Efficacy and acceptability of testosterone implants, alone or in combination with a 5alpha-reductase inhibitor, for male hormonal contraception.
Testosterone (T) treatment suppresses serum gonadotropins and reduces sperm output sufficiently for contraceptive efficacy in approximately 70% of Caucasian men. In the remaining 30% of men, an increase in 5alpha-reductase activity may maintain testicular androgen activity, thus accounting for the failure of sperm suppression. The form of T therapy is a major consideration in the safety and acceptability of T-based contraception. As compared to T ester injections, T implants provide a more physiological serum T profile and fewer side effects, but have not yet been used in contraceptive efficacy studies. We have used T implants (800-1200 mg every 3 months) in 29 normal men for 3-16 months. T implants produced long-term suppression of sperm densities below 1 million/mL in approximately 70% of men without significant androgenic side effects. No pregnancies occurred in 214 months of exposure. In 16 men failing to suppress within 3 months of T 800 mg, no evidence of enhanced spermatogenic suppression was seen with the co-administration of the type 2 5alpha-reductase inhibitor, finasteride, for 3 months when compared to placebo. We conclude that: 1) T implants provide adequate spermatogenic suppression in approximately 70% of Caucasian men, a rate comparable to intramuscular T injections but with minimal side effects; and, 2) the inclusion of a type 2 5alpha-reductase inhibitor does not enhance spermatogenic suppression.
McLachlan
R I
RI
Prince Henry's Institute of Medical Research, Monash Medical Centre, Clayton Road, Clayton, Victoria, Australia. rob.mclachlan@med.monash.edu.au
McDonald
J
J
Rushford
D
D
Robertson
D M
DM
Garrett
C
C
Baker
H W
HW
D058891:5-alpha Reductase Inhibitors; D000328:Adult; D003267:Contraception; D003692:Delayed-Action Preparations; D005640:Follicle Stimulating Hormone / Q000097:blood; D006801:Humans; D007265:Inhibins / Q000097:blood; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D008875:Middle Aged; D013076:Sperm Count; D013094:Spermatozoa / Q000187:drug effects; D013739:Testosterone / Q000008:administration & dosage* / Q000097:blood
D058891:5-alpha Reductase Inhibitors; D003692:Delayed-Action Preparations; D013739:Testosterone; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone