is the N,N-dimethyl analog of pemoline (PubChem CID 4723, 2-amino-5-phenyl-1,3-oxazol-4-one, C9H8N2O2, molecular weight 176.17). A 1982 analytical paper groups pemoline, fenozolone and thozalinone as psychostimulants that share a hydrolysis product, 5-phenyl-2,4-oxazolidinedione. The title of the 1966 trial writes the code as C1 39,808, a typographic variant of CL 39,808.

Participants / model
Chemical identity, not a clinical population
Treatment
Defined molecule
Follow-up
Not applicable
Study design
Chemical database record
Funding
not stated in the source

Identity and relation to pemoline only. It gives no pharmacology, dose or safety information.

Read the original source
1982 detection paper: thozalinone sold as Stimsen, a product that existed

Chemical identity record

Gielsdorf W. J Clin Chem Clin Biochem. 1982;20(2):65-8. PMID 6121837.

A 1982 analytical paper in the Journal of Clinical Chemistry and Clinical Biochemistry (Gielsdorf) names pemoline (Tradon), fenozolone (Ordinator) and thozalinone (Stimsen) as psychostimulants that are hard to detect in urine, converts them by acid hydrolysis to 5-phenyl-2,4-oxazolidinedione, and quantifies by thin-layer chromatography and GC-MS. It shows only that a product named Stimsen was in use, not what its status was in any country.

Participants / model
Human urine samples (analytical)
Treatment
Acid hydrolysis, TLC, GC-MS
Follow-up
not stated in the source
Study design
Original analytical study
Funding
not stated in the source

A detection assay. The urine level in its abstract concerns pemoline, not thozalinone.

Read the original source

What is known about the safety of thozalinone?

Thozalinone's own safety is unstudied in the retrievable record. It is a close chemical relative of pemoline, which carried a documented liver-injury signal, and both human trial records lack abstracts, so no adverse event can be stated.

No retrievable record reports a safety finding for thozalinone. The 1966 and 1971 trial records have no abstract, so no adverse event, dose or sample size is stated, and no pharmacokinetic or toxicity figure exists for it.

The pemoline liver-injury signal described above is pemoline data. It matters because thozalinone is pemoline's N,N-dimethyl analog, and no indexed study tests whether the signal carries over.

The mouse studies gave 50 and 100 mg/kg intraperitoneally to provoke gnawing behavior, and no toxicity figure appears in the records. The status of the product Stimsen outside the United States was not reviewed.

1966 double-blind study in depression and 1971 trial in obesity: no abstracts, no retrievable results

Clinical trial

Gallant DM et al. Curr Ther Res Clin Exp. 1966;8(12):621-2. PMID 4962734.

Gallant and five co-authors, Current Therapeutic Research 1966;8(12):621 to 622, report A double-blind study of thozalinone (C1 39,808) in depressed outpatients. PubMed has no abstract; indexing terms are adult, male, female, depression, antidepressive agents and placebos. Leite and colleagues, Revista Brasileira de Medicina 1971;28(9):475 to 478 (PMID 5139648), report a Clinical trial of Stimsem Thozalinone in the treatment of obese patients, in Portuguese; indexing terms are obesity, appetite depressants and age groups from child to middle aged. Neither record has an abstract, so no result, dose, sample size or adverse event can be stated, and neither title names wakefulness or motivation as an endpoint.

Participants / model
Depressed outpatients (1966); obese patients, with age groups from child to middle aged per indexing terms (1971)
Treatment
not stated in the source
Follow-up
not stated in the source
Study design
Original clinical studies, no abstracts
Funding
not stated in the source

Only the PubMed records were used; neither paper itself was reviewed, so no outcome is stated.

Read the original source
Pemoline liver signal: 12 jaundice cases and 6 deaths in youths reported to FDA, 1975 to 1989

Narrative review

Safer DJ et al. J Am Acad Child Adolesc Psychiatry. 2001;40(6):622-9. PMID 11392339.

A review of reports sent to FDA between 1975 and 1996 found that in early-1970s premarketing trials of pemoline, hepatic abnormalities were noted in enzyme levels in 1% to 3% of youths on maintenance treatment, in 6 of 6 rechallenges and in 2 of 2 biopsies. From 1975 to 1989 the FDA received 12 cases of jaundice and 6 deaths in youths ascribed to pemoline hepatotoxicity.

