Fosamax is a bisphosphonate drug used for osteoporosis and several other bone diseases. It is marketed alone as well as in combination with vitamin D under the name Fosavance.

Side-effects GI tract: most prominent are harmless side effects such as mild nausea, dyspepsia, abdominal cramps, flatulence, diarrhea, or obstipation. A severe side effect is an ulceration of the esophagus caused by alendronate, which may require hospitalization and intensive treatment. Gastric and duodenal ulceration.

General: infrequent cases of skin rash, rarely manifesting as Stevens-Johnson syndrome and toxic epidermal necrolysis, eye problems (uveitis, scleritis) and generalized muscle, joint, and bone pain (rarely severe) have been seen. In laboratory tests decreased calcium and phosphate values may be obtained but reflect action of the drug and are harmless.

Osteonecrosis of the jaw, a recognised side-effect of bisphosphonates.

Dosage Prophylaxis of osteoporosis in women: 5-10mg daily or 35-70mg weekly.

Therapy of osteoporosis in women and men : 10mg daily or 70mg weekly.

Osteoporosis under corticosteroids: 5mg daily or 35mg weekly in men and premenopausal women or those receiving concomitant HRT. In postmenopausal women not receiving HRT the recommended dose is 10mg daily or 70mg weekly.

Paget's Disease: 40mg daily for 6 months.

The drug is to be taken only upon rising for the day with plenty of water. Stand, walk or sit 30 minutes afterwards to avoid esophageal damage. At least 30 minutes should be waited before meals or other beverages than water are taken in.

Interactions Milk, diet and drugs containing high amounts of calcium, magnesium or aluminium (antacids): the resorption of alendronate is decreased. At least half an hour should pass after intake of alendronate before taking the supplement or drug.

Highly active vitamin D analogues or fluorides: no data is available. Concomitant treatment should be avoided.

The additional beneficial effect of HRT (hormone replacement therapy) with estrogens/progestins or raloxifene in postmenopausal women remains to be elucidated, but no interactions have been seen. The combination is therefore possible.

Intravenous ranitidine increases the oral bioavailability of alendronate. No clinical consequences are known.

The combination of NSAIDS and alendroate increases the risk of gastric ulcers. Both these drugs have the potential to irritate the upper gastro-intestinal mucosa.

Does Merck have a patent on this drug?

Yes, but the patent is set to expire in 2008 and Merck has lost a series of appeals to block a generic version of the drug from being certified by the US FDA.

Disclaimer: The information presented here should not be interpreted as or substituted for medical advice. Please talk to your doctor to learn more about Fosamax.