MK-0773

Muscle Growth & Body Composition

Also known as: MK0773, PF-05314882

Selective Androgen Receptor ModulatorsResearch phase: Phase 2 (discontinued)Regulatory: Not FDA-approved. Development discontinued due to hepatotoxicity signals.

Mechanism

MK-0773 is a steroidal SARM that completed a Phase 2 trial for sarcopenia (age-related muscle loss) in elderly women. It showed improvements in lean body mass but was associated with elevated liver enzymes, which limited further development.

Technical detail

MK-0773 is a 4-aza-steroidal SARM that was evaluated in a Phase 2 randomized controlled trial in frail elderly women with sarcopenia and functional limitations. Over 6 months, it produced statistically significant increases in lean body mass versus placebo. However, the trial revealed dose-dependent hepatic transaminase elevations (ALT/AST) that constituted a safety concern, limiting further clinical development. Its steroidal backbone distinguishes it from most SARMs in development.

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