PRL-8-53

updated

PRL-8-53 is a methyl benzoate research compound sold for acute memory. One 1978 study in people, co-authored by the compound's originator, reports improved retention of verbal information after low oral doses. The abstract gives no number of subjects or dose, nothing has replicated the result, and no safety or pharmacokinetic data exist.

Methyl benzoate amine (research compound)

  • PRL-8-53 is methyl 3-[2-[benzyl(methyl)amino]ethyl]benzoate, studied as the hydrochloride (molecular weight 319.8); the free base is a separate record (283.4).
  • The one human study (Hansl and Mead, 1978) was double-blind and placebo-compared per its abstract and reported slight improvement of acquisition and better retention of verbal information after low oral doses.
  • The abstract gives no number of subjects, dose, number of sessions, design or retention interval, and its P values are not an effect size.
  • The compound's originator, Nikolaus R. Hansl, introduced it in 1974 and co-authored the 1978 study; no independent human study was found.
  • A PubMed search on 10 October 2026 for PRL-8-53 returned 1 record, and ClinicalTrials.gov returned 0 studies.

What is PRL-8-53, and what is its regulatory status?

PRL-8-53 is methyl 3-[2-[benzyl(methyl)amino]ethyl]benzoate, studied as the hydrochloride. No US approval, label, scheduling or enforcement record names it, and the WADA 2026 list does not name it.

PRL-8-53 is methyl 3-[2-[benzyl(methyl)amino]ethyl]benzoate, studied as the hydrochloride. PubChem CID 70700868 is the hydrochloride: C18H22ClNO2, molecular weight 319.8, CAS 51352-87-5 (a CAS-format synonym), with the synonym PRL-8-53 (hydrochloride). The free base is a separate record, CID 39989: C18H21NO2, molecular weight 283.4, CAS 51352-88-6, listed as PRL-8-53 free base. The 1978 human paper names the compound as 3-(2-benzylmethylaminoethyl) benzoic acid methyl ester hydrochloride. The salt weighs 36.4 mass units more than the base (319.8 minus 283.4), so any dose figure depends on which form it refers to.

The WADA 2026 Prohibited List does not name PRL-8-53. Section S0 prohibits at all times any pharmacological substance not addressed elsewhere on the List and with no current approval for human therapeutic use, but no source reviewed says WADA has applied it to this compound. On 10 October 2026 openFDA Drugs@FDA queries by substance, generic and brand name returned no match, a DailyMed search returned 0 labels, 21 CFR Part 1308 (eCFR version of 6 October 2026) does not name it, and FDA's Health Fraud Product Database (2,213 entries, current as of 5 October 2026) has no entry naming it. No approval, scheduling or enforcement record was found, and no toxicity or adverse-event report is retrievable from the records reviewed.

PubChem records: hydrochloride 319.8, free base 283.4, two separate compounds

Chemical identity record

PubChem, National Library of Medicine. Compound summary for CID 70700868, PRL-8-53 hydrochloride; the free base is CID 39989.

PRL-8-53 is methyl 3-[2-[benzyl(methyl)amino]ethyl]benzoate, studied as the hydrochloride. PubChem CID 70700868 is the hydrochloride: C18H22ClNO2, molecular weight 319.8, CAS 51352-87-5 (a CAS-format synonym), with the synonym PRL-8-53 (hydrochloride). The free base is a separate record, CID 39989: C18H21NO2, molecular weight 283.4, CAS 51352-88-6, listed as PRL-8-53 free base. The 1978 human paper names the compound as 3-(2-benzylmethylaminoethyl) benzoic acid methyl ester hydrochloride. The salt weighs 36.4 mass units more than the base (319.8 minus 283.4), so any dose figure depends on which form it refers to.

Participants / model
Chemical identity, not a clinical population
Treatment
Defined molecule; hydrochloride salt and free base are separate records
Follow-up
Not applicable
Study design
Chemical database record
Funding
not stated in the source

Identity and salt form only. It gives no pharmacology, dose or safety information.

Read the original source
WADA 2026 list does not name PRL-8-53; no US approval, scheduling or enforcement record

Regulatory record

World Anti-Doping Agency. The 2026 Prohibited List, in effect from 1 January 2026. 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. Searches run on 10 October 2026.