Participants / model
Youths given pemoline
Treatment
Oral pemoline
Follow-up
Reports from 1975 to 1996
Study design
Review of postmarketing reports
Funding
not stated in the source

Pemoline data, not thozalinone data. No indexed study tests whether thozalinone shares this liver signal, and none reports a liver or other safety finding for thozalinone.

Read the original source
PubMed, 10 October 2026: 7 records for thozalinone, 4 without abstracts, none on wakefulness or motivation

PubMed search record

PubMed searches run on 10 October 2026 for thozalinone, its name and code variants and its chemical name, with ClinicalTrials.gov searches.

The term thozalinone returned 7 records: the 1965 and 1968 rodent papers, the two mouse gnawing studies, the 1966 and 1971 trial records and the 1982 detection paper. Four of the seven have no abstract. The names tozalinone, tozalinona, Stimsen and Stimsem returned the same 7. The combined code search CL-39808, CL 39808 and CL39808 returned 4 unrelated records (a bacterial species description, a cannabidiol cell paper, an Ebola antibody paper and a hantavirus paper), and the phrases 2-dimethylamino-5-phenyl and 2-(dimethylamino)-5-phenyl together returned 2 unrelated records. ClinicalTrials.gov returned 0 studies for thozalinone, tozalinone and Stimsen. No retrievable record measures wakefulness, vigilance, alertness, motivation or sleep deprivation with thozalinone in any species, and none gives pharmacokinetics or a toxicity figure for it.

Participants / model
Records reviewed, not a population
Treatment
Not applicable
Follow-up
Searches run on 10 October 2026
Study design
Dated literature and registry search
Funding
not stated in the source

An absence finding as of 10 October 2026, not proof that no unpublished or unindexed work exists.

Read the original source
Two mouse studies, 1980 and 1985: thozalinone at 50 and 100 mg/kg used to provoke gnawing behavior

Animal study

Yen-Koo HC et al. Drug Chem Toxicol. 1985;8(6):495-502. PMID 2868876.

A 1980 study of mice fed neuroleptic drugs used thozalinone, which the authors call a dopaminergic stimulant, at 50 mg/kg intraperitoneally to elicit gnawing behavior; after 4 weeks of haloperidol, chlorpromazine, trifluoperazine or thioridazine, gnawing rose to 80%, 80%, 100% and 100% against 50% in controls, and clozapine did not change it (PMID 6112126). A 1985 study in ICR male mice (10 per dose level; this record, PMID 2868876) gave five neuroleptics 30 minutes before DL-DOPA, apomorphine, amphetamine or thozalinone at 100 mg/kg intraperitoneally and found that neuroleptic drugs inhibit the gnawing or biting each agent induces, with thozalinone giving the best prediction of the drugs' parkinsonism-inducing potencies.

Participants / model
Mice (ICR male mice, 10 per dose level, in the 1985 study)
Treatment
Thozalinone 50 and 100 mg/kg, intraperitoneal
Follow-up
4 weeks of neuroleptic feeding before testing in the 1980 study; not stated for the 1985 study
Study design
Original preclinical studies
Funding
not stated in the source

Dopamine-linked behavior findings at high doses. They do not measure wakefulness or motivation.

Read the original source
No US label, scheduling or enforcement record names thozalinone; WADA names pemoline, not thozalinone

Regulatory record

U.S. Food and Drug Administration: openFDA Drugs@FDA, DailyMed and the Health Fraud Product Database. Electronic Code of Federal Regulations, 21 CFR Part 1308, version of 6 October 2026. World Anti-Doping Agency, the 2026 Prohibited List, in effect from 1 January 2026. Searches run on 10 October 2026.

The WADA 2026 Prohibited List does not name thozalinone; it names pemoline in S6.B, the specified stimulants. openFDA Drugs@FDA queries by substance, generic and brand name for thozalinone returned no match on 10 October 2026, DailyMed returned 0 labels, and FDA's Health Fraud Product Database (2,213 entries, current as of 5 October 2026) has no entry naming it. 21 CFR Part 1308 (eCFR version of 6 October 2026) lists pemoline in the Schedule IV stimulants but does not name thozalinone. No approval record in any country was reviewed beyond these US and WADA records.

