Safety and usage pattern of low-dose diclofenac when used as an over-the-counter medication: results of an observational cohort study in a community-based pharmacy setting.

OBJECTIVE: The widespread and unsupervised nature of nonprescription drug usage makes it important that evidence of effectiveness and safety should be gathered in a real-world, over-the-counter (OTC) setting. This study was designed to evaluate the "real life" behavior of consumers with nonprescription access to low-dose diclofenac-K, with special focus on tolerability and the pattern of product usage. PARTICIPANTS AND METHODS: Participants were recruited from consumers presenting at 62 community-based pharmacies in Norway after they had purchased low-dose diclofenac-K. Baseline data were collected from the participants in the pharmacy and information on diclofenac usage, the condition for which it was used, comprehensibility of the package insert, efficacy and safety were collected 5 days after commencing the medication. Follow-up safety data were collected 19 days after commencing study medication.
RESULTS: 446 individuals participated in the study with 383 taking medication and completing questionnaires at each time point. The directions for use were followed well with regard to recommended indications, contraindications and maximum dosages, but less well with respect to the recommended duration of use and concurrent medications. Most participants reported complete relief, a lot of relief, fair relief or some relief from the symptoms from which they were suffering and 70% were willing to purchase diclofenac-K again. Only 6.5% of participants reported adverse events and 6 participants (1.6%) were considered to have experienced a drug-related adverse event, none of which was considered to be severe.
CONCLUSIONS: Overall, this study showed that low-dose diclofenac-K is efficacious, safe and commonly used in accordance with the directions for use when used as an OTC medication. It also demonstrated that the use of an OTC analgesic medication can be successfully monitored in a pharmacy-based cohort study.