An evaluation of the anti-androgen effects associated with H2 antagonist therapy

The effect of two different H2-receptor antagonists, nizatidine and cimetidine, on sperm counts and hypothalamic-pituitary-gonadal function as determined by responses to provocative gonadotropin releasing factor, GnRH, thyrotropin releasing factor, TRH, and clomiphene were compared to those of men receiving placebo medication. All subjects studied gave informed written consent and were greater than 18 but less than 55 years of age. Sperm concentrations in collected semen specimens, and GnRH and TRH responses before and after 6 weeks of drug exposure were assessed as were the gonadotropin responses to clomiphene while on the drug for an additional 3 weeks. All had normal sperm concentrations and hormone levels before drug exposure and normal responses to both GnRH and TRH. Following drug exposure, the LH response to GnRH and the growth hormone, prolactin, TSH and T4 responses to TRH were similar to those obtained prior to drug use. Sperm concentrations were unchanged in both placebo and nizatidine exposed men, but were significantly reduced (p less than 0.05) in the cimetidine exposed men. Based on these data, nizatidine does not appear to influence hormone function or fertility.