Short answer: Risedronate has a half-life of about 561 hours (terminal). Levels peak about 1 hour after a dose. People vary, so treat these as estimates.
Risedronate is a bisphosphonate, a drug that binds to bone and slows the cells that break bone down. It is sold as Actonel (immediate-release tablets taken on an empty stomach) and Atelvia (a delayed-release tablet taken right after breakfast), both by Allergan, and as generic tablets, for osteoporosis and Paget's disease of bone.
Also known as: Actonel, Atelvia, risedronate sodium.
Actonel comes as 5 mg (daily), 35 mg (weekly), 75 mg (two days in a row each month) and 150 mg (monthly) tablets. Atelvia is a 35 mg delayed-release tablet taken once a week.
The Actonel label approves risedronate to treat and prevent osteoporosis in women after menopause, to build bone in men with osteoporosis, to treat and prevent steroid-caused osteoporosis, and to treat Paget's disease of bone. For osteoporosis after menopause it lists four schedules: 5 mg daily, 35 mg weekly, 75 mg on two days in a row each month, or 150 mg monthly; men take 35 mg weekly. Actonel is swallowed whole with 6 to 8 ounces of plain water at least 30 minutes before the first food, drink or other medicine of the day, without lying down for 30 minutes. Atelvia, approved for osteoporosis after menopause, is the opposite: 35 mg once a week taken right after breakfast with at least 4 ounces of water. Both labels say the best length of use is not known, and people at low fracture risk may be considered for stopping after 3 to 5 years.
The labels have no boxed warning. Warnings cover irritation and ulcers of the esophagus, low calcium, jaw bone death, unusual thigh fractures and severe bone, joint or muscle pain. Actonel and Atelvia are the same drug and are not taken together. In the 3-year Actonel trials, back pain was 28.0% on 5 mg vs 26.1% on placebo. Full numbers are on the Actonel side effects, Actonel dosing schedule, missed Actonel dose, Atelvia side effects, Atelvia dosing schedule and missed Atelvia dose pages. Comparisons: Atelvia vs Actonel, Fosamax vs Actonel and Atelvia vs Fosamax. Storage: bone tablets and Atelvia.
The Actonel label says peak absorption comes about 1 hour after an oral dose, along the upper gut. In women after menopause with low bone mass, the terminal half-life was 561 hours, because risedronate binds to bone and is released slowly.
Numbers shown are taken from the source above. Half-life varies from person to person.
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