Possible Interaction: Levonorgestrel and Progesterone

“It appears from a review of the literature that both oestrogen, progesterone , and non-steriodal anti-inflammatory agents may reduce the number of bleeding days or inhibit acutely the bleeding in women utilizing Norplant.”

“In rats, ethynylestradiol and levonorgestrel (0.030 and 0.125 mg, respectively, subcutaneously) administered daily for 6 weeks reduced the concentrations of pregnenolone (-41%) progesterone (-74%) and allopregnanolone (-79%) in the cerebral cortex; the plasma concentrations of these steroids were also reduced but by smaller extents.”

“The progesterone resistance is counteracted by progestins (Medroxyprogesterone acetate, Dienogest, Danazol, Levonorgestrel ) or by Selective progesterone receptor modulators, a class of drugs under development.”

“The expression of a number of genes was altered on exposure to LNG or LNG and progesterone.”

“Compared to the … group, progesterone levels were significantly … for users of NORPLANT implants during days -12 to -10 (p less than 0.025), -9 to -7 (p less than 0.05), -6 to -4 (p less than 0.0005) and days -3 to -1 (p less than 0.01).”

“Likewise, LNG decreased cerebral cortical levels of allopregnanolone, progesterone and pregnenolone by 75, 68 and 33%, respectively, and hippocampal levels by 55, 65 and 60%, respectively.”

“The results show that serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH) increased, whereas serum estradiol (E2) and progesterone (P4) decreased profoundly after LNG treatment.”

“Thus, the progestin levonorgestrel effectively suppresses follicular and luteal activity in the cat, resulting in a more consistent response to gonadotropin stimulation, even in females prone to spontaneous ovulation.”

“Both levonorgestrel and RU486 enhanced progesterone accumulation in a dose-dependent manner.”

“On the other hand, a dose of 10 microM LNG suppressed the stimulation of progesterone secretion induced by oLH, dibutyryl-cAMP and pregnenolone.”