Pharmacokinetics of norethindrone acetate in women.
The plasma half-life, MCR and plasma metabolite levels at various time intervals have been studied in six women after an intravenous injection of 3H-norethindrone acetate. The disappearance curve due to norethindrone acetate showed an initial rapid disappearance of 3H with an average half-life of 7.5 minutes and a subsequent slow disapperance with a half-life of 51.5 hours. Norethindrone acetate was cleared from the plasma with an average MCR of 495 L/day. Norethindrone acetate is rapidly metabolised after an intravenous injection. Norethindrone, the main metabolite, disappears from the plasma with an average half-life of 34.8 hours. Norethindrone maintains a high level compared with norethindrone acetate at all time intervals up to 24 hours and an equilibrium is reached between the two at 24 to 48 hours.
D000085:Acetates / Q000097:blood / Q000378:metabolism; D000328:Adult; D005260:Female; D006207:Half-Life; D006801:Humans; D007700:Kinetics; D008657:Metabolic Clearance Rate; D009640:Norethindrone / Q000097:blood / Q000378:metabolism*; D013997:Time Factors
D000085:Acetates; D009640:Norethindrone