Short answer: Estradiol/Norethindrone Acetate has a half-life of estradiol 12 to 14 hours; norethindrone 8 to 11 hours. Levels peak estradiol 5 to 8 hours; norethindrone 0.5 to 1.5 hours after a dose. People vary, so treat these as estimates.
Activella combines estradiol, the main estrogen, with norethindrone acetate, a progestin, in one daily tablet for women with a uterus after menopause. The progestin lowers the risk of uterine lining overgrowth from estrogen. It is sold as Activella.
Also known as: Activella, norethindrone acetate.
Activella comes as 1 mg estradiol/0.5 mg norethindrone acetate and 0.5 mg/0.1 mg tablets, 28 to a blister pack, taken every day with no break.
The Activella label approves it for moderate to severe hot flashes and vaginal atrophy due to menopause, and to prevent osteoporosis after menopause. Label dosing is one tablet a day: either strength for hot flashes and bone, and the 1 mg/0.5 mg strength for vaginal atrophy. For vaginal symptoms alone the label says to consider vaginal products first, and for bone alone, non-estrogen drugs first.
Its boxed warning is titled "Cardiovascular disorders, probable dementia, breast cancer, and endometrial cancer", based on the Women's Health Initiative. In November 2025 FDA said it is starting to remove the boxed warnings about heart disease, breast cancer and probable dementia from menopause hormone products, but not the endometrial cancer warning for systemic estrogen-alone products. The label version we read still carries the full boxed warning. Breast pain was 24% on 1 mg/0.5 mg in the 12-month study, and vaginal bleeding was 26% vs 12% on placebo on 0.5 mg/0.1 mg. Full numbers are on the Activella side effects and Activella dosing schedule pages. Comparisons: Prempro vs Activella and Fyavolv vs Activella. Storage: Activella.
The Activella label says estradiol peaks 5 to 8 hours after a tablet and norethindrone 0.5 to 1.5 hours after. The estradiol half-life after one 1 mg/0.5 mg tablet is 12 to 14 hours, and the terminal half-life of norethindrone is about 8 to 11 hours.
Numbers shown are taken from the source above. Half-life varies from person to person.
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