Background Gliclazide is a sulfonylurea administrated as a single daily dose according to the data sheet. Intake of this drug several times a day could increase the occurrence of hypoglycaemia.

Purpose To evaluate the impact of an intervention developed by the pharmacy department to correct dosages of gliclazide that consisted of more than a single daily dose and therefore were not safe.

Material and methods A prospective study comparing the number of non-recommended dosages of gliclazide before and after our intervention was conducted. Field of study: two tertiary hospitals and their reference areas (the population consisted of 666 000 people). In August 2015, our department searched for patients with non-safe gliclazide prescriptions. These patients were included in lists which were sent as feedback to their corresponding physicians, along with a reminder of the correct dosage for this medical product. In December 2015, gliclazide prescriptions were studied in the same group of patients to analyse whether those non-recommended dosages had been corrected. Data were obtained from prescriptions under the National Health System coverage.

Results The average age of patients was 70.5 years and 51.7% were men. In the first time point (August 2015), the number of patients with gliclazide prescriptions were 7856. 18% (1412) of the prescriptions were unsafe. Dosages found were: every 3 hours (1); every 6 hours (20); every 8 hours (420); and every 12 hours (970). In the second time point (December 2015), from 1412 patients with inadequate dosages, 1256 (88.9%) continued with an active gliclazide prescription. The dosage was corrected in 730 of the initial 1256 patients (58.1%). The number of modified dosage regimens was 751, however 21 of these changes consisted of unsafe prescriptions (more than a single daily dose): every 6 hours (2); every 8 hours (9); and every 12 hours (10).

Conclusion Our intervention appeared to be an effective method to correct the lack of information that can foster incorrect prescriptions of gliclazide. However, we plan to perform another intervention to try to correct other unsafe prescriptions.

No conflict of interest