Cimetidine is an H2 blocker currently available over the counter for treatment of heartburn, ulcers, and gastroesophageal reflux. It appears to exert its toxic effects directly on the testicle, possibly by preventing the binding of dihydrotestosterone (DHT) to the androgen receptor, and can also elevate prolactin levels that inhibit the HPG axis. Spermatogenesis may also be impaired due to interruption of the normal pulsatile secretion of LH from the pituitary. In animals treated with cimetidine, testicular atrophy and hyperplasia of Sertoli and Leydig cells have been demonstrated, but this has not been a consistent finding.[32,33] Most animal studies have not achieved statistical significance in demonstrating a decrease in testicular volume.[32,33] In human studies, no elevation of DHT, FSH, or LH has been observed.
Semin Reprod Med. 2013;31(4):286-292. © 2013 Thieme Medical Publishers