Surveillance of Over-The-Counter Drugs
The requirements of obtaining and maintaining a marketing authorisation for both prescription only medicines (POM) and non-prescription medicines are laid down in national and international regulations. A marketing authorisation is only issued when a product meets regulatory requirements for safety, efficacy and quality. Extensive evidence of safety is required before POM products are considered for re-classification to Pharmacy Only (P) status (i.e. can only be sold in a pharmacy), and/or subsequently when re-classified to General Sales List (GSL) status. The latter means that patients may purchase a product from any retail outlet and self-medicate without seeking advice from health-care professionals.
Evidence of efficacy and safety for medicines for which a ‘switch’ is proposed, will have been gathered from pre-marketing clinical trials, from post-marketing use and sometimes from comparisons of safety with other products available without prescription. However, each of these methods has limitations regarding monitoring safety and may not predict out-comes in a non-prescription setting. Given the current drive towards self-care, it is important that OTC medicines are subject to safety surveillance in addition to passive spontaneous reporting.
Unfortunately, adverse reactions caused by OTC drugs are less likely to be reported than those associated with POMs. Thus, because of likelihood of under-reporting, spontaneous reporting schemes alone are insufficient to monitor the safety of OTC products and should be complimented by other methods.
The DSRU has repeatedly demonstrated that PEM provides a valuable addition to the pharmacovigilance of POM products in the UK, prescribed by general practitioners in primary care. The DSRU is working in collaboration with other academic centres to develop systematic methodologies for pharmacovigilance studies of non-prescription medicines, based in community pharmacies.