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Standards of aminoglycoside therapeutic drug monitoring in a South African private hospital: perspectives and implications

Mariette du Toit
Johanita R Burger
Dorcas M Rakumakoe
Malie Rheeders


Background: Therapeutic drug monitoring (TDM) is essential to ensure that aminoglycoside peak concentrations are high enough for effective antimicrobial treatment and trough levels are low enough to minimise toxicity. Inappropriate utilisation of TDM may lead to suboptimal therapy, toxicity and waste of resources. This study aimed to investigate the standard of aminoglycoside TDM performed in adult hospitalised patients.

Design: An observational, descriptive, cross-sectional study.
Setting: A 221-bed private hospital.

Participants: All patients, older than 18 years, on intravenous aminoglycosides for more than 48 hours were included.

Interventions: None, was observational. A computerised database and patient files were used to obtain the information required for this study. Descriptive statistical analysis was used.

Main outcomes measures: Aminoglycoside blood levels and estimated glomerular filtration rate (eGFR) in the patients.

Results: One hundred and three (103) patients were included: 65 on gentamicin and 38 on amikacin. Blood levels were performed in only 19 gentamicin (29.23%) and 22 amikacin (57.89%) patients. Trough levels were taken more than 2 hours before the next dose in 12 gentamicin (63.16%) and 12 amikacin (54.54%) patients. The majority of patients (96.92% on gentamicin and 84.21% on amikacin) received once daily doses. TDM was performed in all patients with an estimated glomerular filtration rate (eGFR) lower than 60 mL/min/1.73m2 and in 23.31% of gentamicin patients and 56.76% of amikacin patients with an eGFR higher than 60 mg/min/1.73m2.

Conclusions: Incorrect sampling times and unnecessary levels taken in patients with normal renal function indicate a need for aminoglycoside treatment guidelines in the private hospital.

Funding: None

Keywords: Aminoglycosides, Dosing considerations, South Africa, Therapeutic DrugMonitoring, Sampling times