Vancomycin Dosing and Pharmacists’ Contribution to Therapeutic Monitoring: Single Centre Retrospective Study - Abstract
Background: Vancomycin is an antibiotic with a narrow therapeutic index. Due to this and the need to obtain early effective levels without inducing adverse effects is a clinical challenge. Vancomycin dosing and monitoring guidelines are available from professional societies and hospitals, but the adherence to these has a wide rate of success, including with pharmacists’ input. Objectives: To investigate adherence to vancomycin guidelines, therapeutic drug monitoring (TDM), therapeutic range (TR) attainment and the impact of clinical pharmacists on these parameters. Method: Single centre, retrospective audit reviewed adults who received vancomycin between 2014-2015. Data was extracted from digital medical records and TDM sheets completed by pharmacists. Adherence to hospital guidelines was analysed for dosing, adjustments for renal function and body weight. Results: 525 vancomycin courses were reviewed with a mean duration of vancomycin use of 5.1 days with a mean of 2.7 trough levels taken. Pharmacists’ involvement in vancomycin therapy resulted in a mean of 1.13 trough levels in TR per patient versus 0.51 (p<0.001) without pharmacist involvement, as well as a mean of 1.61 appropriately taken levels versus 1.00 (p<0.001). 328 patients had a recorded weight; 160 received a loading dose, 46.9% were under-dosed and 5% were overdosed. Initial maintenance doses were under-dosed in 22.2% patients and overdosed in 13.4% patients. Initial frequency was lower than recommended in 7.6% patients and higher in 21.6% patients. Conclusion: This study identified that there was low adherence to the hospital’s guidelines for vancomycin dosing and monitoring. Pharmacist involvement improved monitoring and TR attainment.