'You look like a 240 mg': Gentamicin dosing at a Sydney hospital

Abstract

Background: Gentamicin, an aminoglycoside antibiotic, is used to treat gram-negative bacterial infections. In the current Therapeutic Guidelines: Antibiotic, the recommendations for gentamicin have changed, i.e. the initial dose for empirical treatment, subsequent dose calculations and maximum duration of therapy. Aim: To investigate the pattern of gentamicin utilisation and adherence to local gentamicin dosing guidelines. Method: A cross-sectional audit was conducted of available medication charts for inpatients (n = 51) administered gentamicin at a Sydney hospital over a 2 month period. For comparison, patients were stratified according to age into younger (18 to 59 years) or older (≥ 60 years) groups. Results: Of the 51 patients evaluated, only 11 (8 younger, 3 older) had their weight recorded and they received significantly lower gentamicin doses than the recommended dose based on their age and weight. 11 patients received multiple doses of gentamicin with an average of 2.6 (range 2 to 4) days of therapy. The most common dose was gentamicin 240 mg. Conclusion: There was significant under-dosing of gentamicin in patients of all ages who had their weight recorded. Future studies are needed to investigate the impact of gentamicin underdosing on clinical outcomes.