Clinical trial with subdermal implants containing norgestrienone.
Norgestrienone implants delivering approximately 225 microgram/ day were tested clinically for contraceptive effectiveness and acceptability in 145 women. Five pregnancies occurred in 2259 woman-months of use, one in the 11th month, one in the 15th and three in the 16th month of use. Continuation rate at 12 months was 86.7. The number of bleeding runs and bleeding days was increased in approximately 12% of the subjects. Ten percent of the patients had no bleeding in the first 90 days of treatment. Changes in bleeding pattern led to closures in four cases. Headache and signs of mild androgenicity were among the leading side effects. Blood and urine analysis throughout the study showed normal values of 17 different parameters, but a tendency to lower cholesterolemia not associated with changes in thyroid hormone levels, was observed in several patients. Cortisol was found slightly under the lower normal range in one subject without clinical manifestations of hypoadrenalism. It is concluded that norgestrienone implants should be replaced every twelve months for maximal contraceptive effect and because of their efficacy and good acceptability, evaluation of their long term use is warranted.