Patterns of interchange in the dispensing of non-steroidal anti-inflammatory drugs.

Patterns of change in dispensings of non-steroidal anti-inflammatory drugs (NSAID) were evaluated from the pharmacy records of a health maintenance organization (HMO). Overall, 52.8% of NSAID prescriptions were followed by another NSAID prescription within 60 days. Among patients for whom NSAIDs were dispensed twice within 60 days, 15% received a different NSAID. Switching between NSAIDs was more frequent in younger age groups; there was no difference between males and females. Chronic and non-chronic indications for NSAID use were associated with similar probabilities of switches between drugs among repeat users. NSAIDs that were frequently switched to for lack of efficacy or for prior toxicity of other NSAIDs were not as a whole themselves associated with more frequent switches for the same reasons.