The WADA 2026 Prohibited List does not name PRL-8-53. S0 prohibits at all times any pharmacological substance not addressed elsewhere on the List and with no current approval for human therapeutic use, but no source reviewed says WADA has applied it to this compound. openFDA Drugs@FDA queries by substance, generic and brand name returned no match on 10 October 2026, a DailyMed search returned 0 labels, 21 CFR Part 1308 (eCFR version of 6 October 2026) does not name it, and FDA's Health Fraud Product Database (2,213 entries, current as of 5 October 2026) has no entry naming it. No approval, scheduling or enforcement record was found, and no toxicity or adverse-event report is retrievable from the records reviewed.

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.

Read the original source

What did the one published study in people find?

One 1978 double-blind study in an unstated number of people reported slight improvement of acquisition and statistically significant improvement of retention of verbal information after low oral doses, with no significant change in visual reaction time or motor control against placebo. Its size, doses and design are not stated in the abstract.

Hansl and Mead published the study in Psychopharmacology in 1978 (volume 56, issue 3, pages 249 to 253). It examined the effect of PRL-8-53 on learning and on retention of verbal information in human subjects. Using the serial anticipation method under double-blind conditions, PRL-8-53 caused slight improvement of acquisition. Retention of verbal information improved to a statistically significant degree, with most P values better than 0.01 and some better than 0.001. Visual reaction time and motor control showed no significant change against placebo. The title says the doses were low and oral.

The abstract does not give the number of subjects, the dose, the number of sessions, the age or sex of participants, whether the design was crossover or parallel, the retention interval, or whether dosing was single or repeated. PubMed indexes the paper under the publication types randomized controlled trial, controlled clinical trial and clinical trial, which are indexing labels and not a description of the design. Only the abstract was reviewed, so size and design beyond double-blind, placebo-compared, serial anticipation are not established, and the P values are not an effect size.

The one human study, 1978: slightly better acquisition, better retention of verbal information; size and design not stated

Human study

Hansl NR et al. Psychopharmacology (Berl). 1978;56(3):249-53. PMID 418433.

Hansl and Mead, Psychopharmacology 1978;56(3):249 to 253, studied the effect of PRL-8-53 on learning and on retention of verbal information in human subjects. Using the serial anticipation method under double-blind conditions, PRL-8-53 caused slight improvement of acquisition. Retention of verbal information improved to a statistically significant degree (most P values better than 0.01, some better than 0.001). Visual reaction time and motor control showed no significant change against placebo. The title says the doses were low and oral. The abstract does not give the number of subjects, the dose, the number of sessions, the age or sex of participants, whether the design was crossover or parallel, the retention interval, or whether dosing was single or repeated.

Participants / model
Human subjects, number not stated in the abstract
Treatment
Oral, low doses per the title; hydrochloride
Follow-up
not stated in the source
Study design
Original controlled study, abstract only; double-blind and placebo-compared per the abstract
Funding
not stated in the source

PubMed indexes the paper under the publication types randomized controlled trial, controlled clinical trial and clinical trial, which are indexing labels and not a description of the design. The full text is behind a paywall and was not reviewed, so size and design beyond double-blind, placebo-compared, serial anticipation are not established. The P values are not an effect size.

Read the original source

Who first described PRL-8-53, and has anyone else tested it?

Nikolaus R. Hansl first described the compound in 1974 and co-authored the only human study in 1978, so the human result comes from the originator's group. No independent human study, replication or registered study was found.

Springer's page for the 1978 paper lists the authors, Nikolaus R. Hansl and Beverley T. Mead, at the Department of Medicinal Chemistry and the Department of Psychiatry, Creighton University, Omaha, Nebraska. Hansl is also the sole author of the 1974 report that introduced the compound, whose Springer page lists Creighton University and Pacific Research Laboratories, Santa Barbara, California. PubMed's own record for the 1978 paper carries no affiliation.

The 1974 report, Hansl, Experientia 1974, pages 271 to 272, is titled A novel spasmolytic and CNS active agent and names the same compound. PubMed carries no abstract for it. Its indexing terms (animals, rats, dogs, learning, avoidance learning, motor activity, blood pressure, heart rate, seizures, apomorphine, methamphetamine, parasympatholytics) indicate animal pharmacology, but no dose, effect size or toxicity figure can be taken from the record.

PubMed searches on 10 October 2026 for PRL-8-53 returned 1 record, the 1978 paper, and so did PRL 8-53; PRL8-53 returned 0. A search for Hansl as author returned 3 records: the 1974 and 1978 PRL-8-53 papers and an unrelated 1977 Clinical Toxicology paper on papaverine and isoproterenol in dog vessels and rabbit intestine. ClinicalTrials.gov returned 0 studies for PRL-8-53. In the records reviewed, no second human study, replication, dose-response study, pharmacokinetic study or single-dose test exists, and no study confirms the effect in people other than its originator's group.

