Clearance of levonorgestrel from the circulation following removal of NORPLANTR subdermal implants

      This paper is only available as a PDF. To read, Please Download here.


      The disappearance of levonorgestrel from plasma after the removal of NORPLANTR subdermal implants was studied in 12 women who had been treated from 5.5 to 78 months. The existence of one or two half-lives for the rate of disappearance was assessed. The influence of body weight, body fat and length of treatment upon levonorgestrel clearance was studied through stepwise regression analysis.
      It was found that the levonorgestrel decay rate after implant removal can be entirely accounted assuming one half-life of Math Eq. Stepwise regression analysis showed that levonorgestrel half-life is positively correlated with body weight and not significantly correlated with the length of treatment or body fat. It is concluded that, after long-term administration of levonorgestrel via subdermal implants, the major part of the steroid is cleared from plasma within 96 h and that only trace amounts are detected in the following days.
      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Contraception
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Hendeles SM.
        • Galand N
        • Schwers J
        Metabolism of orally administered d-norgestrel in women.
        Acta Endocrinol. 1972; 71: 557-568
        • Littleton P
        • Fotherby K
        • Dennis KJ
        Metabolism of (14C)-norgestrel in man.
        J Endocrinol. 1978; 42: 591-598
        • Wang E
        • Shi S
        • Cekan SZ
        • Landgren B-M
        • Diczfalusy E
        Hormonal consequences of “Missing the Pill”.
        Contraception. 1982; 26: 545-566
        • Warren RJ
        • Fotherby K
        Radioimmunoassay of synthetic progestagens, norethisterone and norgestrel.
        J Endocrinol. 1974; 62: 605-618
        • Warren RJ
        • Fotherby K
        Metabolism of d- and l-norgestrel in humans.
        Arzneim-Forsch (Drug Res). 1975; 25: 964-965
        • Uniyal JP
        • Buckshee K
        • Sharma U
        • Laumas KR
        Disappearance of (14,15-3H)-d,l-norgestrel from plasma and its distribution in the reproductive tract of women.
        Acta Endocrinol. 1976; 82: 851-864
        • Weiner E
        • Victor A
        • Johansson EDB
        Plasma levels of d-norgestrel after oral administration.
        Contraception. 1976; 14: 563-570
        • Olsson SE
        • Odlind V
        • Johansson EDB
        • Nordstrom MD
        Plasma levels of levonorgestrel and free levonorgestrel index in women using NORPLANTR implants or two covered rods (NORPLANTR-2).
        Contraception. 1987; 35: 215-228
        • Croxatto HB
        • Díaz S
        • Miranda P
        • Elamsson K
        • Johansson EDB
        Plasma levels of levonorgestrel in women during long-term use of NORPLANTR.
        Contraception. 1981; 23: 197-209
        • Sokal RR
        • Rohlf FJ
        2nd ed. WH Freeman and Co, San Francisco1981
        • Díaz S
        • Pavez M
        • Cárdenas H
        • Croxatto HB
        Recovery of fertility and outcome of planned pregnancies after the removal of NORPLANTR.
        Contraception. 1987; 35: 569-579
        • Thau R
        • Lanman JT
        Metabolic clearance rates (MCR) and production rates (PR) of plasma progesterone in pregnant and pseudopregnant rabbits.
        Endocrinology. 1975; 97: 454-457