Phenylpiracetam

Phenylpiracetam, also known as fonturacetam (INNTooltip International nonproprietary name) and sold under the brand names Phenotropil, Actitropil, and Carphedon among others, is a stimulant and nootropic medication used in Russia and certain other Eastern European countries in the treatment of cerebrovascular deficiency, depression, apathy, and attention, and memory problems, among other indications.^[2][4][1][3] It is also used in Russian cosmonauts to improve physical, mental, and cognitive abilities.^[2][1] The drug is taken by mouth.^[2]

Phenylpiracetam

Clinical data
Trade names	Phenotropil, Fenotropil, Phenotropyl, Fenotropyl, Carphedon, Actitropil
Other names	Fonturacetam; Phenotropil; Fenotropil; 4-Phenylpiracetam; PP[1]
Pregnancy category	Unknown
Routes of administration	Oral (tablets)[2][3]
Drug class	Atypical dopamine reuptake inhibitor[4]
ATC code	None
Legal status
Legal status	AU: S4 (Prescription only) US: Unapproved "New Drug" (as defined by 21 U.S. Code § 321(p)(1)). Use in dietary supplements, food, or medicine is unlawful; otherwise uncontrolled. RU: Rx-only
Pharmacokinetic data
Bioavailability	~100%[2][3]
Metabolism	Not metabolized[3]
Onset of action	<1 hour[3][2]
Elimination half-life	3–5 hours[2][3]
Excretion	Urine: ~40%[3] Bile, sweat: ~60%[3]
Identifiers
IUPAC name (R,S)-2-(2-oxo-4-phenylpyrrolidin-1-yl)acetamide
CAS Number	77472-70-9 Y
PubChem CID	132441
ChemSpider	116950 Y
UNII	99QW5JU66Y
CompTox Dashboard (EPA)	DTXSID30868438
ECHA InfoCard	100.214.874
Chemical and physical data
Formula	C12H14N2O2
Molar mass	218.256 g·mol−1
3D model (JSmol)	Interactive image
Chirality	Racemic mixture
Boiling point	486.4 °C (907.5 °F)
SMILES C1=CC=CC=C1C2CN(C(C2)=O)CC(=O)N
InChI InChI=1S/C12H14N2O2/c13-11(15)8-14-7-10(6-12(14)16)9-4-2-1-3-5-9/h1-5,10H,6-8H2,(H2,13,15) N Key:LYONXVJRBWWGQO-UHFFFAOYSA-N N
(verify)

Side effects of phenylpiracetam include sleep disturbances among others.^[2] The mechanism of action of phenylpiracetam was originally unknown.^[2][4][5] However, it was discovered that (R)-phenylpiracetam is a selective atypical dopamine reuptake inhibitor in 2014.^[4][6] In addition, phenylpiracetam interacts with certain nicotinic acetylcholine receptors.^[5] Chemically, phenylpiracetam is a racetam and phenethylamine and is structurally related to piracetam.^[2][7]

Phenylpiracetam was first described by 1983.^[8] It was approved for medical use in Russia in 2003.^[2] Development of (R)-phenylpiracetam (code name MRZ-9547) in the West as a potential treatment for fatigue related to Parkinson's disease began by 2014.^[9][6]

Medical uses

Phenylpiracetam is used in the treatment of a variety of different medical conditions.^[2][1][3] It is specifically approved in Russia for treatment of cerebrovascular deficiency, depression, apathy, attention deficits, and memory decline.^[2][1][3] It is used to improve symptoms following encephalopathy, brain injury, and glioma surgery.^[2][1][3] The drug has been reported to improve symptoms of depression, anxiety, asthenia, and fatigue, as well as to improve cognitive performance and memory.^[2][1][3] It also has anticonvulsant effects and has been used as an add-on therapy in epilepsy.^[2][1]

Phenylpiracetam is typically prescribed as a general stimulant or to increase tolerance to extreme temperatures and stress.^[10]

Clinical use of phenylpiracetam has shown to be more potent than piracetam and is used for a wider-range of indications.^[2]

