Endocrine Abstracts

Objectives: To assess the gonadotrophin suppressive effects of 2 doses of nomegestrol acetate (NOMA) alone and in combination with testosterone enanthate (TE) in men.

To evaluate the potential effects of NOMA on circulating lipids in men

Methods: Twelve healthy male volunteers were recruited. Subjects were randomly allocated to receive either NOMA 5 milligrams or NOMA 10 milligrams orally daily. Study duration included 28 days treatment and 28 days recovery. NOMA was administered for 28 days with a single im injection of 100 milligrams of TE on day 21. Central Manchester Research and Ethics Committee gave ethical approval for this study.

Results: NOMA alone suppressed LH from 3.2 plus/minus 0.8 to 1.3 plus/minus 0.3 at day 21 and 3.7 plus/minus 0.6 to 1.6 plus/minus 0.3 units per litre in the 5 and 10 milligram groups respectively. Following the addition of TE, LH in both groups suppressed further to the lower limit of the assay (LOQ equals less than 0.1 units per litre). NOMA alone suppressed FSH from 2.6 plus/minus 0.6 to 1.1 plus/minus 0.3 units per litre at day 21 and 3.2 plus/minus 0.3 to 1.4 plus/minus 0.2 units per litre in the 5 milligram and 10 milligram groups respectively. Addition of TE suppressed FSH further to 0.2 plus/minus 0.1 and 0.3 plus/minus 0.1 in the 5 and 10 milligram groups respectively on day 28. Testosterone in both groups decreased to nadir values of 4.0 plus/minus 0.5 (5 milligrams) and 2.8 plus/minus 0.5 nanomols per litre (10 milligrams) prior to TE injection at day 21. All hormone parameters rapidly returned to normal during recovery. There was no effect of treatment on lipids, haemoglobin, haematocrit or PSA.

Conclusion: NOMA when administered alone or in combination with TE significantly suppressed pituitary gonadotrophins without adverse metabolic effects. NOMA is a potential candidate oral progestin for male hormonal contraception. Further investigations on the effects of NOMA on suppression of spermatogenesis are in progress.