ACP-105 Cycle: What the Research Actually Supports

Key takeaways

What ACP-105 Is

ACP-105 is a non-steroidal selective androgen receptor modulator (SARM) that was investigated by ACADIA Pharmaceuticals in the mid-2000s. The company's own preclinical characterization, presented at the Experimental Biology 2008 meeting, described ACP-105 as being as potent and efficacious as testosterone in vitro without meaningful activity at other hormone receptors, with anabolic effects on muscle and bone and minimal effect on the prostate in animal models.

The underlying chemistry and structure-activity data were later published in a peer-reviewed paper. According to the Wikipedia entry on the compound, which cites the primary chemistry literature, the foundational paper describing ACP-105 and related nonsteroidal androgen receptor modulators appeared in the Journal of Medicinal Chemistry in November 2009.

Public information indicates the program did not progress beyond this preclinical and early discovery stage. No sponsor has registered or reported completed human clinical trials of ACP-105 in ClinicalTrials.gov or the published literature reviewed for this article.

Preclinical Pharmacology

In receptor-binding assays, ACP-105 has been reported to bind the androgen receptor with high affinity, with pEC50 values of 9.0 for wild-type androgen receptor and approximately 9.3 to 9.4 for the T877A androgen receptor mutation, according to chemical supplier technical data derived from the original discovery research.

The tissue-selectivity claim associated with ACP-105, and with SARMs generally, is that the compound activates androgen receptor signaling preferentially in muscle and bone while producing less stimulation of prostate tissue, an effect pattern reported in ACADIA's own preclinical presentation. This is an animal pharmacology finding, not a demonstrated clinical outcome in humans.

A 2025-2026 in silico ADME (absorption, distribution, metabolism, excretion) analysis, built from seven independent computational modeling platforms, predicted high gastrointestinal absorption, moderate lipophilicity, strong plasma protein binding, and metabolism primarily through CYP3A4 with additional contributions from CYP2C9, CYP2C19, and CYP2D6. The same modeling predicted a short elimination half-life, on the order of just over an hour, and blood-brain barrier penetration in most models. It is important to note these are computational predictions, not measurements from human subjects.

The Neurological Research Angle

Separately from the muscle and bone research, ACP-105 has been studied in rodent models of cognitive decline. The Wikipedia entry for the compound, sourced to the primary literature, notes it has been investigated for potential relevance to age-related cognitive decline in animal models, including work combining SARMs and estrogen receptor beta agonists in a mouse model of amyloid-beta pathology.

This body of work remains confined to rodent models. It does not establish any cognitive benefit, protective effect, or safety profile in humans, and no human trial in this area has been identified.

Toxicology Data Is Almost Entirely Computational, Not Clinical

A dedicated in silico toxicology study of ACP-105 states plainly that its safety profile remains insufficiently explored, particularly regarding toxicity in humans, and that this gap was the motivation for the analysis. The authors note the compound is used by athletes despite this absence of safety data.

A related ADME/toxicology paper explains that the modeling work was undertaken specifically because of the lack of additional clinical or toxicological data on ACP-105, and it flags computationally predicted concerns including potential interactions with DNA and protein and possible release of cyanide from the compound's nitrile chemical group. These are theoretical, model-derived flags intended to guide further investigation and forensic interpretation, not confirmed clinical toxicities.

No human pharmacokinetic study, human tolerability study, or human adverse-event case series specific to ACP-105 was located in the peer-reviewed literature searched for this article.

Why No Legitimate Human "Cycle" Exists

A dosing protocol or cycle length that has clinical meaning requires human pharmacokinetic and safety data: absorption and clearance in people, a tolerated dose range, and monitoring for organ-specific effects such as liver enzyme changes or lipid shifts. None of this exists for ACP-105.

Figures that circulate online, such as human-equivalent doses back-calculated from a rodent milligram-per-kilogram dose, are mathematical conversions of animal data. They do not account for interspecies differences in metabolism, protein binding, or receptor pharmacodynamics, and they have not been validated in any human study. The in silico ADME work discussed above was undertaken specifically because clinical and toxicological data in humans do not exist, which underscores that any human dosing figure attached to ACP-105 online is an extrapolation, not a verified clinical parameter.

Because ACP-105 was discontinued at the preclinical stage and never entered registered human trials, there is no regulatory-reviewed information on how it behaves in the human body over repeated dosing, what an appropriate monitoring interval would be, or what constitutes a harmful cumulative exposure.

Regulatory and Legal Status

No SARM, including ACP-105, is approved by the FDA for any medical use. The FDA has issued a consumer warning stating that SARMs are chemical substances that mimic the effects of testosterone and anabolic steroids and are not FDA approved, and that the agency continues to receive adverse event reports associated with SARM use, including reports of increased risk of heart attack or stroke, psychosis or hallucinations, sleep disturbances, sexual dysfunction, liver injury and acute liver failure, infertility, pregnancy miscarriage, and testicular shrinkage.

SARMs as a class are listed under section S1.2 ("Other Anabolic Agents") of the World Anti-Doping Agency's Prohibited List and are banned at all times, both in and out of competition, as non-specified substances. ACP-105 itself has been reported with increasing frequency in anti-doping laboratory analyses, according to the ADME research discussed above, which describes it as a SARM increasingly detected in anti-doping analyses despite lacking a comprehensive characterization.

Products sold online as ACP-105 are typically labeled "for research use only" or "not for human consumption." This labeling does not change the substance's unapproved and prohibited status; it is a common practice used to sell unapproved research chemicals outside pharmaceutical regulatory channels.

What Class-Wide SARM Safety Data Show

Because human data on ACP-105 specifically does not exist, the closest available evidence comes from safety data on the SARM class as a whole, drawn mostly from other, more studied compounds. A systematic review of SARM safety in healthy adults identified 33 studies, including 15 case reports or case series and 18 clinical trials, covering more than 2,100 patients. Among the case reports, the review found instances of drug-induced liver injury, Achilles tendon rupture, rhabdomyolysis, and reversible liver enzyme elevation.

A separate pharmacovigilance-style review of suspected SARM-related adverse events likewise concluded that despite some SARMs having entered clinical trials, none has been approved by the FDA or the European Medicines Agency for any indication, and that long-term exposure effects in humans remain incompletely understood.

These findings describe SARMs generally, using data concentrated on compounds such as ostarine, ligandrol, and RAD140 that have actually been dosed in humans. They cannot be assumed to transfer directly to ACP-105, which has no equivalent human safety record, but they illustrate the type of harm reported within this drug class when human exposure does occur.

Bottom Line

ACP-105 is a preclinical-stage compound. Its androgen receptor binding, apparent tissue selectivity, and neuroprotective signals in rodents are documented in the pharmacology literature, but none of this has been confirmed in a completed human trial. Toxicology information is limited to computational (in silico) modeling performed because no clinical or laboratory toxicity data exist. No regulatory body has approved ACP-105 for any use, and SARMs as a class are prohibited in sport at all times. Any dosing schedule, cycle length, or human-equivalent dose presented online for ACP-105 is derived from rodent data or from unverified user reports, not from clinical research, and should be understood as such.

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