Participants / model
Athletes under the World Anti-Doping Code; US regulatory databases
Treatment
Not applicable
Follow-up
2026 List in effect from 1 January 2026; searches run on 10 October 2026
Study design
Official anti-doping list and regulator databases
Funding
not stated in the source

An absence in the records searched, not a legal-status finding for any country. The WADA wording comes from the 2026 list document; the linked page is the eCFR text.

Read the original source

Why does thozalinone sit in D tier?

Thozalinone has real history: 1960s animal pharmacology, two human trials in depression and obesity, and a marketed product name. Every human record lacks an abstract and nothing measures wakefulness or motivation, so D fits.

The history keeps it above F: 1960s animal pharmacology, two human trial records, two mouse studies that used it as a dopamine tool, and a product name.

The missing abstracts, the absence of efficacy data for the supplier claim and the pemoline liver signal keep it below a stronger grade. Its own safety is unstudied in the retrievable record.

1960s rodent papers: excitant compared with amphetamine per indexing terms, no abstracts

Animal study

Greenblatt EN et al. Toxicol Appl Pharmacol. 1965;7(4):566-78. PMID 4378772.

Greenblatt and Osterberg, Toxicology and Applied Pharmacology 1965;7(4):566 to 578, is titled Some pharmacologic properties of thozalinone, a new excitant. PubMed has no abstract; its indexing terms (amphetamine, appetite, central nervous system stimulants, liver, mice, rats, monoamine oxidase, reserpine, seizures, tetrabenazine, comparative study) indicate comparison with amphetamine in mice and rats, but no dose or effect size is retrievable. Berstein and Latimer, Psychopharmacologia 1968;12(4):338 to 345 (PMID 4385109), studied the interaction of imipramine and desipramine with amphetamine, alpha-pipradrol, methylphenidate and thozalinone on behavioral facilitation; PubMed indexes it under rats and avoidance learning and has no abstract.

Participants / model
Mice and rats per PubMed indexing terms
Treatment
not stated in the source
Follow-up
not stated in the source
Study design
Original preclinical studies, no abstracts
Funding
not stated in the source

Only the PubMed records were used; neither paper itself was reviewed, so no result, dose or effect size is stated.

Read the original source
1966 double-blind study in depression and 1971 trial in obesity: no abstracts, no retrievable results

Clinical trial

Gallant DM et al. Curr Ther Res Clin Exp. 1966;8(12):621-2. PMID 4962734.

Gallant and five co-authors, Current Therapeutic Research 1966;8(12):621 to 622, report A double-blind study of thozalinone (C1 39,808) in depressed outpatients. PubMed has no abstract; indexing terms are adult, male, female, depression, antidepressive agents and placebos. Leite and colleagues, Revista Brasileira de Medicina 1971;28(9):475 to 478 (PMID 5139648), report a Clinical trial of Stimsem Thozalinone in the treatment of obese patients, in Portuguese; indexing terms are obesity, appetite depressants and age groups from child to middle aged. Neither record has an abstract, so no result, dose, sample size or adverse event can be stated, and neither title names wakefulness or motivation as an endpoint.

Participants / model
Depressed outpatients (1966); obese patients, with age groups from child to middle aged per indexing terms (1971)
Treatment
not stated in the source
Follow-up
not stated in the source
Study design
Original clinical studies, no abstracts
Funding
not stated in the source

Only the PubMed records were used; neither paper itself was reviewed, so no outcome is stated.

Read the original source
Two mouse studies, 1980 and 1985: thozalinone at 50 and 100 mg/kg used to provoke gnawing behavior

Animal study

Yen-Koo HC et al. Drug Chem Toxicol. 1985;8(6):495-502. PMID 2868876.

A 1980 study of mice fed neuroleptic drugs used thozalinone, which the authors call a dopaminergic stimulant, at 50 mg/kg intraperitoneally to elicit gnawing behavior; after 4 weeks of haloperidol, chlorpromazine, trifluoperazine or thioridazine, gnawing rose to 80%, 80%, 100% and 100% against 50% in controls, and clozapine did not change it (PMID 6112126). A 1985 study in ICR male mice (10 per dose level; this record, PMID 2868876) gave five neuroleptics 30 minutes before DL-DOPA, apomorphine, amphetamine or thozalinone at 100 mg/kg intraperitoneally and found that neuroleptic drugs inhibit the gnawing or biting each agent induces, with thozalinone giving the best prediction of the drugs' parkinsonism-inducing potencies.