A few small clinical studies have shown possible links between prescription of phenylpiracetam and improvement in a number of encephalopathic conditions, including lesions of cerebral blood pathways, traumatic brain injury and certain types of glioma.^[11]

Clinical trials were conducted at the Serbsky State Scientific Center for Social and Forensic Psychiatry. The Serbsky Center, Moscow Institute of Psychiatry, and Russian Center of Vegetative Pathology are reported to have confirmed the effectiveness of phenylpiracetam describing the following effects: improvement of regional blood flow in ischemic regions of the brain, reduction of depressive and anxiety disorders, increase the resistance of brain tissue to hypoxia and toxic effects, improving concentration and mental activity, a psycho-activating effect, increase in the threshold of pain sensitivity, improvement in the quality of sleep, and an anticonvulsant action,^[12] though with the side effect of an anorexic effect in extended use.^[13][14]

Available forms

Phenylpiracetam is available in the form of 100 mg oral tablets.^[15][3]

Contraindications

Phenylpiracetam has a number of contraindications, such as individual intolerance.^[3]

Side effects

Side effects of phenylpiracetam include insomnia or sleep disturbances, psychomotor agitation, flushing, a feeling of warmth, and increased blood pressure, among others.^[2][3]

Overdoses

Overdose has not been reported.^[3]

Pharmacology

Pharmacodynamics

Phenylpiracetam is a racetam and is described as a stimulant.^[2][4][1][3] Racetams have a variety of different pharmacological activities and have varying effects.^{[16][17][7][18][2]} For example, phenylpiracetam is a stimulant, piracetam is a nootropic, and levetiracetam is an anticonvulsant.^[16] The mechanisms of action of most racetams, with some exceptions, are unknown.^[17][7][18]

Phenylpiracetam is a racemic mixture.^[4] (R)-Phenylpiracetam is the most active enantiomer and is much more potent in stimulating locomotor activity than (S)-phenylpiracetam, which is ineffective.^[4][19] However, (S)-phenylpiracetam retains some activity in most pharmacological tests.^[4] On the other hand, in one animal test, the passive avoidance test, (S)-phenylpiracetam appeared to be antagonistic of (R)-phenylpiracetam.^[4]

Dopamine reuptake inhibitor

Experiments performed on Sprague-Dawley rats in a European patent for using phenylpiracetam to treat sleep disorders showed an increase in extracellular dopamine levels after administration. The patent asserts discovery of phenylpiracetam's action as a dopamine reuptake inhibitor^[20] as its basis.^[21]

The peculiarity of this invention compared to former treatment approaches for treating sleep disorders is the so far unknown therapeutic efficacy of (R)-phenylpiracetam, which is presumably based at least in part on the newly identified activity of (R)-phenylpiracetam as the dopamine re-uptake inhibitor

Both enantiomers of phenylpiracetam, (R)-phenylpiracetam and (S)-phenylpiracetam, have been described in peer-reviewed research as dopamine transporter (DAT) inhibitors in rodents, confirming the patent claim.^[22][23][19] Their actions at the norepinephrine transporter (NET) vary: (R)-phenylpiracetam acts as a dual norepinephrine–dopamine reuptake inhibitor (NDRI), with 11-fold lower affinity for the NET than for the DAT, whereas the (S)-enantiomer is selective for the DAT.^[19] However, whereas (R)-phenylpiracetam stimulates locomotor activity, (S)-phenylpiracetam does not do so.^[4][19] This variation in effects has also been seen with other dopamine reuptake inhibitors.^{[24][25][26][27]}

Other atypical dopamine reuptake inhibitors include modafinil,^[24][25] mesocarb (Sydnocarb),^[28][29][30] and solriamfetol.^[31]

Other actions

Phenylpiracetam binds to α₄β₂ nicotinic acetylcholine receptors in the mouse brain cortex with an IC₅₀Tooltip half-maximal inhibitory concentration of 5.86 μM.^[1][32][33]

Racetams generally, but including phenylpiracetam, have been described as AMPA receptor potentiators.^[34]

