PCOS women had elevated baseline allopregnanolone concentrations compared with follicular-phase controls. All overweight women (PCOS and controls) were less sensitive to allopregnanolone than normal-weight controls.

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Rationale: The pharmacokinetics and behavioral effects of isoallopregnanolone (3β-hydoxy-5α-pregnan-20-one) in women are not known.Objectives: Allopregnanolone (3α-hydoxy-5α-pregnan-20-one) is a well known neurosteriod, acting via the GABA A receptor in the human brain. The naturally occurring progesterone metabolite isoallopregnanolone is the 3β-stereoisomer of allopregnanolone. Prior studies have concluded that isoallopregnanolone has no effect on the GABA A receptor. However, an antagonistic effect of isoallopregnanolone to allopregnanolone on the GABA A receptor has been shown in animal and in vitro studies. The purpose of this study was to evaluate the pharmacokinetics and behavioral effects of isoallopregnanolone in humans.Methods: Six healthy women were given three increasing doses of isoallopregnanolone intravenously in the follicular phase. Repeated blood samples for analyses of isoallopregnanolone and allopregnanolone concentrations were drawn. Saccadic eye movement variables, self rated sedation and mood rating scales were used during the test day.A Likert scale for prospective symptoms was used to measure daily fluctuations during the ongoing menstrual cycle.Results: Exogenously administered isoallopregnanolone produced a dose dependent increase in the serum concentration of isoallopregnanolone. In parallel there was also a rise in the allopregnanolone concentration. There was a decrease in saccade eye movement variables, but no effect was found on self-rated sedation or mood and no changes were seen in prospective symptoms during the menstrual cycle.Conclusions: After administration of isoallopregnanolone at a cumulative dose of 0.20 mg/kg, no adverse effects were observed. There is a metabolism of isoallopregnanolone to allopregnanolone, most likely explaining the effects on the saccadic eye movements.3

Allopregnanolone, a GABA-A receptor agonist, decreases gonadotropin levels in women. A preliminary study. Isoallopregnanolone is an isomer to allopregnanolone, but without GABA A receptor effects.The purpose of this study was to investigate effects of allopregnanolone and isoallopregnanolone on gonadotropin levels in healthy women of fertile age. Ten women were given allopregnanolone and five women isoallopregnanolone intravenously in follicular phase. Repeated blood samples were drawn during the test day. Main outcomes were changes in serum levels of FSH, LH, oestradiol and progesterone.Serum-FSH decreased between 5 and 105 minutes after the allopregnanolone injection

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