Milk and plasma concentrations of the progestin ST-1435 in women treated parenterally with ST-1435

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


      A subcutaneous contraceptive capsule releasing progestin ST-1435 was used by 6 breast-feeding women. One to three paired milk and plasma samples were collected over a one-month period and the concentrations of ST-1435 were determined by radioimmunoassay.
      An improved and sensitive method for determination of ST-1435 in milk was developed. A column chromatographic purification of milk prior to radioimmunoassay decreased the blank and improved sensitivity.
      The average plasma concentration of ST-1435 was 62 ± 20 pg/ml (mean ± SD). The average milk concentration of ST-1435 was 38 pg/ml (ranging from 7 to 73 pg/ml), while the average milk to plasma ratio was 0.60 (ranging from 0.25 to 0.91). There was a significant correlation between ST-1435 concentrations in breast milk and plasma, indicating that the concentration in plasma is the major determinant for the amount of ST-1435 excreted into milk. Since studies with this drug have shown good contraceptive efficacy and low bioavailability after oral intake, ST-1435 is a good candidate for lactational contraception.
      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


      1. Editorial.
        in: International Conference on better health for women and children through family planning: recommendations for action. Stud in Fam Plann. 19. 1988: 58-60
        • Nilsson S
        • Nygren K-G
        • Johansson EDB
        D-norgestrel concentrations in maternal plasma, milk and child plasma during administration of oral contraceptives to nursing women.
        Am J Obstet Gynecol. 1977; 129: 178-184
        • Koetsawang S
        • Nukulkarn P
        • Fotherby K
        • Shrimanker K
        • Mangalam M
        • Torvobola K
        Transfer of contraceptive steroids in milk of women using long-lasting gestagens.
        Contraception. 1982; 25: 321-331
        • Lähteenmäki PLA
        Intestinal absorption of ST-1435 in rats.
        Contraception. 1984; 30: 143-151
        • Coutinho E
        • DaSilva AR
        • Kraft H-G
        Fertility control with subdermal Silastic capsules containing a new progestin (ST-1435).
        Int J Fertil. 1976; 21: 103-108
        • Lähteenmäki P
        • Weiner E
        • Lähteenmäki P
        • Johansson E
        • Luukkainen T
        Contraception with subcutaneous capsules containing ST-1435.
        Contraception. 1981; 23: 63-75
        • Lähteenmäki P
        • Weiner E
        • Lähteenmäki P
        • Johansson EDB
        • Luukkainen T
        Pituitary and ovarian function during contraception with one subcutaneous implant releasing a progestin, ST-1435.
        Contraception. 1984; 29: 299-306
        • Kurunmäki H
        • Toivonen J
        • Lähteenmäki PLA
        • Luukkainen T
        Intracervical release of ST-1435 for contraception.
        Contraception. 1984; 29: 411-421
        • Lähteenmäki PLA
        • Lähteenmäki P
        Concentration-dependent mechanisms of ovulation inhibition by the progestin ST-1435.
        Fertil Steril. 1985; 44: 20-24
        • Kurunmaki H
        • Toivonen J
        • Lähteenmäki PLA
        • Luukkainen T
        Contraception with subdermal ST-1435 capsules: side-effects, endocrine profiles and liver function related to different lengths of capsules.
        Contraception. 1985; 31: 305-318
        • Lithell H
        • Åhren T
        • Odlind V
        • et al.
        Effects of progestins on lipoprotein patterns.
        in: Bardin CW Milgrom E Mauvais-Jarvis P Progesterone and progestins. Raven Press, New York1983: 421-432
        • Lähteenmäki PLA
        • Hammond GL
        Serum non-protein bound percentage and distribution of the progestin ST-1435: no effect of ST-1435 treatment on plasma SHBG and CBG binding capacities.
        Acta Endocrinologica (Kbh.). 1983; 102: 307-313
        • Lähteenmäki PLA
        Contraceptive action of a synthetic progestin, ST-1435.
        in: Academic Dissertation. University of Helsinki, Helsinki, Finland1986
        • Carr BR
        • Mikhail G
        • Flickinger GL
        Column chromatography of steroids on Sephadex LH-20.
        J Clin Endocrinol. 1971; 33: 358-360
        • Heikkilä M
        • Haukkamaa M
        • Luukkainen T
        Levonorgestrel in milk and plasma of breast-feeding women with a levonorgestrel-releasing IUD.
        Contraception. 1982; 25: 41-49
        • Hammond GL
        • Lähteenmäki PLA
        • Lahteenmaki P
        • Luukkainen T
        Distribution and percentages of non-protein bound contraceptive steroids in human serum.
        J Steroid Biochem. 1982; 17: 375-380