Comparative Pharmacology
Head-to-head clinical analysis: NORETHINDRONE AND ETHINYL ESTRADIOL 7 14 versus PROVERA.
Peer-Reviewed Evidence
Head-to-head clinical analysis: NORETHINDRONE AND ETHINYL ESTRADIOL 7 14 versus PROVERA.
NORETHINDRONE AND ETHINYL ESTRADIOL (7/14) vs PROVERA
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Norethindrone is a progestin that suppresses gonadotropin release, preventing ovulation. Ethinyl estradiol is an estrogen that provides negative feedback on the hypothalamic-pituitary axis, further inhibiting ovulation. The combination also alters cervical mucus and endometrial lining to impede fertilization and implantation.
Provera (medroxyprogesterone acetate) is a progestin that binds to progesterone receptors, suppressing gonadotropin secretion, inhibiting endometrial growth, and inducing secretory changes in the endometrium. It also has antigonadotropic effects by reducing LH and FSH release from the pituitary.
One tablet (norethindrone 0.5 mg/ethinyl estradiol 35 mcg) orally once daily for 21 days (7 active tablets of norethindrone 0.5 mg/ethinyl estradiol 35 mcg followed by 14 active tablets of norethindrone 1 mg/ethinyl estradiol 35 mcg). Start on day 1 of menstrual cycle.
Oral: 5-10 mg daily for 5-10 days for secondary amenorrhea; 5-10 mg daily for 12-14 days per cycle in combination with estrogen for endometrial hyperplasia; 400-1000 mg/day IM monthly for endometriosis.
None Documented
None Documented
Norethindrone: 8-11 hours; Ethinyl estradiol: 17-27 hours. Achieves steady state within 5-10 days, permitting once-daily dosing.
Terminal elimination half-life is approximately 12-17 hours for medroxyprogesterone acetate (oral). With depot intramuscular injection, the half-life is extended to approximately 50 days due to slow absorption from the injection site.
Norethindrone: ~50% renal, ~50% fecal; Ethinyl estradiol: ~50% renal, ~50% fecal, with enterohepatic circulation.
Renal (50-60% as metabolites), biliary/fecal (30-40%). Less than 1% excreted unchanged.
Category D/X
Category C
Progestin
Progestin