Short answer: Fosamax (alendronate) and Actonel (risedronate) are bisphosphonate tablets for osteoporosis, both taken with plain water at least 30 minutes before food while staying upright.12 Fosamax is 70 mg weekly or 10 mg daily. Actonel adds monthly options: 75 mg on two days in a row or 150 mg once. Neither label reports a trial against the other.
| Fosamax (alendronate) | Actonel (risedronate) | |
|---|---|---|
| Approved for | Treat and prevent postmenopausal osteoporosis; men with osteoporosis; steroid-induced osteoporosis; Paget's disease1 | Treat and prevent postmenopausal osteoporosis; men with osteoporosis; treat and prevent steroid-induced osteoporosis; Paget's disease2 |
| Osteoporosis schedules | 70 mg once a week or 10 mg once a day1 | 5 mg daily, 35 mg weekly, 75 mg on two days in a row each month, or 150 mg monthly; men 35 mg weekly2 |
| How to take | On getting up, 6 to 8 oz plain water, at least 30 minutes before food, drink or other medicine; stay upright 30 minutes1 | Swallowed whole with 6 to 8 oz plain water at least 30 minutes before food or drink; stay upright 30 minutes2 |
| Side effects in label trials | Abdominal pain 6.6% vs 4.8% on placebo; musculoskeletal pain 4.1% vs 2.5% (3-year trials, drug-related)1 | Back pain 28.0% vs 26.1%; abdominal pain 12.2% vs 9.9% (3-year trials, all events)2 |
| Main warnings | Esophagus irritation, low calcium, jaw bone death, unusual thigh fractures1 | Esophagus irritation, low calcium, jaw bone death, unusual thigh fractures2 |
| Boxed warning | None1 | None2 |
| How long | Best length not set; low-risk people may be considered for stopping after 3 to 5 years1 | Best length not set; same 3 to 5 year review2 |
The schedule. Fosamax is a weekly 70 mg tablet (or 10 mg daily); the label notes only the 70 mg tablet is still sold as Fosamax.1 Actonel has four schedules for postmenopausal osteoporosis, including two monthly ones: 75 mg taken on two days in a row, or a single 150 mg tablet.2 The morning routine is the same for both: plain water only, an empty stomach, and no lying down for 30 minutes.12
The two labels count side effects differently. Fosamax's main table lists only events investigators judged possibly related to the drug: abdominal pain 6.6% vs 4.8% on placebo.1 Actonel's lists all reported events, so the numbers look larger on both arms: back pain 28.0% vs 26.1%, abdominal pain 12.2% vs 9.9%.2 These numbers come from separate trials with different people, lengths and methods, so they are not a head-to-head comparison. The warnings are the same set for both.
Which tablet and schedule fits is for your prescriber. More detail: Fosamax side effects, Actonel side effects, the Fosamax and Actonel dosing schedules, and the Fosamax and Actonel missed-dose pages.