The gastrointestinal tolerability and safety of oral bisphosphonates

Oral bisphosphonates are effective for osteoporosis and other hyperresorptive bone disorders. Although well-tolerated in efficacy trials, some oral aminobisphosphonates have been associated with upper gastrointestinal intolerance and injury in postmarketing experience. Clinical trials often underestimate the rate of adverse events in clinical practice, and ethics prohibit direct evaluation of toxicity in high-risk patients. Accordingly, animal models and endoscopy studies of oral bisphosphonates provide valuable insight. It is unclear whether variation in ulcerogenic potential reflects differences in dosing, formulation or chemical structure. Furthermore, the clinical relevance of endoscopic lesions is uncertain. Ongoing postmarketing review will determine whether differences in endoscopic damage predict tolerability and safety in clinical practice. However, physicians and patients should consider risk factors for oesophageal injury when initiating therapy.