Publisher page: the 1978 co-author is the compound's originator, at Creighton University

Human study

Hansl NR, Mead BT. Psychopharmacology. 1978;56(3):249-253. Springer article page, doi 10.1007/BF00432846.

Springer's page for the 1978 paper lists the authors, Nikolaus R. Hansl and Beverley T. Mead, at the Department of Medicinal Chemistry and the Department of Psychiatry, Creighton University, Omaha, Nebraska. Hansl is also the sole author of the 1974 report that introduced the compound, whose Springer page lists Creighton University and Pacific Research Laboratories, Santa Barbara, California. So the person who first described the compound co-authored the only human study. PubMed's own record for the 1978 paper carries no affiliation. No independent human study was found.

Participants / model
Not a clinical population
Treatment
Not applicable
Follow-up
Not applicable
Study design
Journal publisher page (authorship and affiliations)
Funding
not stated in the source

Affiliations were read from the publisher pages and not confirmed against the printed paper.

Read the original source
1974 report that introduced the compound: animal pharmacology per indexing terms, no abstract

Animal study

Hansl NR. Experientia. 1974;30(3):271-2. PMID 4824605.

Hansl, Experientia 1974;30(3):271 to 272, is titled A novel spasmolytic and CNS active agent and names the same compound. PubMed carries no abstract for this two-page paper. Its indexing terms (animals, rats, dogs, learning, avoidance learning, motor activity, blood pressure, heart rate, seizures, apomorphine, methamphetamine, parasympatholytics) indicate animal pharmacology, but no dose, effect size or toxicity figure can be taken from the record.

Participants / model
Rats and dogs per PubMed indexing terms; abstract not available
Treatment
not stated in the source
Follow-up
not stated in the source
Study design
Original preclinical report, no abstract
Funding
not stated in the source

The paper itself was not reviewed. Only the PubMed record and its indexing terms were used.

Read the original source
PubMed, 10 October 2026: 1 record for PRL-8-53, no replication, no registered study

PubMed search record

PubMed searches run on 10 October 2026 for PRL-8-53 and its spelling variants, for Hansl as author, and for learning and retention studies in humans in 1978, with a ClinicalTrials.gov search.

PRL-8-53 returned 1 record, the 1978 human paper, and so did PRL 8-53; PRL8-53 returned 0; the combined variants PRL-8-53, PRL 8-53, PRL8-53 and PRL-853 returned 1. A search for Hansl NR as author returned 3 records: the 1974 and 1978 PRL-8-53 papers and a 1977 Clinical Toxicology paper on papaverine and isoproterenol in dog vessels and rabbit intestine, which is unrelated. A search for nootropic or psychotropic with learning, retention, humans, oral and the year 1978 returned only the 1978 paper. ClinicalTrials.gov returned 0 studies for PRL-8-53. In the records reviewed, no second human study, replication, dose-response study, pharmacokinetic study or single-dose test exists, and no study confirms the effect in people other than its originator's group.

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

Does PRL-8-53 improve acute memory?

Partly supported, and only for retention of verbal information. The 1978 abstract reports improved retention after low oral doses in human subjects, but it does not say the effect is acute or single-dose, the sample size is unknown, and no one has replicated it.

A vendor says PRL-8-53 improves acute memory. The 1978 abstract supports improved retention of verbal information after low oral doses in human subjects. It does not say the effect is acute or a single-dose effect, it does not give the sample size, and no other human study has tested it.

Acquisition improved only slightly in that study, visual reaction time and motor control did not change significantly against placebo, and the P values reported are not an effect size.

The one human study, 1978: slightly better acquisition, better retention of verbal information; size and design not stated

Human study

Hansl NR et al. Psychopharmacology (Berl). 1978;56(3):249-53. PMID 418433.

Hansl and Mead, Psychopharmacology 1978;56(3):249 to 253, studied the effect of PRL-8-53 on learning and on retention of verbal information in human subjects. Using the serial anticipation method under double-blind conditions, PRL-8-53 caused slight improvement of acquisition. Retention of verbal information improved to a statistically significant degree (most P values better than 0.01, some better than 0.001). Visual reaction time and motor control showed no significant change against placebo. The title says the doses were low and oral. The abstract does not give the number of subjects, the dose, the number of sessions, the age or sex of participants, whether the design was crossover or parallel, the retention interval, or whether dosing was single or repeated.

