| المستخلص: |
Gentamicin, an aminoglycoside, is a widely used antibiotic which has a narrow therapeutic range that requires TDM to optimize dosing and minimize the risk of toxicity including ototoxicity and nephrotoxicity. Aim: This audit aimed to evaluate the appropriateness of gentamicin dosing and therapeutic drug monitoring (TDM) for gentamicin at RGH, Daw Park, and to evaluate the clinical response to TDM results. Methods This was a retrospective audit of all inpatients in medical and surgical units receiving at least two or more intravenous gentamicin doses during the study period. Patients were identified by reviewing medication charts on alternate days and once a patient had been charted for a second dose. Details of demographic data and co-morbidities were also collected. The remaining data was collected after the patient's discharge to avoid any interference with the patient’s management. Relevant information which was collected included: • Patient’s demographic data, estimated glomerular filtration rate (GFR) just prior to gentamicin doses, all serum creatinine and urea readings during antibiotic treatment; co-morbidities. • Information about any previous gentamicin therapy at another hospital immediately prior to admission. • Any other antibiotic treatment during gentamicin therapy and type of infection, culture and sensitivity test results; • Gentamicin dose, frequency, side effects and other nephrotoxic drugs used • TDM results, including: concentrations, time of sampling and time of dose and the physician’s clinical action. • Infection severity indicators including temperature, WBC count, C-reactive protein (CRP). TDM considered appropriately performed if the patients: • Had three or more doses of gentamicin • Had renal impairment or renal transplant patients. • Experienced rapid decline in renal function during treatment. • On maximum dose of gentamicin, more than 7mg/kg/day, or received other nephrotoxic drugs such as vancomycin, NSAIDS, frusemide, ACEI in combination with gentamicin. • Neutropenic or immunocompromised. • Elderly (>60 years). TDM was inappropriate if: • TDM was not performed as indicated in the above type of patients. • No time recorded. • No TDM performed. Results: Of 75 TDMs (30 patients), 47 (62.6%) were performed appropriately and 28 (37.3%) were inappropriately done, for various reasons. The reasons behind inappropriate TDM performance included inappropriate timing (which was the most common reason at 67.8%), large intervals between gentamicin TDMs (17.8%) or non-performance of TDM (14.2%). The urology unit contributed to the largest number of inappropriate TDMs (35.7%), while respiratory, cardiology and general medicine units had equal distributions of inappropriate TDM (14.2%). Adherence to GFR+ module recommendations for gentamicin dosing occurred in 50% (n=15) of patients. Conclusion: Gentamicin TDM and dosing at RGH were inappropriate in many cases due to modifiable reasons such as timing and following the GFR+ module recommendations to determine the initial and maintenance dose of gentamicin. This can be improved by education of physicians, nurses and clinical pharmacists to increase awareness of appropriate use of TDM and GFR+ decision support during gentamicin therapy.
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