5OH-DF

Diclofenac (DF) is one of the most popular drugs world-wide belonging to the family of nonsteroidal antiinflammatory drugs (NSAIDs). Adverse drug reactions (ADRs), which occur in about every fifth patient, are well-known side effects mainly caused by the NSAIDs' acidic properties. More serious are drug hypersensitivity reactions (DHRs) to DF, which clinically manifest as Type-I-like allergic reactions with sudden and unpredictable occurrence and can progress into anaphylactic shock. Two pathomechanisms are currently thought to be involved in NSAIDs hypersensitivity reactions: (i) multiple NSAIDs hypersensitivity (also those involving DF) has been considered as pharmacokinetic disorders due to non-selective coinhibition of cyclooxygenase (COX)-1 leading to shifts in the prostaglandin and leukotriene levels; (ii) in contrast, for selective NSAID hypersensitivities including DF, an involvement of the immune system is still being postulated.