Evaluation of target concentration intervention strategy of gentamicin therapy in a malnourished patient population of south India.

BACKGROUND & OBJECTIVE: Aminoglycoside antibiotics, especially gentamicin, are widely used in suspected Gram-negative infections in India. Therapeutic drug monitoring is not commonly used for this drug in our population. We evaluated the target concentration intervention (TCI) strategy of gentamicin therapy in a predominantly malnourished patient population with lower respiratory tract infection in south India. METHODS: Patients who were prescribed gentamicin for suspected lower respiratory tract infection were randomized to any of the three groups, viz., control (CG), once daily dosing (ODD), and pharmacokinetic dosing (TCI) groups. Diagnosis was initially done by clinical evaluation and confirmed radiologically. Patients in CG received 80 mg gentamycin twice daily, ODD group received 160 mg once daily, and TCI groups received 160 mg once daily initially followed by dose revision based on serum drug levels. Blood samples were collected at peak and trough levels and assayed for gentamicin concentration. Dose adjustment was done in TCI group whereas the other groups received standard doses. Efficacy and safety were evaluated as outcome measures. RESULTS: Of the 52 patients included initially in the study, 43 (CG 20, ODD 12, TCI 11) completed the study. The doses administered to the study subjects were less than those prescribed in standard textbooks and guidelines. Patients in TCI group had their gentamicin doses revised upwardly to a dose of 4.3+/-0.6 mg/kg to achieve a peak gentamicin concentration of 12 to 15 microg/ml. Both ODD and TCI groups showed significant improvements in outcomes studied over the control group. INTERPRETATION & CONCLUSION: The results of our study indicated that once daily dosing of gentamycin was superior to multiple daily dosing in treating the lower respiratory tract infection in the study population. All patients in the ODD and TCI groups achieved satisfactory serum drug concentrations at administered doses (160 mg/day for ODD and <or= 200 mg/day for TCI group). In our study, target concentration intervention did not significantly improve the therapy outcomes. Since the study sample is small further research may be needed.