METABOLISM OF ORALLY ADMINISTERED d-NORGESTREL IN WOMEN

The metabolism of D-norgestrel was studied in 5 women by administering either tritiated D-norgestrel alone or following 21 days of a daily dose of .5 mg unlabelled D-norgestrel. Plasma and urine analyses were done to determine the concentration and the metabolites within the sample every 4 days. In plasma the maximum concentration of tritiated D-norgestrel was found 4-6 hours after ingestion. This represents .2 to .4% of the administered dose/100 ml of plasma. The half-life of the tritium after 24 hours varied from 27 to 55 hours while after 24 hours 85% of the radioactivity is in a conjugated form. In the urine 41 to 67% of the administered radioactivity was recovered within 4 days half of it during the first day. The mean half-life of the tritium was 21 hours. 3.6 to 25.7% of the radioactivity was in an unconjugated form. The conjugated faction revealed the presence of n-acetylglucosaminides sulphates and glucuronides. Analysis of the urine showed the presence of 10 metabolites of D-norgestrel all but 1 more polar than the administered material. The administration of unlabelled D-norgestrel before the labelled drug had no effect on the metabolism except for a possible increase in the half-life of the tritium in plasma.(Authors modified)