Reversible inhibition of sperm production and gonadotrophin secretion in men following combined oral medroxyprogesterone acetate and percutaneous testosterone treatment.

Abstract

Six men requesting male contraception received a daily oral dose of 20 mg medroxyprogesterone acetate (MPA) in combination with 50 or 100 mg percutaneous testosterone for 1 year. From the third month the sperm concentration was less than 10(6)/ml for all the men at one time or another during treatment, and usually less than 5 X 10(6)/ml, with an average reduction of 95% with respect to pre-treatment values. The sperm count returned to previous values 3-6 months after cessation of the treatment. While FSH and LH secretion was inhibited throughout the treatment period, plasma testosterone levels were not reduced. Oestradiol levels were unaffected while dihydrotestosterone was elevated. The secretory activity of the prostate and seminal vesicles was not appreciably affected; seminal carnitine concentration was reduced during the treatment with a subsequent return to pretreatment values. No pregnancies occurred during treatment. There was no impairment of libido in the subjects, nor any incidence of gynaecomastia, or increase in average body weight. The only observed metabolic side-effect was a moderate increase in glycaemia. A synergistic action of MPA and testosterone is proposed to explain the inhibition of gonadotrophin secretion.