Comparative Pharmacology
Head-to-head clinical analysis: NORETHINDRONE AND ETHINYL ESTRADIOL 7 14 versus NORGESTIMATE ETHINYL ESTRADIOL.
Peer-Reviewed Evidence
Head-to-head clinical analysis: NORETHINDRONE AND ETHINYL ESTRADIOL 7 14 versus NORGESTIMATE ETHINYL ESTRADIOL.
NORETHINDRONE AND ETHINYL ESTRADIOL (7/14) vs NORGESTIMATE; ETHINYL ESTRADIOL
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.
Combination oral contraceptive containing norgestimate (a progestin) and ethinyl estradiol (an estrogen). The primary mechanism is suppression of gonadotropins (FSH and LH) via negative feedback on the hypothalamic-pituitary-ovarian axis, preventing ovulation. Additional effects include thickening cervical mucus (inhibiting sperm penetration) and altering endometrial receptivity.
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, one tablet daily at the same time for 21 days, followed by 7 placebo tablets.
None Documented
None Documented
Norethindrone: 8-11 hours; Ethinyl estradiol: 17-27 hours. Achieves steady state within 5-10 days, permitting once-daily dosing.
Norgestimate: terminal half-life of norelgestromin (active metabolite) is 27.6 ± 7.8 hours; ethinyl estradiol: terminal half-life is 17.5 ± 6.3 hours. Steady state achieved within 14 days.
Norethindrone: ~50% renal, ~50% fecal; Ethinyl estradiol: ~50% renal, ~50% fecal, with enterohepatic circulation.
Norgestimate metabolites are primarily excreted via urine (60-80%) and feces (35-49%) as glucuronide and sulfate conjugates; ethinyl estradiol is excreted in urine (40%) and feces (60%) as conjugates.
Category D/X
Category D/X
Progestin
Progestin + Estrogen