Short answer: Prempro and Activella are both one-a-day tablets that pair an estrogen with a progestin.12 Prempro uses conjugated estrogens with medroxyprogesterone acetate; Activella uses estradiol with norethindrone acetate. Both are approved for hot flashes, vaginal atrophy and preventing osteoporosis after menopause, and both carry a boxed warning. Neither label reports a trial against the other.
| Prempro | Activella | |
|---|---|---|
| Ingredients | Conjugated estrogens + medroxyprogesterone acetate1 | Estradiol + norethindrone acetate2 |
| Strengths | Four, from 0.3 mg/1.5 mg to 0.625 mg/5 mg1 | 1 mg/0.5 mg and 0.5 mg/0.1 mg2 |
| Schedule | One tablet daily; Premphase is a 28-day pack with estrogen alone on days 1 to 141 | One tablet daily2 |
| Approved for | Hot flashes, vulvar and vaginal atrophy, and preventing osteoporosis after menopause1 | Hot flashes, vulvar and vaginal atrophy, and preventing osteoporosis after menopause2 |
| Side effects in label trials | Breast pain 26% on 0.625 mg/2.5 mg vs 8% on placebo (1 year)1 | Breast pain 21% vs 0% on placebo (3-month study, 1 mg/0.5 mg)2 |
| Boxed warning | Blood clots, stroke, heart attack, breast cancer, endometrial cancer, probable dementia1 | Blood clots, stroke, heart attack, breast cancer, endometrial cancer, probable dementia2 |
| Missed dose | Take as soon as possible unless the next dose is near (Patient Information)1 | No rule in the label2 |
The ingredients. Prempro's estrogen is conjugated estrogens, the same as in Premarin, and its progestin is medroxyprogesterone acetate.1 Activella's estrogen is estradiol and its progestin is norethindrone acetate.2 Premphase, sold under the same label as Prempro, gives estrogen alone for the first 14 days of each 28-day pack and both hormones for the last 14.1
The boxed warnings cover the same risks, based on the Women's Health Initiative studies.12 Breast pain is a leading side effect in both labels.12 These numbers come from separate trials with different people, lengths and methods, so they are not a head-to-head comparison. For vaginal symptoms alone, the Activella label says vaginal products are considered first.2
Which tablet and strength fits is for your prescriber. More detail: Prempro side effects, Activella side effects, the Prempro and Activella dosing schedules, and the Prempro missed-dose page.