Participants / model
Human subjects, number not stated in the abstract
Treatment
Oral, low doses per the title; hydrochloride
Follow-up
not stated in the source
Study design
Original controlled study, abstract only; double-blind and placebo-compared per the abstract
Funding
not stated in the source

PubMed indexes the paper under the publication types randomized controlled trial, controlled clinical trial and clinical trial, which are indexing labels and not a description of the design. The full text is behind a paywall and was not reviewed, so size and design beyond double-blind, placebo-compared, serial anticipation are not established. The P values are not an effect size.

Read the original source
PubMed, 10 October 2026: 1 record for PRL-8-53, no replication, no registered study

PubMed search record

PubMed searches run on 10 October 2026 for PRL-8-53 and its spelling variants, for Hansl as author, and for learning and retention studies in humans in 1978, with a ClinicalTrials.gov search.

PRL-8-53 returned 1 record, the 1978 human paper, and so did PRL 8-53; PRL8-53 returned 0; the combined variants PRL-8-53, PRL 8-53, PRL8-53 and PRL-853 returned 1. A search for Hansl NR as author returned 3 records: the 1974 and 1978 PRL-8-53 papers and a 1977 Clinical Toxicology paper on papaverine and isoproterenol in dog vessels and rabbit intestine, which is unrelated. A search for nootropic or psychotropic with learning, retention, humans, oral and the year 1978 returned only the 1978 paper. ClinicalTrials.gov returned 0 studies for PRL-8-53. In the records reviewed, no second human study, replication, dose-response study, pharmacokinetic study or single-dose test exists, and no study confirms the effect in people other than its originator's group.

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 PRL-8-53 act?

Not established. The only animal work is a 1974 report with no retrievable abstract, and the 1978 human abstract reports behavioral outcomes only.

No record reviewed reports how PRL-8-53 acts. The 1974 report calls it a spasmolytic and CNS active agent, and its indexing terms point to rat and dog pharmacology, but the record has no abstract, so no mechanism, dose or effect size can be taken from it.

The 1978 human abstract reports acquisition, retention of verbal information, visual reaction time and motor control, and no pharmacological mechanism. No pharmacokinetic study, dose-response study or single-dose test exists in the records reviewed.

1974 report that introduced the compound: animal pharmacology per indexing terms, no abstract

Animal study

Hansl NR. Experientia. 1974;30(3):271-2. PMID 4824605.

Hansl, Experientia 1974;30(3):271 to 272, is titled A novel spasmolytic and CNS active agent and names the same compound. PubMed carries no abstract for this two-page paper. Its indexing terms (animals, rats, dogs, learning, avoidance learning, motor activity, blood pressure, heart rate, seizures, apomorphine, methamphetamine, parasympatholytics) indicate animal pharmacology, but no dose, effect size or toxicity figure can be taken from the record.

Participants / model
Rats and dogs per PubMed indexing terms; abstract not available
Treatment
not stated in the source
Follow-up
not stated in the source
Study design
Original preclinical report, no abstract
Funding
not stated in the source

The paper itself was not reviewed. Only the PubMed record and its indexing terms were used.

Read the original source
The one human study, 1978: slightly better acquisition, better retention of verbal information; size and design not stated

Human study

Hansl NR et al. Psychopharmacology (Berl). 1978;56(3):249-53. PMID 418433.

Hansl and Mead, Psychopharmacology 1978;56(3):249 to 253, studied the effect of PRL-8-53 on learning and on retention of verbal information in human subjects. Using the serial anticipation method under double-blind conditions, PRL-8-53 caused slight improvement of acquisition. Retention of verbal information improved to a statistically significant degree (most P values better than 0.01, some better than 0.001). Visual reaction time and motor control showed no significant change against placebo. The title says the doses were low and oral. The abstract does not give the number of subjects, the dose, the number of sessions, the age or sex of participants, whether the design was crossover or parallel, the retention interval, or whether dosing was single or repeated.

Participants / model
Human subjects, number not stated in the abstract
Treatment
Oral, low doses per the title; hydrochloride
Follow-up
not stated in the source
Study design
Original controlled study, abstract only; double-blind and placebo-compared per the abstract
Funding
not stated in the source

PubMed indexes the paper under the publication types randomized controlled trial, controlled clinical trial and clinical trial, which are indexing labels and not a description of the design. The full text is behind a paywall and was not reviewed, so size and design beyond double-blind, placebo-compared, serial anticipation are not established. The P values are not an effect size.

