THERAPEUTIC DRUG-MONITORING OF GENTAMICIN - A 6-YEAR FOLLOW-UP AUDIT

Background and objective: In 1984 a therapeutic drug monitoring (TDM) service was established in Hospital Universiti Sains Malaysia (HUSM) a nd gentamicin concentrations were measured and used to design optimal regimens for the antibiotic. In this study we report on a 6-year follo w-up audit since our first assessment of the service. Method: Records of 733 requests for gentamicin monitoring were reviewed. Results: Of t he 592 patients involved, 39% were neonates and 42% were adults. Peak gentamicin concentrations were within the therapeutic range in 65% of the patients at first monitoring and 79% of the corresponding trough c oncentrations were within the non-toxic range. After dosage adjustment , 81% of the peak concentrations were within the therapeutic range and trough concentrations rose to levels regarded as toxic in 7% of patie nts. In patients with therapeutic peak concentrations at the first mon itoring point, the average duration of gentamicin therapy was statisti cally shorter than in those patients who failed to achieve a therapeut ic peak concentration. The distribution of gentamicin peak and trough concentrations in terms of therapeutic ranges were also better than th ose found in 1990. Conclusion: TDM for gentamicin is well accepted in HUSM and its application has contributed to improved gentamicin admini stration. Furthermore, our physicians are now able to choose more appr opriate dosage regimens for their patients because the majority of gen tamicin concentrations attained even at the first monitoring were with in the therapeutic range.