Background and importance There is some controversy about the use of oseltamivir, dose adjustment and treatment duration. A new protocol was updated last year in our hospital specifying renal impairment posology adjustment criteria and cases in which the use of oseltamivir for 7–10 days is justified: patients hospitalised in the intensive care unit (ICU), and patients receiving immunosuppressive or antineoplastics drugs.

Aim and objectives To evaluate the suitability of oseltamivir prescriptions based on the updated protocol in our hospital; to evaluate the pharmacist interventions related to oseltamivir prescriptions; and to analyse the simultaneous prescription of antibiotics in patients with influenza A.

Material and methods This was an observational retrospective study of adult patients with influenza A confirmed infection, treated with oseltamivir during the period December 2018 to February 2019. Paediatric patients and those hospitalised in the ICU were excluded. Demographic variables, unit of prescription, glomerular filtration rate (calculated by CDK-EPI), dosage, treatment duration and reasons to extend oseltamivir treatment were registered. Moreover, pharmaceutical recommendations related to prescription, concomitant use of antibiotics and the results of microbiological culture were gathered.

Results During the study period, 255 patients were included, 132 (52.36%) men and 176 (68.12%) aged >65 years (20–98 years). The units of prescription were: surgical 6.3% and medical 93.7%. Posology was not suitable to renal impairment in 17 cases (6.7%). A total of 42 patients received oseltamivir for a period of time other than 5 days: in 36 patients (85.7%) the reasons were not justified and in 6 patients (14.3%) were due to ICU admission and use of immunosuppressive drugs. Eighty-two pharmaceutical interventions were done: 17 (20.7%) related to posology of which 58.8% were accepted and 65 (79.3) related to the duration of oseltamivir of which 90.8% were accepted. Of all the patients included, 119 (46.9%) were also prescribed an antibiotic, in 31 of whom a microorganism was isolated.

Conclusion and relevance The degree of compliance with the oseltamivir hospital protocol updated in 2018 was >80%. In total, >90% of the pharmaceutical interventions were accepted resulting in a change in the medical prescription according to the protocol recommendations. Pharmaceutical validation adds safety to the hospitalised patient and optimised oseltamivir prescription.

References and/or acknowledgements No conflict of interest.