Phenylpiracetam (Fonturacetam)

Identity, and one molecule under six names

The names are the complication here, not the chemistry. PubChem holds one record, filed under phenylpiracetam: CID 132441, CAS 77472-70-9, formula C12H14N2O2, molecular weight 218.25, InChIKey LYONXVJRBWWGQO-UHFFFAOYSA-N, IUPAC name 2-(2-oxo-4-phenylpyrrolidin-1-yl)acetamide. The FDA Global Substance Registration System carries the same CAS and formula under the International Nonproprietary Name fonturacetam, UNII 99QW5JU66Y, INN code 9111, with carphedon, carphedone, 4-phenylpiracetam and phenotropyl parked on that one record as synonyms (the registry's spelling; the literature uses phenotropil). Six designations, one molecule. The registry is explicit that the substance is the racemate: among the systematic names it carries is (R,S)-2-(2-oxo-4-phenylpyrrolidin-1-yl)acetamide.

Chirality is the first thing separating the literature from the drug. The pyrrolidinone ring carries a stereocentre at position four, and most mechanistic work published since 2011 was done on resolved enantiomers rather than on the racemate registered as a medicine. Dekundy and colleagues define MRZ-9547 as d-(2-(2-oxo-4(R)-phenylpyrrolidin-1-yl)-acetamide), which is R-phenylpiracetam, and Sommer and colleagues describe MRZ-9546 as its l-enantiomer. A result recorded for one enantiomer is not a result about the racemate, and the two did not behave alike in the single study that tested them side by side.

Regulatory position differs by jurisdiction and is unambiguous in each. In Russia the racemate is a registered prescription nootropic. In the United States it is not approved for human use: Cohen and colleagues selected products for analysis on the basis of four drugs unapproved in the United States, phenylpiracetam among them. A market-surveillance study by twelve official medicines control laboratories across Europe and Australia classified it among substances available on prescription in Russia and unauthorised in the participating territories, and recorded it being intercepted as bulk raw material rather than as finished product.

What the 1983 paper reported

Bobkov and colleagues described the compound in Biulleten Eksperimentalnoi Biologii i Meditsiny in 1983, comparing it against piracetam, morpholene and 4-phenylpyrrolidone. The indexed abstract records four positive findings: operant behaviour activated more powerfully than by piracetam, the psychodepressant effects of diazepam removed, post-rotational nystagmus inhibited, and the development of retrograde amnesia prevented. It records one dissociation from the parent compound, a specific anticonvulsant action that piracetam did not show. Species, route and group size appear nowhere in the abstract, so the experiments behind those statements cannot be reconstructed from the indexed record.

The fifth finding is the one that does not travel. In the same abstract, high doses produced psychodepressant effects, the opposite direction from the activation reported at lower ones. Secondary summaries reliably carry the stimulant results and reliably omit the reversal. Read back to its first description, the compound's reputation begins with an unquantified dose-dependent contradiction, in a paper that publishes no dose, no species and no number of animals. Nothing indexed since has established which doses fall on which side of it.

Absent from the 1983 abstract is any mention of cold, hypothermia, endurance or exercise. The earliest indexed sentence connecting the molecule to those effects opens a 1999 method paper on urinary detection, which states that carphedon is effective in increasing physical endurance and cold resistance and cites nothing for it. That sentence is a chromatographer's preamble, not a result. Pairing any of the four names with hypothermia, cold or thermoregulation in PubMed returns that same paper and nothing else.

The transporter work, and which molecule it was done on

Zvejniece and colleagues compared the racemate and both resolved enantiomers in mice in 2011. In the open field, locomotor activity rose after a single administration of the R-enantiomer at 10 and 50 mg/kg and of the S-enantiomer at 50 mg/kg. In the forced swim test the R-enantiomer was active at 50 and 100 mg/kg, the S-enantiomer at 100 mg/kg. In passive avoidance only the R-enantiomer altered performance, at 1 mg/kg. Brain tissue concentrations measured by liquid chromatography-tandem mass spectrometry were similar for both enantiomers, which removes differential brain penetration as an explanation. The indexed abstract states no group size, no route, and no separate figure for the racemate arm.

Six years later the same laboratory reported the S-enantiomer in two obesity models: mice on a Western diet for eight weeks and obese Zucker rats for twelve, dosed perorally. Body weight gain and fat mass increase fell in both, plasma glucose and leptin fell, and locomotor activity in the open field did not change. That paper's title asserts selective dopamine transporter inhibition and its abstract attributes the finding to earlier work, but its reference list contains no primary radioligand paper for the S-enantiomer. The assertion arrives in the title before it arrives in the record.