Animal studies

Research on animals has indicated that phenylpiracetam may have antiamnesic, antidepressant, anxiolytic, and anticonvulsant effects.^[2][35]

Phenylpiracetam has been shown to reverse the sedative or depressant effects of the benzodiazepine diazepam, increases operant behavior, inhibits post-rotational nystagmus, prevents retrograde amnesia, and has anticonvulsant properties in animal models.^{[2][5][32][8][36]}

In Wistar rats with gravitational cerebral ischemia, phenylpiracetam reduced the extent of neuralgic deficiency manifestations, retained the locomotor, research, and memory functions, increased the survival rate, and lead to the favoring of local cerebral flow restoration upon the occlusion of carotid arteries to a greater extent than did piracetam.^[37]

In tests against a control, Sprague-Dawley rats given free access to less-preferred rat chow and trained to operate a lever repeatedly to obtain preferred rat chow performed additional work when given methylphenidate, dextroamphetamine, and phenylpiracetam.^[20] Rats administered 100 mg/kg phenylpiracetam performed, on average, 375% more work than rats given placebo, and consumed little non-preferred rat chow.^[20] In comparison, rats administered 1mg/kg dextroamphetamine or 10 mg/kg methylphenidate performed, on average, 150% and 170% more work respectively, and consumed half as much non-preferred rat chow.^[20]

Present data show that (R)-phenylpiracetam increases motivation, i.e., the work load, which animals are willing to perform to obtain more rewarding food. At the same time consumption of freely available normal food does not increase. Generally this indicates that (R)-phenylpiracetam increase motivation [...] The effect of (R)-phenylpiracetam is much stronger than that of methylphenidate and amphetamine.^[20]

Pharmacokinetics

The pharmacokinetics of phenylpiracetam in humans are unpublished.^[1] In any case, the drug is described as having an oral bioavailability of approximately 100%, as having an onset of action of less than 1 hour, as not being metabolized, as being excreted unchanged about 40% in urine and 60% in bile and sweat, and as having an elimination half-life of 3 to 5 hours.^[2][3] In rodents, its absorption occurs within 1 hour with oral administration or intramuscular injection and its elimination half-life is 2.5 to 3 hours.^[2]

Chemistry

Phenylpiracetam, also known as 4-phenylpiracetam, is a racetam (i.e., a 2-oxo-1-pyrrolidine acetamide derivative) and the 4-phenyl-substituted analogue of piracetam.^[2][8] In contrast to piracetam and most other racetams however, phenylpiracetam contains β-phenylethylamine within its chemical structure and hence can additionally be conceptualized as a substituted phenethylamine.^[38]

Phenylpiracetam is a racemic mixture of (R)- and (S)-enantiomers, (R)-phenylpiracetam (MRZ-9547) and (S)-phenylpiracetam.^{[38][4][6][19]}

Derivatives

RGPU-95 (4-chlorophenylpiracetam) is a derivative of phenylpiracetam described as having 5- to 10-fold greater potency.^[39][40] Cebaracetam (CGS-25248; ZY-15119) is a derivative of RGPU-95 in which the terminal amide has been replaced with a 2-piperazinone moiety.^[41]

Methylphenylpiracetam, including all four of its stereoisomers (especially the (4R,5S)-enantiomer E1R), is a positive allosteric modulator of the sigma σ₁ receptor.^[4][42][43] It is currently the only known racetam demonstrating σ₁ receptor modulation.^[4] Whereas phenylpiracetam stimulates locomotor activity in animals, the E1R enantiomer of methylphenylpiracetam does not do so at doses of up to 200 mg/kg.^[4][43]

Phenylpiracetam hydrazide is a hydrazide derivative of phenylpiracetam described as having anticonvulsant effects.^[7][44]

Other derivatives of phenylpiracetam have also been developed and studied.^[7]

History

Phenylpiracetam was first described in the scientific literature by 1983.^[8] It was developed in 1983 as a medication for Soviet cosmonauts to treat the prolonged stresses of working in space. Phenylpiracetam was created at the Russian Academy of Sciences Institute of Biomedical Problems in an effort led by psychopharmacologist Valentina Ivanovna Akhapkina (Валентина Ивановна Ахапкина).^[45][46] Subsequently, it became available as a prescription drug in Russia. It was approved in 2003 for treatment of various conditions.^[2]

