ACP-105 Side Effects: What the Research Actually Shows

Key takeaways

No Registered Human Trials Exist

ACP-105 is a nonsteroidal selective androgen receptor modulator (SARM) that has not advanced to any registered human clinical trial. The published literature on the compound consists of rodent pharmacology studies, in vitro liver metabolism experiments, and computational (in silico) toxicology modeling, but no controlled study in human volunteers.

The closest thing to a human data point is a single urine sample collected after a 100 microgram dose of ACP-105, which anti-doping chemists used to identify metabolites for detection purposes rather than to evaluate safety. <cite index="18-3">The in vitro derived metabolites were used as analytical targets in doping control by comparison with results from a human post-administration urine sample collected after a single dose of 100 µg ACP-105.</cite> This was a forensic or anti-doping specimen, not a monitored clinical study, so it provides no information about tolerability, adverse events, or dosing effects in people and should not be interpreted as clinical safety data.

What Animal Studies Show

Preclinical characterization work describes ACP-105 as tissue-selective in its androgen receptor activity. <cite index="11-9">From these experimental findings, ACP-105 has been shown to exert strong anabolic effects in muscle tissue while having reduced activity in androgen-sensitive tissues like the prostate, suggesting tissue selectivity.</cite> This pattern, anabolic action in muscle with comparatively less stimulation of prostate tissue, is the general rationale behind SARM development as an alternative to testosterone and anabolic steroids, but it comes from rodent experiments and has not been verified in humans.

Separate rodent work has examined neurological and behavioral endpoints. In a study of irradiated and sham-irradiated female mice, <cite index="36-1,36-2">irradiation impaired sensorimotor function in vehicle-treated mice but not in ACP-105-treated mice, and irradiation impaired cued fear conditioning while ACP-105 enhanced fear conditioning in sham-irradiated and irradiated mice.</cite> The same study found brain-region-specific changes in a structural protein marker: <cite index="36-3,36-4,36-5">when immunoreactivity for microtubule-associated protein 2 was assessed in the cortex of sham-irradiated mice, ACP-105 reduced MAP-2 immunoreactivity in the sensorimotor cortex, with a trend toward increased immunoreactivity in the entorhinal cortex, while no effect was seen in the hippocampus.</cite>

A separate study in a transgenic mouse model of Alzheimer's disease reported that <cite index="39-1">ACP-105 given alone decreases anxiety-like behavior</cite>, and that combining it with a selective estrogen receptor beta agonist produced additional effects on amyloid-beta metabolism and spatial memory measures. These are mechanistic, hypothesis-generating findings from genetically modified mice under specific experimental conditions. They have not been replicated in other animal models or tested in any human study, and behavioral effects seen in mice, whether protective or otherwise, cannot be assumed to translate to people.

Metabolism and Computational Toxicology Findings

Because there is no living-human pharmacokinetic data, researchers have relied on in vitro liver preparations and computer modeling to estimate how ACP-105 might behave in the body. An integrative in silico ADME analysis using multiple prediction platforms concluded that <cite index="11-4,11-5">metabolic profiling identified six metabolites (M1 to M6), primarily formed via CYP3A4, with additional contributions from CYP2C9, CYP2C19, and CYP2D6, and that ACP-105 is a consistent substrate for CYP3A4 (82 to 100%), likely undergoing stable and unstable oxygenation, N-dealkylation, and UGT conjugation.</cite> The same modeling predicted <cite index="11-3,11-7">clearance predictions varying from 7.175 to 3.86 × 10⁻⁵ mL/min/kg, with a short half-life of approximately 1.18 hours, and blood-brain barrier penetration in most models.</cite>

This predicted reliance on CYP3A4 metabolism is not purely theoretical. It is corroborated by laboratory experiments using actual liver tissue preparations: researchers incubated ACP-105 with <cite index="19-2">microsomes and S9 fractions of both human and equine origin</cite> and separately dosed horses directly, comparing the resulting metabolites. A related analytical paper confirmed metabolite findings using <cite index="23-5">human liver microsomes (M) or human liver S9 fractions (S9)</cite>. So while no living person has been studied pharmacokinetically in a controlled trial, the CYP3A4-mediated metabolism prediction has support from experiments on human-derived liver tissue and from live animal dosing, not from rodent studies alone.

A separate in silico toxicology paper screened ACP-105 across a wider battery of computational endpoints. <cite index="15-3">This work aimed to use various in silico techniques to predict the toxicity of ACP-105, including acute toxicity, effects on internal organs, genotoxicity based on the Ames test, eye and skin irritation, and cardiotoxicity by testing hERG inhibitors.</cite> The publicly available summary of this study describes the endpoints tested but does not specify the magnitude or direction of the hERG-related prediction, so it is accurate to say that cardiac liability was one of the parameters screened, but overstating this into a confirmed arrhythmia risk would not be supported by the available evidence. The same ADME modeling separately flagged theoretical <cite index="11-2">interactions with DNA/protein and potential cyanide release</cite> as computational predictions; these are structural alerts generated by prediction software, not findings from a biological experiment, and their real-world relevance is unknown.

