ACP-105

ACP-105 is a non-steroidal selective androgen receptor modulator developed by Acadia Pharmaceuticals. Classified as a partial androgen receptor agonist, ACP-105 was designed to deliver meaningful anabolic activity with a more conservative receptor activation profile than full AR agonists like RAD-140 or LGD-4033. Its partial agonist nature means it activates the androgen receptor to a submaximal degree — typically estimated at 60–70% of the efficacy of a full agonist — which translates to a proportionally reduced side-effect profile while retaining clinically relevant anabolic output.

ACP-105 binds the androgen receptor with high selectivity for skeletal muscle and bone over prostate and reproductive tissues. As a partial agonist, its receptor interaction kinetics differ fundamentally from full agonists: rather than driving maximal AR transcriptional activation, ACP-105 produces a modulated, dose-proportional anabolic response. In preclinical studies, ACP-105 demonstrated anabolic activity approximately 66% as potent as testosterone in the levator ani muscle assay while producing only minimal prostate stimulation — yielding a highly favorable anabolic-to-androgenic selectivity ratio.

Research positions ACP-105 as a compound with a particularly attractive risk-benefit profile for conservative research protocols. It delivers measurable lean mass accrual, improved strength, enhanced recovery, and bone-protective effects — all at a fraction of the suppressive and androgenic cost of more potent SARMs. Its partial agonist mechanism also means it is less likely to produce the receptor desensitization or post-cycle rebound effects that can complicate full agonist cycles.

ACP-105 is ideally suited for beginning researchers or those prioritizing minimal side effects over maximum anabolic potency. It serves as an excellent introductory compound before progressing to RAD-140 or LGD-4033, and is a strong choice for researchers in caloric deficit who seek lean tissue preservation without the suppression burden of more potent alternatives. Female researchers also find ACP-105 well-tolerated due to its lower virilization risk. It pairs effectively with Cardarine or SR-9009 for cutting protocols.

ACP-105 has an estimated elimination half-life of approximately 6 hours, which may necessitate twice-daily dosing for consistent plasma levels. Oral bioavailability is good. Testosterone suppression is mild — significantly less than RAD-140 or LGD-4033 at standard doses. Short, moderate-dose cycles (6–8 weeks at 5–10mg/day) may not require formal PCT, though a brief SERM protocol is advisable for cycles exceeding 8 weeks or doses above 10mg. No significant hepatotoxicity has been documented. Typical research protocols range from 5–15mg daily for 6–8 weeks.