Participants / model
Mice (ICR male mice, 10 per dose level, in the 1985 study)
Treatment
Thozalinone 50 and 100 mg/kg, intraperitoneal
Follow-up
4 weeks of neuroleptic feeding before testing in the 1980 study; not stated for the 1985 study
Study design
Original preclinical studies
Funding
not stated in the source

Dopamine-linked behavior findings at high doses. They do not measure wakefulness or motivation.

Read the original source
Pemoline liver signal: 12 jaundice cases and 6 deaths in youths reported to FDA, 1975 to 1989

Narrative review

Safer DJ et al. J Am Acad Child Adolesc Psychiatry. 2001;40(6):622-9. PMID 11392339.

A review of reports sent to FDA between 1975 and 1996 found that in early-1970s premarketing trials of pemoline, hepatic abnormalities were noted in enzyme levels in 1% to 3% of youths on maintenance treatment, in 6 of 6 rechallenges and in 2 of 2 biopsies. From 1975 to 1989 the FDA received 12 cases of jaundice and 6 deaths in youths ascribed to pemoline hepatotoxicity.

Participants / model
Youths given pemoline
Treatment
Oral pemoline
Follow-up
Reports from 1975 to 1996
Study design
Review of postmarketing reports
Funding
not stated in the source

Pemoline data, not thozalinone data. No indexed study tests whether thozalinone shares this liver signal, and none reports a liver or other safety finding for thozalinone.

Read the original source
PubMed, 10 October 2026: 7 records for thozalinone, 4 without abstracts, none on wakefulness or motivation

PubMed search record

PubMed searches run on 10 October 2026 for thozalinone, its name and code variants and its chemical name, with ClinicalTrials.gov searches.

The term thozalinone returned 7 records: the 1965 and 1968 rodent papers, the two mouse gnawing studies, the 1966 and 1971 trial records and the 1982 detection paper. Four of the seven have no abstract. The names tozalinone, tozalinona, Stimsen and Stimsem returned the same 7. The combined code search CL-39808, CL 39808 and CL39808 returned 4 unrelated records (a bacterial species description, a cannabidiol cell paper, an Ebola antibody paper and a hantavirus paper), and the phrases 2-dimethylamino-5-phenyl and 2-(dimethylamino)-5-phenyl together returned 2 unrelated records. ClinicalTrials.gov returned 0 studies for thozalinone, tozalinone and Stimsen. No retrievable record measures wakefulness, vigilance, alertness, motivation or sleep deprivation with thozalinone in any species, and none gives pharmacokinetics or a toxicity figure for it.

Participants / model
Records reviewed, not a population
Treatment
Not applicable
Follow-up
Searches run on 10 October 2026
Study design
Dated literature and registry search
Funding
not stated in the source

An absence finding as of 10 October 2026, not proof that no unpublished or unindexed work exists.

Read the original source

Studies and sources

PubChem record: C11H12N2O2, the N,N-dimethyl analog of pemoline

Chemical identity record

PubChem, National Library of Medicine. Compound summary for CID 12602, thozalinone; pemoline is CID 4723.

Thozalinone is PubChem CID 12602, C11H12N2O2, molecular weight 204.22, IUPAC name 2-(dimethylamino)-5-phenyl-1,3-oxazol-4-one, with CAS 655-05-0 listed as a CAS-format synonym. Synonyms include Tozalinone, CL 39808, CL-39808 and NSC-170962. It is the N,N-dimethyl analog of pemoline (PubChem CID 4723, 2-amino-5-phenyl-1,3-oxazol-4-one, C9H8N2O2, molecular weight 176.17). A 1982 analytical paper groups pemoline, fenozolone and thozalinone as psychostimulants that share a hydrolysis product, 5-phenyl-2,4-oxazolidinedione. The title of the 1966 trial writes the code as C1 39,808, a typographic variant of CL 39,808.

Participants / model
Chemical identity, not a clinical population
Treatment
Defined molecule
Follow-up
Not applicable
Study design
Chemical database record
Funding
not stated in the source

Identity and relation to pemoline only. It gives no pharmacology, dose or safety information.

Read the original source
1960s rodent papers: excitant compared with amphetamine per indexing terms, no abstracts

Animal study

Greenblatt EN et al. Toxicol Appl Pharmacol. 1965;7(4):566-78. PMID 4378772.

