Pharmacovigilance study of alendronate in England

Alendronate sodium is an aminobiphosphonate, an analog of inorganic pyrophosphate, indicated for the treatment of osteoporosis in post-menopausal women. We analyzed events reported in patients prescribed alendronate by general practitioners (GPs) in England. A non-interventional observational cohort study was conducted using the technique of prescription event monitoring (PEM). Exposure data were obtained from dispensed prescriptions issued between October 1995 and January 1997. Outcome data were obtained by sending questionnaires to prescribing GPs. The cohort comprised 11,916 patients. Events most frequently reported as suspected adverse drug reactions and reason for stopping alendronate were recognized gastrointestinal events listed in the Summary of Product Characteristics. These included nausea/vomiting, abdominal pain, dyspepsia, esophagitis and esophageal reflux. Events with the highest incidence density (ID₁ per 1000 patient months treatment) were dyspeptic conditions (32.2), nausea/vomiting (20.8) and abdominal pain (13.8). The term dyspeptic conditions included dyspepsia, esophagitis, esophageal reflux, duodenitis, gastritis and heartburn. Serious suspected adverse reactions possibly related to alendronate were single reports of angioedema, erythema multiforme, hypercalcemia and hypocalcemia. There were 540 deaths in this elderly cohort. This study suggests that alendronate appears to be well tolerated, though there may be risk of developing gastrointestinal side effects including esophagitis and esophageal ulcers.