Read the original source
PubMed, 10 October 2026: 1 record for PRL-8-53, no replication, no registered study

PubMed search record

PubMed searches run on 10 October 2026 for PRL-8-53 and its spelling variants, for Hansl as author, and for learning and retention studies in humans in 1978, with a ClinicalTrials.gov search.

PRL-8-53 returned 1 record, the 1978 human paper, and so did PRL 8-53; PRL8-53 returned 0; the combined variants PRL-8-53, PRL 8-53, PRL8-53 and PRL-853 returned 1. A search for Hansl NR as author returned 3 records: the 1974 and 1978 PRL-8-53 papers and a 1977 Clinical Toxicology paper on papaverine and isoproterenol in dog vessels and rabbit intestine, which is unrelated. A search for nootropic or psychotropic with learning, retention, humans, oral and the year 1978 returned only the 1978 paper. ClinicalTrials.gov returned 0 studies for PRL-8-53. In the records reviewed, no second human study, replication, dose-response study, pharmacokinetic study or single-dose test exists, and no study confirms the effect in people other than its originator's group.

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 is known about the safety of PRL-8-53?

Unknown. The one human study's abstract gives no number of subjects, dose, schedule or adverse events, and no pharmacokinetic, toxicity or adverse-event report is retrievable, so safety and tolerability are undocumented.

The 1978 abstract does not report adverse events, the number of subjects, the dose or whether dosing was single or repeated, so no human safety or tolerability information can be stated. No pharmacokinetic study, toxicity figure or adverse-event report is retrievable from the records reviewed, and the 1974 animal report has no abstract.

Any figure for PRL-8-53 has to name the form it refers to. The hydrochloride studied in the 1978 paper (molecular weight 319.8) and the free base (283.4) are separate records.

For athletes, the WADA 2026 list does not name PRL-8-53, and no source reviewed says WADA has applied its general category for unapproved substances to it.

The one human study, 1978: slightly better acquisition, better retention of verbal information; size and design not stated

Human study

Hansl NR et al. Psychopharmacology (Berl). 1978;56(3):249-53. PMID 418433.

Hansl and Mead, Psychopharmacology 1978;56(3):249 to 253, studied the effect of PRL-8-53 on learning and on retention of verbal information in human subjects. Using the serial anticipation method under double-blind conditions, PRL-8-53 caused slight improvement of acquisition. Retention of verbal information improved to a statistically significant degree (most P values better than 0.01, some better than 0.001). Visual reaction time and motor control showed no significant change against placebo. The title says the doses were low and oral. The abstract does not give the number of subjects, the dose, the number of sessions, the age or sex of participants, whether the design was crossover or parallel, the retention interval, or whether dosing was single or repeated.

Participants / model
Human subjects, number not stated in the abstract
Treatment
Oral, low doses per the title; hydrochloride
Follow-up
not stated in the source
Study design
Original controlled study, abstract only; double-blind and placebo-compared per the abstract
Funding
not stated in the source

PubMed indexes the paper under the publication types randomized controlled trial, controlled clinical trial and clinical trial, which are indexing labels and not a description of the design. The full text is behind a paywall and was not reviewed, so size and design beyond double-blind, placebo-compared, serial anticipation are not established. The P values are not an effect size.

Read the original source
1974 report that introduced the compound: animal pharmacology per indexing terms, no abstract

Animal study

Hansl NR. Experientia. 1974;30(3):271-2. PMID 4824605.

Hansl, Experientia 1974;30(3):271 to 272, is titled A novel spasmolytic and CNS active agent and names the same compound. PubMed carries no abstract for this two-page paper. Its indexing terms (animals, rats, dogs, learning, avoidance learning, motor activity, blood pressure, heart rate, seizures, apomorphine, methamphetamine, parasympatholytics) indicate animal pharmacology, but no dose, effect size or toxicity figure can be taken from the record.

Participants / model
Rats and dogs per PubMed indexing terms; abstract not available
Treatment
not stated in the source
Follow-up
not stated in the source
Study design
Original preclinical report, no abstract
Funding
not stated in the source

The paper itself was not reviewed. Only the PubMed record and its indexing terms were used.

Read the original source
PubChem records: hydrochloride 319.8, free base 283.4, two separate compounds

Chemical identity record

PubChem, National Library of Medicine. Compound summary for CID 70700868, PRL-8-53 hydrochloride; the free base is CID 39989.

