Background Good Clinical Practice specifies the role of the pharmacist in clinical trials. For each prescription dispensed for a named patient, the pharmacist is responsible for educating the patient on the treatment, counting any residual Investigational Medicinal Product (IMP), and thus for evaluating the compliance.

Purpose To assess the importance of pharmaceutical vigilance about IMPs.

Materials and Methods This prospective study took three months. For each named-patient prescription dispensed, a count of returned treatment (RT) by the patient from the previously dispensed medicines was performed to assess compliance.

Results 117 RTs were analysed. 43 additional RTs from 1 clinical trial were not included in this study due to the impossibility of evaluating compliance (posology changes not notified to the pharmacy and unsuitable secondary packaging). The non-conformity rate was 20% (23 RT). 39% (n = 9) of the non conformities (NC) were due to allowing empty boxes not to be returned. In 61% (n = 14) of NC there was a discrepancy between the expected count of returned IMPs and the one actually made, showing poor compliance.

Average counting time was 12 minutes (5–30 min).

An exact count of returned IMP was operated during dispensing for 34% of returns and after dispensing for 66%. In all cases, a global analysis was performed before the prescription was dispensed.

Conclusions This study points out the major role of the pharmacist in the education of the patient enrolled in clinical trials, about the return of all experimental medicines and the therapeutic schedule. It appeared very important to evaluate compliance while the pharmacist was dispensing the next prescription, independently of the time consumed, in order to correct possible errors in taking the medicines at that time.

No conflict of interest.