Actonel osteoporosis drug. Actonel (risedronate sodium) tablet with its packaging. This drug is used to treat and prevent osteoporosis in post- menopausal women. It belongs to a class of drugs called bisphosphonates. It inhibits the action of bone cells that degrade and reabsorb bone (osteoclasts), therefore slowing the loss of bone mass. One tablet is taken once a week. It is important to take actonel while upright and with plenty of water as it can cause inflammation and ulceration of the oesophagus.