risedronate

Risedronate is a prescription bisphosphonate used to prevent and treat osteoporosis, including postmenopausal osteoporosis and male osteoporosis, and to treat glucocorticoid-induced osteoporosis and, in some settings, Paget's disease of bone. It is available as risedronate sodium and marketed under brand names such as Actonel and Atelvia.

Risedronate works by inhibiting osteoclast-mediated bone resorption. It targets the mevalonate pathway enzyme farnesyl pyrophosphate synthase, reducing osteoclast formation and activity and promoting osteoclast apoptosis, leading to lower bone turnover and, over time, increased bone mineral density.

Indications include osteoporosis in adults (postmenopausal and male), prevention and treatment of glucocorticoid-induced osteoporosis, and Paget's disease of bone (less common). It is not indicated for osteoporosis in children.

Standard tablets are taken orally with a full glass of plain water after an overnight fast, at least 30 minutes before the first food, drink, or other medications; the patient should stay upright for at least 30 minutes. Avoid lying down and avoid calcium- or iron-containing products for at least 2 hours around dosing.

A delayed-release formulation (Atelvia) is taken with breakfast and a glass of plain water, with the patient remaining upright for at least 30 minutes. This form is designed to improve tolerability and absorption in some patients.

Pharmacokinetically, bioavailability is low (about 1% for the standard form); it is not metabolized to a meaningful extent and is excreted unchanged in urine. The drug has a long skeletal half-life due to incorporation into bone.

Contraindications include hypocalcemia, severe renal impairment, pregnancy, and intolerance of bisphosphonates. Common adverse effects are gastrointestinal irritation; esophagitis, gastritis, or ulcers; musculoskeletal pain; and rare osteonecrosis of the jaw or atypical femoral fractures. Interactions include reduced absorption with calcium, antacids, or iron when taken too close to dosing.