Clinical Trial of 7-Methyl-19-Nortestosterone Implants for Possible Use as a Long-Acting Contraceptive for Men
Sigrid von Eckardstein, Gabriela Noe, Vivian Brache, Eberhard Nieschlag, Horacio Croxatto, Francisco Alvarez, Alfred Moo-Young, Irving Sivin, Narender Kumar, Margaret Small and Kalyan Sundaram
Institute of Reproductive Medicine, University of Munster (S.v.E., E.N.), Munster, Germany; Instituto de Medicina Reproductiva (G.N., H.C.), Correo 22, Casilla 96 Santiago, Chile; PROFAMILIA (V.B., F.A.), Apartado Postal 1053, Santo Domingo, Dominican Republic; and The Population Council (A.M.-Y., N.K., M.S., I.S., K.S.), New York, New York 10021
Address all correspondence and requests for reprints to: Dr. Kalyan Sundaram, Center for Biomedical Research, Population Council, 1230 York Avenue, New York, New York 10021. E-mail:
kalyan@popcbr. rockefeller.edu.
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 7-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 5-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 months for the 2-implant group and to 12 months for the 4-implant group. Dose-related increases in serum MENT levels and decreases in testosterone, LH, and FSH levels were observed. Effects on sperm counts were also dose related. None of the subjects in the 1-implant group exhibited oligozoospermia (sperm count, <3 million/ml). Four subjects in the 2-implant group became oligozoospermic, 2 of whom reached azoospermia. Eight subjects in the 4-implant group reached azoospermia, with 1 exhibiting oligozoospermia, whereas 2 were nonresponders. Side effects generally seen with androgen administration, such as increases in erythrocyte count, hematocrit, and hemoglobin and a decrease in SHBG, were also seen in this study and were reversible. Changes in lipid parameters were moderate and transient. Liver enzymes showed small changes. This study demonstrates that MENT Ac, when administered in a sustained release fashion via subdermal implants, can inhibit spermatogenesis over a prolonged period after a single administration and has the potential to be used as a male contraceptive.
This work was supported by the U.S. Agency for International Development (Cooperative Agreement HRN-A-00-99-00010-00), the United Nations Population Fund, the NIH (Center Grant U54-HD-29990), the Andrew W. Mellon Foundation, the Bingham Trust, the Educational Foundation of America, the Lila Annenberg Hazen Foundation, the George Hecht Family Trust, and the William and Flora Hewlett Foundation.
Preliminary results of this study were presented in abstract form at the VIIth International Congress of Andrology, Montreal, Canada, 2001.
Abbreviations: Ac, Acetate; BP, blood pressure; CV, coefficient of variation; MENT, 7-methyl-19-nortestosterone; PSA, prostate-specific antigen; T, testosterone; TE, testosterone enanthate; TU, testosterone undecanoate.