Challenge test to bisphosphonates in patients with hypersensitivity reactions to drugs.

BACKGROUND Bisphosphonates are a commonly used class of drugs with known efficacy in the prevention and treatment of postmenopausal and steroid-induced osteoporosis, Paget's disease of bone, hypercaelcemia of malignancy, osteolytic lesions of multiple myeloma, and bone metastases. Nitrogen-containing bisphosphonates have a favourable tolerability and safety profile, cutaneous reactions have been reported. METHODS This is a retrospective case series study, based on the analysis of data from 1429 patients admitted to the Allergy and Clinical Immunology Division of the University of Messina between January 2011 and December 2012. Most patients had previous adverse drug reactions (ADRs) and referred to us for a challenge test with an alternative drug. RESULTS We observed six patients with a past history of adverse drug reaction who needed to be tested for bisphosphonates: three patients for risedronate, two for clodronate and one for alendronate. In two years only two patients were referred to us for an adverse reaction to bisphosphonates: one to alendronate and one to risedronate. Another patient presented a previous reaction to strontium ranelate. The other three patients reported previous hypersensitivity reactions to at least two different classes of drugs. All the patients experienced no reaction using the tested drugs. CONCLUSIONS In our experience drug challenge tests for bisphosphonates are safe and reliable.