A Clinical Trial of 7α-Methyl-19-Nortestosterone Implants for Possible Use as a Long-Acting Contraceptive for Men

Several preparations of testosterone and its esters are being investigated alone or in combination with other gonadotropin-suppressing agents as possible antifertility agents for men. We studied the effectiveness of 7α-methyl-19-nortestosterone (MENT) as an antispermatogenic agent in men. MENT has been shown to be more potent than testosterone and to be resistant to 5α-reduction. For sustained delivery of MENT, we used a system consisting of ethylene vinyl acetate implants containing MENT acetate (Ac), administered subdermally. Thirty-five normal volunteers were recruited in 3 clinics and were randomly assigned to 1 of 3 doses: 1 (12 men), 2 (11 men), or 4 (12 men) MENT Ac implants. The initial average in vitro release rate of MENT Ac from each implant was approximately 400 μg/day. Implants were inserted subdermally in the medial aspect of the upper arm under local anesthesia. The duration of treatment was initially designed to be 6 months. However, in 2 clinics the duration of treatment was extended to 9...