PRL-8-53 is methyl 3-[2-[benzyl(methyl)amino]ethyl]benzoate, studied as the hydrochloride. PubChem CID 70700868 is the hydrochloride: C18H22ClNO2, molecular weight 319.8, CAS 51352-87-5 (a CAS-format synonym), with the synonym PRL-8-53 (hydrochloride). The free base is a separate record, CID 39989: C18H21NO2, molecular weight 283.4, CAS 51352-88-6, listed as PRL-8-53 free base. The 1978 human paper names the compound as 3-(2-benzylmethylaminoethyl) benzoic acid methyl ester hydrochloride. The salt weighs 36.4 mass units more than the base (319.8 minus 283.4), so any dose figure depends on which form it refers to.

Participants / model
Chemical identity, not a clinical population
Treatment
Defined molecule; hydrochloride salt and free base are separate records
Follow-up
Not applicable
Study design
Chemical database record
Funding
not stated in the source

Identity and salt form only. It gives no pharmacology, dose or safety information.

Read the original source
WADA 2026 list does not name PRL-8-53; no US approval, scheduling or enforcement record

Regulatory record

World Anti-Doping Agency. The 2026 Prohibited List, in effect from 1 January 2026. 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. Searches run on 10 October 2026.

The WADA 2026 Prohibited List does not name PRL-8-53. S0 prohibits at all times any pharmacological substance not addressed elsewhere on the List and with no current approval for human therapeutic use, but no source reviewed says WADA has applied it to this compound. openFDA Drugs@FDA queries by substance, generic and brand name returned no match on 10 October 2026, a DailyMed search returned 0 labels, 21 CFR Part 1308 (eCFR version of 6 October 2026) does not name it, and FDA's Health Fraud Product Database (2,213 entries, current as of 5 October 2026) has no entry naming it. No approval, scheduling or enforcement record was found, and no toxicity or adverse-event report is retrievable from the records reviewed.

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.

Read the original source
PubMed, 10 October 2026: 1 record for PRL-8-53, no replication, no registered study

PubMed search record

PubMed searches run on 10 October 2026 for PRL-8-53 and its spelling variants, for Hansl as author, and for learning and retention studies in humans in 1978, with a ClinicalTrials.gov search.

PRL-8-53 returned 1 record, the 1978 human paper, and so did PRL 8-53; PRL8-53 returned 0; the combined variants PRL-8-53, PRL 8-53, PRL8-53 and PRL-853 returned 1. A search for Hansl NR as author returned 3 records: the 1974 and 1978 PRL-8-53 papers and a 1977 Clinical Toxicology paper on papaverine and isoproterenol in dog vessels and rabbit intestine, which is unrelated. A search for nootropic or psychotropic with learning, retention, humans, oral and the year 1978 returned only the 1978 paper. ClinicalTrials.gov returned 0 studies for PRL-8-53. In the records reviewed, no second human study, replication, dose-response study, pharmacokinetic study or single-dose test exists, and no study confirms the effect in people other than its originator's group.

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 does PRL-8-53 sit in D tier?

There is one published human study, double-blind and placebo-compared per its abstract and co-authored by the originator in 1978, plus an abstractless 1974 animal report, and nothing since. The number of subjects and the design are unknown, the result was never replicated, and safety and pharmacokinetics are undocumented.

The result rests on an unknown number of subjects, comes from the group that first described the compound, and was never replicated in the indexed record. Safety and pharmacokinetics are undocumented, so the claims outrun the data.

D rather than F because some human data exist. The supplier's claim is supported only in part: improved retention of verbal information after low oral doses, with no statement that the effect is acute.

The one human study, 1978: slightly better acquisition, better retention of verbal information; size and design not stated

Human study

Hansl NR et al. Psychopharmacology (Berl). 1978;56(3):249-53. PMID 418433.

Hansl and Mead, Psychopharmacology 1978;56(3):249 to 253, studied the effect of PRL-8-53 on learning and on retention of verbal information in human subjects. Using the serial anticipation method under double-blind conditions, PRL-8-53 caused slight improvement of acquisition. Retention of verbal information improved to a statistically significant degree (most P values better than 0.01, some better than 0.001). Visual reaction time and motor control showed no significant change against placebo. The title says the doses were low and oral. The abstract does not give the number of subjects, the dose, the number of sessions, the age or sex of participants, whether the design was crossover or parallel, the retention interval, or whether dosing was single or repeated.

Participants / model
Human subjects, number not stated in the abstract
Treatment
Oral, low doses per the title; hydrochloride
Follow-up
not stated in the source
Study design
Original controlled study, abstract only; double-blind and placebo-compared per the abstract
Funding
not stated in the source

PubMed indexes the paper under the publication types randomized controlled trial, controlled clinical trial and clinical trial, which are indexing labels and not a description of the design. The full text is behind a paywall and was not reviewed, so size and design beyond double-blind, placebo-compared, serial anticipation are not established. The P values are not an effect size.

Read the original source
Publisher page: the 1978 co-author is the compound's originator, at Creighton University

Human study

Hansl NR, Mead BT. Psychopharmacology. 1978;56(3):249-253. Springer article page, doi 10.1007/BF00432846.

Springer's page for the 1978 paper lists the authors, Nikolaus R. Hansl and Beverley T. Mead, at the Department of Medicinal Chemistry and the Department of Psychiatry, Creighton University, Omaha, Nebraska. Hansl is also the sole author of the 1974 report that introduced the compound, whose Springer page lists Creighton University and Pacific Research Laboratories, Santa Barbara, California. So the person who first described the compound co-authored the only human study. PubMed's own record for the 1978 paper carries no affiliation. No independent human study was found.

Participants / model
Not a clinical population
Treatment
Not applicable
Follow-up
Not applicable
Study design
Journal publisher page (authorship and affiliations)
Funding
not stated in the source

Affiliations were read from the publisher pages and not confirmed against the printed paper.

Read the original source
PubMed, 10 October 2026: 1 record for PRL-8-53, no replication, no registered study

PubMed search record

PubMed searches run on 10 October 2026 for PRL-8-53 and its spelling variants, for Hansl as author, and for learning and retention studies in humans in 1978, with a ClinicalTrials.gov search.

PRL-8-53 returned 1 record, the 1978 human paper, and so did PRL 8-53; PRL8-53 returned 0; the combined variants PRL-8-53, PRL 8-53, PRL8-53 and PRL-853 returned 1. A search for Hansl NR as author returned 3 records: the 1974 and 1978 PRL-8-53 papers and a 1977 Clinical Toxicology paper on papaverine and isoproterenol in dog vessels and rabbit intestine, which is unrelated. A search for nootropic or psychotropic with learning, retention, humans, oral and the year 1978 returned only the 1978 paper. ClinicalTrials.gov returned 0 studies for PRL-8-53. In the records reviewed, no second human study, replication, dose-response study, pharmacokinetic study or single-dose test exists, and no study confirms the effect in people other than its originator's group.

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 records: hydrochloride 319.8, free base 283.4, two separate compounds

Chemical identity record

PubChem, National Library of Medicine. Compound summary for CID 70700868, PRL-8-53 hydrochloride; the free base is CID 39989.

PRL-8-53 is methyl 3-[2-[benzyl(methyl)amino]ethyl]benzoate, studied as the hydrochloride. PubChem CID 70700868 is the hydrochloride: C18H22ClNO2, molecular weight 319.8, CAS 51352-87-5 (a CAS-format synonym), with the synonym PRL-8-53 (hydrochloride). The free base is a separate record, CID 39989: C18H21NO2, molecular weight 283.4, CAS 51352-88-6, listed as PRL-8-53 free base. The 1978 human paper names the compound as 3-(2-benzylmethylaminoethyl) benzoic acid methyl ester hydrochloride. The salt weighs 36.4 mass units more than the base (319.8 minus 283.4), so any dose figure depends on which form it refers to.

Participants / model
Chemical identity, not a clinical population
Treatment
Defined molecule; hydrochloride salt and free base are separate records
Follow-up
Not applicable
Study design
Chemical database record
Funding
not stated in the source

Identity and salt form only. It gives no pharmacology, dose or safety information.

Read the original source
The one human study, 1978: slightly better acquisition, better retention of verbal information; size and design not stated

Human study

Hansl NR et al. Psychopharmacology (Berl). 1978;56(3):249-53. PMID 418433.

Hansl and Mead, Psychopharmacology 1978;56(3):249 to 253, studied the effect of PRL-8-53 on learning and on retention of verbal information in human subjects. Using the serial anticipation method under double-blind conditions, PRL-8-53 caused slight improvement of acquisition. Retention of verbal information improved to a statistically significant degree (most P values better than 0.01, some better than 0.001). Visual reaction time and motor control showed no significant change against placebo. The title says the doses were low and oral. The abstract does not give the number of subjects, the dose, the number of sessions, the age or sex of participants, whether the design was crossover or parallel, the retention interval, or whether dosing was single or repeated.

