Bisphosphonate-induced cutaneous adverse events: the difficulty of assessing imputability through patch testing.

ABSTRACT

BACKGROUND: Cutaneous adverse drug reactions (CADRs) due to bisphosphonates (BPs) have been scarcely described in the literature. OBJECTIVE: To discuss the diagnostic value and limitations of cutaneous provocation tests with BPs. METHODS: A descriptive case series study with a control group of CADRs due to BPs studied using patch testing from 2005 to 2010 is presented. RESULTS: Patient 1 showed a positive D4++ with alendronate at 1% in petrolatum and D4+++ with alendronate at 1 and 0.1% in water. Patient 2 showed a positive intradermal test D3++ with alendronate at 0.1% in water. Patient 3 showed a positive patch test D4+ with ibandronate at 1% in petrolatum and D4++ with ibandronate at 1% in water, and a positive intradermal test D3+++ with ibandronate at 0.1% in water. CONCLUSION: Establishing a correct interpretation of a patch test reaction is difficult based just on cutaneous test results. Too high concentrations of the drug can cause irritation and too low concentrations can be responsible of false-negative test reactions.