What Is Known About SARMs as a Drug Class

Because ACP-105 itself has no clinical safety record, much of what is written about its risks is extrapolated from the broader SARM class, which has been studied more extensively, including in some early-phase human trials of other compounds, and has an established pattern of adverse effects documented by regulators and clinicians.

The FDA has directly warned that products containing SARMs carry serious risks. <cite index="31-16,31-17">Life-threatening reactions, including liver injuries that required hospitalization, have occurred in people taking products containing SARMs, which also have the potential to cause increased risk of heart attack or stroke, psychosis and hallucinations, sleep disturbances, sexual dysfunction, liver injury and acute liver failure, infertility, pregnancy miscarriage, and testicular shrinkage.</cite> The agency has also noted that <cite index="31-11,31-15">these bodybuilding products often contain SARMs and have not been approved by the FDA, and are unapproved drugs that FDA has not reviewed for safety and effectiveness.</cite>

Anti-doping authorities describe similar concerns. <cite index="26-3">Athletes have also reported consuming SARMs at much higher doses than clinically studied, which may increase the risk of reported side effects such as liver injury, impaired insulin sensitivity, cardiovascular events, and tendon damage.</cite> More recent case literature has gone further: <cite index="26-7">recent case reports associate the use of SARMs with harmful effects like drug-induced liver injury, myocarditis, and tendon rupture.</cite> A recurring theme in these sources is uncertainty about long-term consequences: <cite index="26-4">the long-term effects of using SARMs are unknown.</cite>

None of these reports are specific to ACP-105, since none involve confirmed, verified use of that particular compound in a monitored setting. They describe the class as a whole, most often compounds with more human exposure data, such as ostarine (enobosarm), ligandrol (LGD-4033), and RAD140. Whether ACP-105 carries the same magnitude of risk is not established, but there is no pharmacological reason to assume it is exempt from the androgen-receptor-mediated mechanisms thought to underlie these effects.

Regulatory Status: Not Approved, Not a Supplement

No SARM, including ACP-105, is approved by the FDA for any medical use in the United States. <cite index="26-8,26-9">All SARMs are for investigational purposes only, meaning they are not approved by the FDA for human use; they are not drugs that a doctor can prescribe, and they are also not legal for use in compounded medicines or dietary supplements.</cite> Products marketed online as ACP-105 are therefore unregulated research chemicals rather than approved pharmaceuticals or lawful supplements, and their actual contents and purity are not verified by any regulatory body.

Is ACP-105 Banned in Sport?

SARMs as a class have been prohibited in competitive sport since 2008. <cite index="5-3">Since their inclusion into the WADA Prohibited List in 2008, there has been an increase in not only the number of adverse analytical findings, but also the total number of SARMs, making continuous research into SARMs an ongoing topic in the field of doping controls.</cite> SARMs are listed under the anabolic agents category of the Prohibited List, and <cite index="26-10">all SARMs are prohibited at all times (both in and out-of-competition) for all athletes, from those competing at the highest level of sport to those competing at the recreational level.</cite>

ACP-105 specifically has drawn attention from anti-doping laboratories because it is a comparatively new designer SARM. <cite index="12-1">ACP-105 is a novel non-steroidal selective androgen receptor modulator (SARM), increasingly detected in anti-doping analyses, yet lacking a comprehensive ADME profile.</cite> To close that gap, researchers have characterized its metabolites in both equine and human-derived laboratory models: <cite index="16-9,16-10">the aim of one study was to investigate the metabolite profile of ACP-105 in order to find analytical targets for doping control, with oral administration performed in horses and in vivo samples compared with in vitro incubation models encompassing microsomes and S9 fractions of both human and equine origin.</cite> This kind of work is done specifically to extend detection windows, since <cite index="17-9">the use of a drug metabolite as an analytical target often increases the detection time, since drug metabolites can be present in biological matrices such as blood and urine for an extended time.</cite> It is worth being precise about terminology here: "human-relevant" in this context means human liver tissue preparations used in a laboratory dish, not living human volunteers dosed under medical supervision.

Athletes who test positive for ACP-105 or its metabolites are subject to sanction under the applicable anti-doping rules, consistent with the general principle that SARMs are prohibited at all times for competitors at every level, as noted above.

Gray-Market Products and Verification Problems

Because ACP-105 is not an approved drug, products sold under that name are not manufactured, labeled, or tested under any pharmaceutical quality standard. Purity, actual dose, and even the presence of the labeled compound cannot be verified in over-the-counter or online "research chemical" products. This means that anecdotal reports of effects or side effects from people who believe they have used ACP-105 cannot be reliably attributed to that specific molecule, since contamination, mislabeling, or substitution with other substances is a documented problem across the unregulated SARM market generally, as reflected in FDA warnings about these products being sold without accurate labeling.

Frequently asked

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