Pilot-cosmonaut Aleksandr Serebrov described being issued and using phenylpiracetam, as well as it being included in the Soyuz spacecraft's standard emergency medical kit, during his 197-days working in space aboard the Mir space station. He reported "the drug acts as the equalizer of the whole organism, "tidying it up", completely excluding impulsiveness and irritability inevitable in the stressful conditions of space flight."^[45]

Society and culture

Availability

Phenotropil 100 mg from Russia.

While not prescribed as a pharmaceutical in the West, in Russia and certain other Eastern European countries it is available as a prescription medicine under brand names including Phenotropil (also spelled Fenotropil, Phenotropyl, and Fenotropyl), Actitropil, and Nanotropil, among others.

Phenylpiracetam is not scheduled by the United States Drug Enforcement Administration (DEA) as of 2016.^[47]

Manufacturer

Phenylpiracetam is manufactured by the pharmaceutical companies Valenta Pharm and Pharmstandard (Pharmstandart) in Russia.^[2][48][3]

Doping in sport

Phenylpiracetam has stimulant effects and may be used as a doping agent in sport.^[49][50] As a result, it is on the list of stimulants banned for in-competition use by the World Anti-Doping Agency (WADA).^[51][49] This list is applicable in all Olympic sports.^[51][20] Owing to its unique stimulant properties among racetams, phenylpiracetam is the only racetam on the WADA prohibited list.^[50]

Research

Phenylpiracetam has been studied in the treatment of stroke and glaucoma.^[2]

The more active enantiomer of phenylpiracetam, (R)-phenylpiracetam, was under development for fatigue related to Parkinson's disease.^[9] However, no recent development has been reported.^[9] There was also interest in the compound for fatigue related to depression and other conditions, but this was not pursued.^[52][6] (R)-Phenylpiracetam has been identified as a selective atypical dopamine reuptake inhibitor (DRIs), and similarly to other DRIs, shows pro-motivational effects in animals and reverses motivational deficits.^[53][54][6]

See also

• Phensuximide – a succinimide analogue
• Phenibut – also included in Russian cosmonaut medical kits
• List of Russian drugs

