Medicine-use evaluation of doxazosin prescribing to inform formulary recommendations

It is estimated that >50% of all medicines are inappropriately prescribed, dispensed or sold. In 2018, the Western Cape Government Health (WCGH) Provincial Pharmacy and Therapeutics Committee (PPTC) endorsed an investigation of doxazosin use in provincial public sector healthcare facilities using a medicine-use evaluation (MUE). This was based on potential inappropriate prescribing, high usage and high costs associated with doxazosin.

To determine whether doxazosin was being prescribed in accordance with recommendations from standard treatment guidelines and essential medicines lists for hospital and primary healthcare level, as well as from the WCGH provincial code list.

The study design consisted of a retrospective multicentre prescription review. The study population included all adult outpatients who were prescribed doxazosin, which was to be dispensed by the WCGH Chronic Dispensing Unit. Criteria for evaluation included indications for doxazosin administration and total daily dose prescribed.

The study sample comprised 171 patients. The main indication for doxazosin administration was as a fourth-line agent for the treatment of hypertension (82%). The remaining indications were not guideline approved (18%). The total daily doses identified were 4 mg (62%), followed by 8 mg (36%) and 2 mg (2%). All of these were approved dosages as per guideline recommendations.

MUEs are an untapped resource for medication-use monitoring and practice improvement. MUEs offer a distinct, cost-effective approach to improve medicine use in all settings. This MUE revealed a relatively minor concern with doxazosin prescribing. MUEs can be beneficial to inform formulary changes and re-evaluate medication-use restrictions.