Surveillance of a recently switched non-prescription medicine (Diclofenac) using a pharmacy-based approach

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Abstract
Purpose Postmarketing surveillance of prescription medicines is a routine practice, yet similar evaluation of non‐prescription medicines, including those recently switched from prescription status, is uncommon. This study presents the methodologic issues and limitations of the use of pharmacies in the ‘post‐reclassification’ surveillance of oral diclofenac potassium 25 mg which had been recently switched from physician prescription to non‐prescription sale. Methods Consenting user‐purchasers were recruited from 175 New Zealand pharmacies over 4 months. Purchasers were mailed a questionnaire for completion 7 days post‐purchase. Those purchasers who met criteria for being potentially ‘at risk’ of adverse events were re‐surveyed 30 days post‐purchase. A descriptive analysis was carried out using t‐test and chi‐square as appropriate. These results were compared to those from other types of studies in this area. Results The 1240 recruited purchasers returned 990 valid questionnaires (80% response). Of these 557 (56%) met ‘at risk’ criteria and received the second questionnaire with 480 valid returns (86.2% response). Conclusions Useful data was gathered on the ‘real‐life’ usage of a medicine recently reclassified from prescription to non‐prescription sale. The use of community pharmacies as recruiting centres was found to be effective. Copyright © 2000 John Wiley & Sons, Ltd.