SARM Pharmacokinetics

The vast majority of SARMs that have been reported are nonsteroidal. Notable exceptions are a series of Merck patents (see above) and MENT [229]. Thus, it can be expected that many of the pharmacokinetic (what the body does to the drug absorption, distribution, metabolism and excretion) and pharmacodynamic (what the drug does to the body pharmacologic, phenotypic and toxicologic effects) problems inherent to the steroid nucleus may be absent in SARMs. Pharmacokinetic/pharmacodynamic profiles have been published for a number of nonsteroidal SARMs [230]. 

Pharmacokinetics Absorption bioavailability topical and intramuscular complete oral 

Toxicity hepatotoxicity (AAS) no major toxicity through phase II 

Pharmacodynamics Androgenicity liability for cancer, hirsutism, decrease in prostate 

Hypothalmic-pitui- major effect (suppresses minor effect at high 

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Table 8.1 Pharmacokinetics and pharmacodynamics of nonsteroidal SARMs vs. traditional steroidal androgens.

These improved pharmacokinetic and side-effect profiles for SARMs versus steroidal androgens are associated with potent, tissue-selective effects in therapeutic target tissues. Hyperanabolic effects in skeletal muscle have been seen for SARMs in rat for numerous molecules [90, 151, 176, 184] with myoanabolic effects in castrated rats in the range of 100-150% compared to testosterone. These effects have also been seen in human trials as manifested by increases in LBM and improvements in physical performance tests (stair climb time [96]). Osteoanabolic effects have also been demonstrated in rats [95, 128, 151] and monkeys [130] for numerous molecules however, only limited clinical trials data have been released in human [128],... 

Wu, D., Wu, Z., Yang, J., et al. (2006) Pharmacokinetics and metabolism of a selective androgen receptor modulator (SARM) in rats—Implication of molecular properties and intensive metabolic profile to investigate ideal pharmacokinetic characteristics of a propanamide in preclinical study. Drug Metabolism and Disposition, 34,483-494. 

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