How 'fast' is over-the-counter (OTC) pain relief?

Abstract

Background The onset of action of OTC analgesics compared to placebo is generally detected by 30 minutes in clinical trials. Based on their experience with OTC analgesics, consumers may have a different understanding of “onset” and which time span is “fast.” Therefore, we asked them. Methods We used our piloted questionnaire1 to interview a convenience sample of 170 consecutive adults (ca. the same number selected for a clinical trial) who had a history of using an OTC analgesic drug to treat non-specific non-daily headaches (the main use of OTC analgesics). We asked them questions about when a pain-relieving tablet medicine is “beginning to work for your headache.” Results Approximately 40% considered onset within 15 minutes indicative of working “fast” to relieve headache, 89% within 30 minutes (median and mode: 20 minutes). It would take a difference of at least 5 minutes for most of them to say that one drug begins to provide relief “faster” than another drug; ca. 70% reported a requisite difference of at least 10 minutes. Conclusions These findings indicate, reassuringly, that consumers' understanding of an OTC drug's onset of action for headache coincides with the pharmacodynamic properties of OTC analgesics observed in clinical trials. They suggest that “patient-determined” criteria like these (for onset of action) may enhance our ability as investigators to measure and interpret patients' responses in clinical trials. Clinical Pharmacology & Therapeutics (2005) 77, P52–P52; doi: 10.1016/j.clpt.2004.12.090