Objective: Currently, post marketing surveillance (PMS) for prescription-only to over-the-counter (OTC) switched products is conducted based on questionnaires to patients.  These questionnaires appear in the form of postcards and are completed and posted voluntarily by patients.  With such a method, however, it is not possible to select samples randomly and there may be a bias in respondents.  In addition, the response rate of questionnaire postcards tends to be low.  It is not really credible that the efficacy and safety of OTC switches are confirmed by such a method.  An investigation was therefore conducted with the aim of developing an effective method of PMS for OTC switches in order to achieve the intended objective of PMS.
Method and Subjects: Famotidine purchasers were asked to complete a questionnaire form.  The pharmacists asked the subjects to complete the questionnaire form again on their second visit and also checked patient compliance with drug treatment.  The effectiveness of this method was evaluated by reviewing responses to the questionnaire on the first and second visits.
Results and Discussion: It was suggested that the method tested in this investigation may possibly facilitate evaluation of the efficacy of OTC switched products, detection of adverse drug reactions and monitoring of patient compliance with drug treatment.  However, the questionnaire used in the investigation was not suited for detecting symptoms that triggered patients to purchase famotidine.  It was considered necessary to prepare additional questions specifically designed to detect such symptoms.