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

Area of Science:

• Dermatology
• Pharmacology
• Immunology

Background:

• Cutaneous adverse drug reactions (CADRs) associated with bisphosphonates (BPs) are infrequently documented.
• Limited literature exists on the diagnostic efficacy of cutaneous provocation tests for BP-induced CADRs.

Purpose of the Study:

• To assess the diagnostic utility and limitations of cutaneous provocation tests for bisphosphonate-induced CADRs.
• To provide insights into the interpretation of patch and intradermal tests for bisphosphonate hypersensitivity.

Main Methods:

• A descriptive case series of patients with CADRs due to bisphosphonates.
• Utilized patch testing and intradermal testing between 2005 and 2010.
• Included a control group for comparison.

Main Results:

• Positive patch test reactions (D4) observed with alendronate and ibandronate at varying concentrations and vehicles.
• Positive intradermal test reactions (D3) noted with alendronate and ibandronate.
• Specific reaction grading (e.g., D4++, D3+++) documented for individual patients and drugs.

Conclusions:

• Interpreting patch test reactions for bisphosphonate CADRs is challenging.
• High drug concentrations may induce irritant reactions, not true hypersensitivity.
• Low drug concentrations risk false-negative results, complicating diagnosis.