Target profiling by radioligand binding and enzymatic assay was published for the R-enantiomer in 2020, and the dopamine transporter was the only significant target it returned. That paper is also the only source of a quantified pharmacokinetic parameter located under any of the four names: after 50 mg/kg in male mice the compound reached brain tissue within 15 minutes by both intraperitoneal and peroral routes, at maximal brain concentrations of 28 and 18 micrograms per gram respectively. Zvejniece 2011 also measured brain-tissue concentrations by UPLC-MS/MS after a single administration, but its indexed abstract reports only that the two enantiomers were similar, with no concentration, no timepoint and no route (PMID 21689376). In that same 2020 experiment in male mice, a single intraperitoneal injection was followed by attenuation of the lipopolysaccharide-induced body-temperature drop and of brain TNF-alpha, IL-1beta and iNOS overexpression (PMID 32279140).

Work on the R-enantiomer under its industrial code ran in parallel. Sommer and colleagues reported that MRZ-9547 is a selective dopamine transporter inhibitor that moderately stimulated striatal dopamine release in rats, and that it raised responding on a progressive ratio schedule more than methylphenidate, modafinil or d-amphetamine did in the same tasks. Dekundy and colleagues reported dose-dependent effects at 25 to 100 mg/kg intraperitoneally in haloperidol-treated and 6-hydroxydopamine-lesioned rats, with no significant effect on abnormal involuntary movements. A phase 1 study in healthy subjects appears in Huot's 2015 review as a 2014 conference abstract; no full publication is indexed.

Receptor claims the binding assays did not support

Firstova and colleagues ran radioligand binding on rat brain membranes across eight nootropic drugs in 2011. Nooglutil competed with an AMPA receptor agonist at an IC50 of 6.4 micromolar, noopept at 80 micromolar, semax at metabotropic glutamate sites at 33 micromolar and dimebon at the NMDA channel at 59 micromolar. Piracetam and phenotropil, tested from 10 to the minus four down to 10 to the minus ten molar, did not affect binding to any glutamate receptor examined. That is a negative result from a direct measurement, published by a laboratory that found positive results for other compounds in the same run.

Receptor-density claims for this compound appear to have been imported from a different molecule. Kovalev and colleagues in 2008 measured NMDA and nicotinic binding sites in mice separated by exploratory efficacy, and reported that piracetam raised NMDA binding sites by 70 per cent in the low-efficacy animals and lowered neocortical nicotinic receptor density by 55 and 40 per cent in the two subpopulations. Phenylpiracetam was not among the drugs tested. The circulating statement that it increases the density of NMDA, GABA-A, nicotinic and dopamine receptors has no counterpart experiment indexed under any of its four names.

One neurotrophin measurement exists. Firstova and colleagues in 2009 gave six nootropic drugs subchronically to mice divided by exploratory efficacy and measured BDNF by region. Hippocampal BDNF rose in the low-efficacy animals only, from 0.091 to 0.119 picograms per microgram for phenotropil, against 0.115 for piracetam and 0.123 for semax. Cortical BDNF rose after piracetam and semax but not after phenotropil, and nothing changed in the high-efficacy animals. Direction of effect depended on region and on baseline, and the effect was absent where there was no baseline deficit.

The human record, and what its indexing does not match

Counts first. A PubMed search across phenotropil, phenylpiracetam, carphedon and fonturacetam returns 50 records as of 18 August 2026. Six carry the publication type Clinical Trial, four of those Controlled Clinical Trial. One carries Randomized Controlled Trial. One carries Systematic Review and Meta-Analysis. A publication-type query for Retracted Publication, Retraction of Publication and Expression of Concern across the whole corpus returns nothing. ClinicalTrials.gov queries on phenylpiracetam, carphedon, fonturacetam, phenotropil, 4-phenylpiracetam and MRZ-9547 each returned totalCount zero, so no study of this molecule or either enantiomer has been prospectively registered where that registry indexes.

Typing and abstracts do not line up. Savenkov and colleagues, the one paper PubMed types as a randomised controlled trial, examined 75 patients with symptomatic focal post-traumatic epilepsy and describes neither randomisation, nor blinding, nor allocation, nor a placebo arm in its indexed abstract, which closes by recommending the drug. Grebeniuk and colleagues describe what that paper does not: a double-blind, placebo-controlled, randomised comparison in 90 adults given 100 or 200 mg as add-on to standard antiepileptic drugs. PubMed types it as neither. Its abstract publishes no effect size, no p-value and no arm sizes, and records that in 40 per cent of patients the drug did not reduce the negative effects of the background regimen.