Greenblatt and Osterberg, Toxicology and Applied Pharmacology 1965;7(4):566 to 578, is titled Some pharmacologic properties of thozalinone, a new excitant. PubMed has no abstract; its indexing terms (amphetamine, appetite, central nervous system stimulants, liver, mice, rats, monoamine oxidase, reserpine, seizures, tetrabenazine, comparative study) indicate comparison with amphetamine in mice and rats, but no dose or effect size is retrievable. Berstein and Latimer, Psychopharmacologia 1968;12(4):338 to 345 (PMID 4385109), studied the interaction of imipramine and desipramine with amphetamine, alpha-pipradrol, methylphenidate and thozalinone on behavioral facilitation; PubMed indexes it under rats and avoidance learning and has no abstract.

Participants / model
Mice and rats per PubMed indexing terms
Treatment
not stated in the source
Follow-up
not stated in the source
Study design
Original preclinical studies, no abstracts
Funding
not stated in the source

Only the PubMed records were used; neither paper itself was reviewed, so no result, dose or effect size is stated.

Read the original source
Two mouse studies, 1980 and 1985: thozalinone at 50 and 100 mg/kg used to provoke gnawing behavior

Animal study

Yen-Koo HC et al. Drug Chem Toxicol. 1985;8(6):495-502. PMID 2868876.

A 1980 study of mice fed neuroleptic drugs used thozalinone, which the authors call a dopaminergic stimulant, at 50 mg/kg intraperitoneally to elicit gnawing behavior; after 4 weeks of haloperidol, chlorpromazine, trifluoperazine or thioridazine, gnawing rose to 80%, 80%, 100% and 100% against 50% in controls, and clozapine did not change it (PMID 6112126). A 1985 study in ICR male mice (10 per dose level; this record, PMID 2868876) gave five neuroleptics 30 minutes before DL-DOPA, apomorphine, amphetamine or thozalinone at 100 mg/kg intraperitoneally and found that neuroleptic drugs inhibit the gnawing or biting each agent induces, with thozalinone giving the best prediction of the drugs' parkinsonism-inducing potencies.

Participants / model
Mice (ICR male mice, 10 per dose level, in the 1985 study)
Treatment
Thozalinone 50 and 100 mg/kg, intraperitoneal
Follow-up
4 weeks of neuroleptic feeding before testing in the 1980 study; not stated for the 1985 study
Study design
Original preclinical studies
Funding
not stated in the source

Dopamine-linked behavior findings at high doses. They do not measure wakefulness or motivation.

Read the original source
1966 double-blind study in depression and 1971 trial in obesity: no abstracts, no retrievable results

Clinical trial

Gallant DM et al. Curr Ther Res Clin Exp. 1966;8(12):621-2. PMID 4962734.

Gallant and five co-authors, Current Therapeutic Research 1966;8(12):621 to 622, report A double-blind study of thozalinone (C1 39,808) in depressed outpatients. PubMed has no abstract; indexing terms are adult, male, female, depression, antidepressive agents and placebos. Leite and colleagues, Revista Brasileira de Medicina 1971;28(9):475 to 478 (PMID 5139648), report a Clinical trial of Stimsem Thozalinone in the treatment of obese patients, in Portuguese; indexing terms are obesity, appetite depressants and age groups from child to middle aged. Neither record has an abstract, so no result, dose, sample size or adverse event can be stated, and neither title names wakefulness or motivation as an endpoint.

Participants / model
Depressed outpatients (1966); obese patients, with age groups from child to middle aged per indexing terms (1971)
Treatment
not stated in the source
Follow-up
not stated in the source
Study design
Original clinical studies, no abstracts
Funding
not stated in the source

Only the PubMed records were used; neither paper itself was reviewed, so no outcome is stated.

Read the original source
1982 detection paper: thozalinone sold as Stimsen, a product that existed

Chemical identity record

Gielsdorf W. J Clin Chem Clin Biochem. 1982;20(2):65-8. PMID 6121837.

A 1982 analytical paper in the Journal of Clinical Chemistry and Clinical Biochemistry (Gielsdorf) names pemoline (Tradon), fenozolone (Ordinator) and thozalinone (Stimsen) as psychostimulants that are hard to detect in urine, converts them by acid hydrolysis to 5-phenyl-2,4-oxazolidinedione, and quantifies by thin-layer chromatography and GC-MS. It shows only that a product named Stimsen was in use, not what its status was in any country.