Participants / model
Human subjects, number not stated in the abstract
Treatment
Oral, low doses per the title; hydrochloride
Follow-up
not stated in the source
Study design
Original controlled study, abstract only; double-blind and placebo-compared per the abstract
Funding
not stated in the source

PubMed indexes the paper under the publication types randomized controlled trial, controlled clinical trial and clinical trial, which are indexing labels and not a description of the design. The full text is behind a paywall and was not reviewed, so size and design beyond double-blind, placebo-compared, serial anticipation are not established. The P values are not an effect size.

Read the original source
Publisher page: the 1978 co-author is the compound's originator, at Creighton University

Human study

Hansl NR, Mead BT. Psychopharmacology. 1978;56(3):249-253. Springer article page, doi 10.1007/BF00432846.

Springer's page for the 1978 paper lists the authors, Nikolaus R. Hansl and Beverley T. Mead, at the Department of Medicinal Chemistry and the Department of Psychiatry, Creighton University, Omaha, Nebraska. Hansl is also the sole author of the 1974 report that introduced the compound, whose Springer page lists Creighton University and Pacific Research Laboratories, Santa Barbara, California. So the person who first described the compound co-authored the only human study. PubMed's own record for the 1978 paper carries no affiliation. No independent human study was found.

Participants / model
Not a clinical population
Treatment
Not applicable
Follow-up
Not applicable
Study design
Journal publisher page (authorship and affiliations)
Funding
not stated in the source

Affiliations were read from the publisher pages and not confirmed against the printed paper.

Read the original source
1974 report that introduced the compound: animal pharmacology per indexing terms, no abstract

Animal study

Hansl NR. Experientia. 1974;30(3):271-2. PMID 4824605.

Hansl, Experientia 1974;30(3):271 to 272, is titled A novel spasmolytic and CNS active agent and names the same compound. PubMed carries no abstract for this two-page paper. Its indexing terms (animals, rats, dogs, learning, avoidance learning, motor activity, blood pressure, heart rate, seizures, apomorphine, methamphetamine, parasympatholytics) indicate animal pharmacology, but no dose, effect size or toxicity figure can be taken from the record.

Participants / model
Rats and dogs per PubMed indexing terms; abstract not available
Treatment
not stated in the source
Follow-up
not stated in the source
Study design
Original preclinical report, no abstract
Funding
not stated in the source

The paper itself was not reviewed. Only the PubMed record and its indexing terms were used.

Read the original source
WADA 2026 list does not name PRL-8-53; no US approval, scheduling or enforcement record

Regulatory record

World Anti-Doping Agency. The 2026 Prohibited List, in effect from 1 January 2026. 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. Searches run on 10 October 2026.

The WADA 2026 Prohibited List does not name PRL-8-53. S0 prohibits at all times any pharmacological substance not addressed elsewhere on the List and with no current approval for human therapeutic use, but no source reviewed says WADA has applied it to this compound. openFDA Drugs@FDA queries by substance, generic and brand name returned no match on 10 October 2026, a DailyMed search returned 0 labels, 21 CFR Part 1308 (eCFR version of 6 October 2026) does not name it, and FDA's Health Fraud Product Database (2,213 entries, current as of 5 October 2026) has no entry naming it. No approval, scheduling or enforcement record was found, and no toxicity or adverse-event report is retrievable from the records reviewed.

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.

Read the original source
PubMed, 10 October 2026: 1 record for PRL-8-53, no replication, no registered study

PubMed search record

PubMed searches run on 10 October 2026 for PRL-8-53 and its spelling variants, for Hansl as author, and for learning and retention studies in humans in 1978, with a ClinicalTrials.gov search.

PRL-8-53 returned 1 record, the 1978 human paper, and so did PRL 8-53; PRL8-53 returned 0; the combined variants PRL-8-53, PRL 8-53, PRL8-53 and PRL-853 returned 1. A search for Hansl NR as author returned 3 records: the 1974 and 1978 PRL-8-53 papers and a 1977 Clinical Toxicology paper on papaverine and isoproterenol in dog vessels and rabbit intestine, which is unrelated. A search for nootropic or psychotropic with learning, retention, humans, oral and the year 1978 returned only the 1978 paper. ClinicalTrials.gov returned 0 studies for PRL-8-53. In the records reviewed, no second human study, replication, dose-response study, pharmacokinetic study or single-dose test exists, and no study confirms the effect in people other than its originator's group.

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 PRL-8-53 in D tier?

D fits one published human study with open questions: double-blind and placebo-compared per its abstract, from the originator's group, with unknown size and no replication. Safety and pharmacokinetics are undocumented, and some human data exist, which keeps it above F.