Largest datasets, weakest designs. Koval'chuk and colleagues followed 400 patients after ischaemic stroke, 200 given three courses at 400 mg daily across the year after the event, and reported better recovery on the Barthel, Lindmark, Scandinavian and Merton and Sutton scales at p less than 0.0001; the abstract describes no randomisation and no blinding. Fedin and colleagues reported the TRIUMPH programme, 1170 patients aged 45 to 65 with chronic brain ischaemia treated at 100 mg for two and three months, with MFI-20 asthenia scores more than halved at three months. TRIUMPH is titled a non-interventional observational programme and had no control group.

Devlikamova and Safina pooled eleven articles and 549 patients in 2025, all at 200 mg daily, reporting a mean MFI-20 reduction of 16.3 points at day 30, a 95 per cent confidence interval from 8.85 to 23.85, and adverse events at 5.5 per cent. What the abstract describes is a pooled within-group change from baseline. It names no placebo comparison, reports no control arm and gives no pooled between-group difference. The included studies are Russian-language, and the pooling appeared in the journal that published most of them. Medvedev and colleagues, comparing two drugs over twelve weeks with 35 patients per arm, recorded the anxiolytic effect diminishing after four to eight weeks.

Doping status, and what analysis of products has found

Jedrejko and colleagues open their 2023 review with a date: fonturacetam was the first nootropic prohibited in sport, in 1998. Pokrywka and colleagues, surveying a national supplement market in 2025, tabulate it under section S6.A of the World Anti-Doping Agency Prohibited List as phenylpiracetam, with fonturacetam and carphedon as the parenthetical names (PMID 41048238); the List's own entry text and its specified or non-specified designation were not retrievable this session and are not asserted here. The same paper then uses 4-phenylpiracetam as the structural comparator against which nine other substances of unclear status are assessed, seven of them racetams, the other two a dipeptide and a piperazine derivative. In anti-doping practice the molecule functions as the reference case for a whole chemical family.

Detection preceded most of the pharmacology. Kim and colleagues published a solid-phase microextraction assay for carphedon in human urine in 1999, with a detection limit of 0.01 micrograms per millilitre, and Strano Rossi and Botrè listed carphedon among the stimulants found across roughly 100,000 urine samples analysed by one national anti-doping laboratory between 2000 and 2009, without a separate count for it.

Two content-analysis studies measured what was in containers rather than what happened in people. Cohen and colleagues selected ten cognitive-enhancement products by searching supplement databases for labels declaring omberacetam, aniracetam, phenylpiracetam or oxiracetam. Omberacetam and aniracetam were detected; phenylpiracetam was not detected in any of the ten, while phenibut, vinpocetine and picamilon, declared on no label, were. Nine of twelve checkable declared quantities were inaccurate. The twelve-laboratory survey documented 159 samples between 2020 and 2024, 69 per cent from the illegal market, and recorded phenylpiracetam among substances intercepted as bulk raw material.

A 2020 review of cognitive enhancers circulating in online drug-user communities put the pharmacology more bluntly than anything above. Having identified phenylpiracetam among the racetams discussed in those forums, Napoletano and colleagues wrote that there are no available studies on coluracetam, fasoracetam and phenylpiracetam. As a description of the indexed corpus that is too strong; 50 records exist. As a description of the English-language human corpus it is accurate, because that corpus is empty.

What is not known

No study of this molecule has been prospectively registered where ClinicalTrials.gov indexes: that registry returns zero results for phenylpiracetam, carphedon, fonturacetam, phenotropil, 4-phenylpiracetam and MRZ-9547 alike, and no other national or regional registry was queried this session. No pharmacokinetic parameter for people has been located in a retrievable primary report, so there is no half-life, no bioavailability figure, no clearance value and no metabolite identification; the one phase 1 study in healthy subjects known to have run exists only as a 2014 conference abstract cited inside a review, with no indexed publication and no registry record. The human literature is entirely Russian-language, and the single indexed abstract describing a double-blind placebo-controlled randomised design publishes no effect size, no p-value and no arm sizes. Zvejniece 2011 tested the racemate alongside both resolved enantiomers in the same mouse battery (PMID 21689376), but its indexed abstract publishes the dose-response results only for the R- and S-enantiomers and reports no racemate figure, so the proportion of the registered medicine's activity attributable to the R-enantiomer cannot be read off the indexed record, and the S-enantiomer's characterisation as a selective transporter inhibitor rests on an assertion rather than a located radioligand paper. Longest human observation retrievable is a year of intermittent treatment courses after stroke and three months of continuous assessment in an uncontrolled observational programme; the only published observation resembling tolerance is one comparative study recording an anxiolytic effect diminishing after four to eight weeks. No indexed study addresses use in people under 18, in pregnancy or on discontinuation, and no chronic toxicology study in any species was located under any of the four names. The compound is not approved for human use in the United States or the European Union, and material circulating outside Russian pharmacy supply has been intercepted as unregulated bulk raw material.

Questions