Participants / model
Human urine samples (analytical)
Treatment
Acid hydrolysis, TLC, GC-MS
Follow-up
not stated in the source
Study design
Original analytical study
Funding
not stated in the source

A detection assay. The urine level in its abstract concerns pemoline, not thozalinone.

Read the original source
Pemoline liver signal: 12 jaundice cases and 6 deaths in youths reported to FDA, 1975 to 1989

Narrative review

Safer DJ et al. J Am Acad Child Adolesc Psychiatry. 2001;40(6):622-9. PMID 11392339.

A review of reports sent to FDA between 1975 and 1996 found that in early-1970s premarketing trials of pemoline, hepatic abnormalities were noted in enzyme levels in 1% to 3% of youths on maintenance treatment, in 6 of 6 rechallenges and in 2 of 2 biopsies. From 1975 to 1989 the FDA received 12 cases of jaundice and 6 deaths in youths ascribed to pemoline hepatotoxicity.

Participants / model
Youths given pemoline
Treatment
Oral pemoline
Follow-up
Reports from 1975 to 1996
Study design
Review of postmarketing reports
Funding
not stated in the source

Pemoline data, not thozalinone data. No indexed study tests whether thozalinone shares this liver signal, and none reports a liver or other safety finding for thozalinone.

Read the original source
No US label, scheduling or enforcement record names thozalinone; WADA names pemoline, not thozalinone

Regulatory record

U.S. Food and Drug Administration: openFDA Drugs@FDA, DailyMed and the Health Fraud Product Database. Electronic Code of Federal Regulations, 21 CFR Part 1308, version of 6 October 2026. World Anti-Doping Agency, the 2026 Prohibited List, in effect from 1 January 2026. Searches run on 10 October 2026.

The WADA 2026 Prohibited List does not name thozalinone; it names pemoline in S6.B, the specified stimulants. openFDA Drugs@FDA queries by substance, generic and brand name for thozalinone returned no match on 10 October 2026, DailyMed returned 0 labels, and FDA's Health Fraud Product Database (2,213 entries, current as of 5 October 2026) has no entry naming it. 21 CFR Part 1308 (eCFR version of 6 October 2026) lists pemoline in the Schedule IV stimulants but does not name thozalinone. No approval record in any country was reviewed beyond these US and WADA records.

Participants / model
Athletes under the World Anti-Doping Code; US regulatory databases
Treatment
Not applicable
Follow-up
2026 List in effect from 1 January 2026; searches run on 10 October 2026
Study design
Official anti-doping list and regulator databases
Funding
not stated in the source

An absence in the records searched, not a legal-status finding for any country. The WADA wording comes from the 2026 list document; the linked page is the eCFR text.

Read the original source
PubMed, 10 October 2026: 7 records for thozalinone, 4 without abstracts, none on wakefulness or motivation

PubMed search record

PubMed searches run on 10 October 2026 for thozalinone, its name and code variants and its chemical name, with ClinicalTrials.gov searches.

The term thozalinone returned 7 records: the 1965 and 1968 rodent papers, the two mouse gnawing studies, the 1966 and 1971 trial records and the 1982 detection paper. Four of the seven have no abstract. The names tozalinone, tozalinona, Stimsen and Stimsem returned the same 7. The combined code search CL-39808, CL 39808 and CL39808 returned 4 unrelated records (a bacterial species description, a cannabidiol cell paper, an Ebola antibody paper and a hantavirus paper), and the phrases 2-dimethylamino-5-phenyl and 2-(dimethylamino)-5-phenyl together returned 2 unrelated records. ClinicalTrials.gov returned 0 studies for thozalinone, tozalinone and Stimsen. No retrievable record measures wakefulness, vigilance, alertness, motivation or sleep deprivation with thozalinone in any species, and none gives pharmacokinetics or a toxicity figure for it.

Participants / model
Records reviewed, not a population
Treatment
Not applicable
Follow-up
Searches run on 10 October 2026
Study design
Dated literature and registry search
Funding
not stated in the source

An absence finding as of 10 October 2026, not proof that no unpublished or unindexed work exists.

Read the original source

Why is Thozalinone in D tier?

D fits real history with thin evidence: 1960s animal pharmacology, two human trial records and a product name, but no retrievable result and no measurement of wakefulness or motivation. The pemoline liver signal and thozalinone's own unstudied safety keep it below a stronger grade.