References

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2. Malykh AG, Sadaie MR (February 2010). "Piracetam and piracetam-like drugs: from basic science to novel clinical applications to CNS disorders". Drugs. 70 (3): 287–312. doi:10.2165/11319230-000000000-00000. PMID 20166767.
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4. Veinberg G, Vavers E, Orlova N, Kuznecovs J, Domracheva I, Vorona M, et al. (2015). "Stereochemistry of phenylpiracetam and its methyl derivative: improvement of the pharmacological profile". Chemistry of Heterocyclic Compounds. 51 (7): 601–606. doi:10.1007/s10593-015-1747-9. ISSN 0009-3122. Phenylpiracetam was originally designed as a nootropic drug for the sustenance and improvement of the physical condition and cognition abilities of Soviet space crews.2 Later, especially during the last decade, phenylpiracetam was introduced into general clinical practice in Russia and in some Eastern European countries. The possible target receptors and mechanisms for the acute activity of this drug remained unclear, until very recently it was found that (R)-phenylpiracetam (5) (MRZ-9547) is a selective dopamine transporter inhibitor that moderately stimulates striatal dopamine release.19
5. Voronina TA (2023). "Cognitive Impairment and Nootropic Drugs: Mechanism of Action and Spectrum of Effects". Neurochemical Journal. 17 (2). Pleiades Publishing Ltd: 180–188. doi:10.1134/s1819712423020198. ISSN 1819-7124. Phenylpiracetam, a phenyl analogue of piracetam (trade names: phenotropil, carphedon, and phenylpiracetam), was developed at the Institute of Biomedical Problems as a new generation psychostimulant that can increase the mental and physical performance of astronauts at various stages of space flights. It was experimentally established that phenylpiracetam improves learning and memory, has an antiamnesic effect, activates operant behavior, has anxiolytic, antiasthenic, and anticonvulsant effects, weakens the sedative effect of benzodiazepines, increases resistance to cold, and improves sleep [29–31]. In a model of cerebral ischemia, phenylpiracetam improves cognitive functions, reduces manifestations of neurological deficit, and is superior in effectiveness to piracetam [32, 33]. It has been shown that phenylpiracetam does not bind to GABA-A, GABA-B and dopamine receptors, or 5-HT2 serotonin receptor, but is a synaptic transmission modulator and binds to α4β2 nicotinic acetylcholine receptors in the cerebral cortex (IC50 = 5.86 μm) [34, 35].
6. Sommer S, Danysz W, Russ H, Valastro B, Flik G, Hauber W (December 2014). "The dopamine reuptake inhibitor MRZ-9547 increases progressive ratio responding in rats". The International Journal of Neuropsychopharmacology. 17 (12): 2045–2056. doi:10.1017/S1461145714000996. PMID 24964269. Here, we tested the effects of MRZ-9547 [...], and its l-enantiomer MRZ-9546 on effort-related decision making in rats. The racemic form of these compounds referred to as phenotropil has been shown to stimulate motor activity in rats (Zvejniece et al., 2011) and enhance physical capacity and cognition in humans (Malykh and Sadaie, 2010). [...] MRZ-9547 turned out to be a DAT inhibitor as shown by displacement of binding of [125I] RTI-55 (IC50 = 4.82 ± 0.05 μM, n=3) to human recombinant DAT expressed in CHO-K1 cells and inhibition of DA uptake (IC50 = 14.5 ± 1.6 μM, n=2) in functional assays in the same cells. It inhibited norepinephrine transporter (NET) with an IC50 of 182 μM (one experiment in duplicate). The potencies for the l-enantiomer MRZ-9546 were as follows: DAT binding (Ki = 34.8 ± 14.8 μM, n=3), DAT function (IC50 = 65.5 ± 8.3 μM, n=2) and NET function (IC50 = 667 μM, one experiment performed in duplicate).
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20. EP application 20140000021, "Use of (r)-phenylpiracetam for the treatment of sleep disorders", published 2015-07-08, assigned to Merz Pharma GmbH and Co KGaA
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54. Salamone JD, Ecevitoglu A, Carratala-Ros C, Presby RE, Edelstein GA, Fleeher R, et al. (May 2022). "Complexities and paradoxes in understanding the role of dopamine in incentive motivation and instrumental action: Exertion of effort vs. anhedonia". Brain Research Bulletin. 182: 57–66. doi:10.1016/j.brainresbull.2022.01.019. hdl:10234/200412. PMID 35151797. Administration of TBZ reduces extracellular DA and DA D1 and D2 receptor signaling at doses that induce a low effort bias (Nunes et al. 2013). The effort-related effects of TBZ are reversible with DA agonists or drugs that block DA transport (DAT) and elevate extracellular levels of DA (Nunes et al. 2013a; Randall et al. 2014; Yohn et al. 2015a,b, 2016a,b,d; Salamone et al. 2016; Rotolo et al. 2019, 2020, 2021; Carratala-Ros et al., 2021b). Furthermore, DAT inhibitors such as lisdexamfetamine, PRX14040, MRZ-9547, GBR12909, (S)-CE-123, (S, S)-CE-158, CT 005404, as well as the catecholamine uptake inhibitor bupropion, increase selection of high-effort PROG lever pressing in rats tested on effort-based choice tasks (Sommer et al. 2014; Randall et al. 2015; Yohn et al. 2016a,b,d,e; Rotolo et al. 2019, 2020, 2021).

Further reading

• Arsenyeva KE (18 March 2007). "Опыт применения Фенотропила в клинической практике" [The Experience of Using Phenotropil in Clinical Practice] (HTML). РМЖ (Русский Медицинский Журнал) [RMS (Russian Medical Journal)] (in Russian) (6): 519. ISSN 2225-2282.

External links

• "Фенотропила" (Phenotropil) Search in the Russian Medical Journal