spec sheet11 rows
MRZ-9547 is the R-enantiomer of phenylpiracetam (R-fonturacetam), developed by Merz Pharmaceuticals as a selective dopamine transporter (DAT) inhibitor for the fatigue and reduced motivation of Parkinson's disease [1][2]. In rats it dose-dependently increases effort-related responding and reverses motor deficits in Parkinson models, moderately raising striatal dopamine release, while its L-enantiomer MRZ-9546 is far less active [1][2]. It should not be conflated with racemic phenylpiracetam: MRZ-9547 is a single, defined enantiomer studied specifically as a DAT-based anti-fatigue agent [2].
- Selective dopamine transporter inhibition that raises dopamine tone
- Strongly increases motivation and effort-based responding in animals
- Preclinical anti-fatigue effect relevant to Parkinson's disease
- Can enhance L-DOPA benefit without increasing dyskinesia in models
- Potential for raised heart rate, blood pressure, insomnia and anxiety.
- Possible abuse or dependence liability as a dopaminergic reuptake inhibitor.
- Risky in combination with other dopaminergic drugs, stimulants or MAO inhibitors.
Overview
MRZ-9547, chemically d-(2-(2-oxo-4(R)-phenylpyrrolidin-1-yl)-acetamide), is the (R)-enantiomer of the well-known nootropic phenylpiracetam (fonturacetam). Where the racemic parent is used as a mild psychostimulant, Merz Pharmaceuticals isolated and studied this single enantiomer as a selective inhibitor of the dopamine transporter, aiming at the motivational and fatigue symptoms that trouble Parkinson's disease patients [1][2].
In rodent models predictive of antiparkinsonian activity, MRZ-9547 attenuated haloperidol- and monoamine-depletion-induced hypolocomotion and produced dose-dependent rotational behavior in unilaterally 6-hydroxydopamine-lesioned rats, indicating action on partially intact dopaminergic terminals; it also enhanced the effect of L-DOPA without worsening L-DOPA-induced dyskinesia [1]. In a separate line of work it increased progressive-ratio responding and shifted effort-related decision making toward high-effort options more strongly than methylphenidate, modafinil or amphetamine, a profile relevant to fatigue in neurological and neuropsychiatric disorders [2]. Microdialysis confirmed that it is a selective DAT inhibitor that moderately stimulates striatal dopamine release and penetrates the brain well [1][2].
The compound remains preclinical, supplied as a research chemical. Its interest lies in demonstrating that resolving phenylpiracetam into a single enantiomer yields a cleaner dopamine-transporter tool aimed at motivation and energy rather than general stimulation.
- MRZ-9547 increased rats' willingness to work for a reward more powerfully than methylphenidate, modafinil or amphetamine in the same effort-based task [2].
- It is simply the R-enantiomer of phenylpiracetam, and its mirror-image twin MRZ-9546 is a much weaker dopamine transporter inhibitor, a clean illustration of how chirality changes drug activity [2].
Mechanism
MRZ-9547 acts as a selective inhibitor of the (), blocking reuptake of and thereby increasing extracellular dopamine in the striatum; in vitro assays and in vivo microdialysis confirm both DAT selectivity and a moderate increase in striatal dopamine release [2]. This dopaminergic action underlies its behavioral effects on motivation and motor drive.
In Parkinson models the drug attenuates -deficit-induced hypolocomotion and augments the response to L-DOPA, consistent with amplifying signaling at remaining dopaminergic terminals rather than acting downstream of receptor loss [1]. Functionally, this translates into a striking increase in effort-related responding, the willingness to work harder for reward, which is a recognized correlate of anti-fatigue and pro-motivational activity; notably its L- MRZ-9546 is a much weaker inhibitor, underscoring the enantioselectivity of the effect [2].
receptor fingerprint
Effort-related respondingIncreases
()Inhibits
L-DOPA antiparkinsonian effectEnhances
Dosingtypical ranges, not medical advice
interested in protocols and clinical dosages? make an account to see them! ^_^
Safetyrisks and cautions, not medical advice
MRZ-9547 has not been through published human safety testing, so its side-effect and interaction profile in people is unknown. As a dopamine transporter inhibitor it belongs pharmacologically with stimulant-type drugs, and the predictable cautions apply: potential for raised heart rate and blood pressure, insomnia, appetite suppression, anxiety and, in theory, abuse or dependence liability, plus risky interactions with other dopaminergic or serotonergic agents and MAO inhibitors. It is a research chemical, not an approved medicine or supplement, and should be treated as research-use-only. Anyone tempted to conflate it with over-the-counter phenylpiracetam should note it is a distinct, more targeted single enantiomer.
History
MRZ-9547 was developed by Merz Pharmaceuticals in Frankfurt, Germany, and characterized in a pair of 2014 studies by Dekundy, Sommer, Danysz and colleagues as a dopamine-uptake inhibitor for Parkinson's disease fatigue and motivational deficits [1][2]. It represents a deliberate enantiomeric refinement of phenylpiracetam (fonturacetam), a molecule with roots in earlier Soviet and Latvian nootropic chemistry.
Reputation
In the research literature MRZ-9547 is regarded as a well-characterized, selective DAT inhibitor with a compelling preclinical story for treating fatigue and low motivation, standing out for outperforming methylphenidate and modafinil on effort-based tasks [2]. Among nootropic users it is obscure and frequently misunderstood as merely a purer phenylpiracetam; the honest position is that it has promising animal data but no human trials, so its real-world value remains speculative.
Subjective profileweighing the evidence above
Preclinical only, and most of the enthusiasm around it comes from confusing it with over-the-counter phenylpiracetam, which it is not. As a dopamine transporter blocker it carries the full stimulant-class caution list including dependence liability, with no human safety data to bound any of it.
Resources
This entry is here for reference.
Research
- 1.Effects of dopamine uptake inhibitor MRZ-9547 in animal models of Parkinson's disease.
- 2.The dopamine reuptake inhibitor MRZ-9547 increases progressive ratio responding in rats.
2 listed here; entry last updated August 2026
Reviews
My notesprivate to this device
FAQ
Is MRZ-9547 just phenylpiracetam?
No. It is the isolated R-enantiomer of phenylpiracetam, studied as a targeted dopamine transporter inhibitor, which behaves differently from the racemic mixture sold as phenylpiracetam.
What was it developed for?
Merz developed it for the fatigue and reduced motivation seen in Parkinson's disease, based on its ability to raise dopamine and increase effort-related behavior.
Does it work in humans?
That is unknown. The evidence is entirely preclinical, so there are no human efficacy or safety results yet.
Why does the enantiomer matter?
Its mirror-image form MRZ-9546 is a far weaker dopamine transporter inhibitor, so the R configuration carries most of the activity.
Limitations of the evidence
- No human safety data; stimulant-class risks are presumed but uncharacterized.
Adverse effects
- Potential for raised heart rate, blood pressure, insomnia and anxiety.
- Possible abuse or dependence liability as a dopaminergic reuptake inhibitor.
- Risky in combination with other dopaminergic drugs, stimulants or MAO inhibitors.