Introduction: Therapeutic drog monitoring (TDM) was established to determine serum or blond levels of drugs, which are potentially toyic. Aminoglycoside antibiotics, vancomycin, theophylline, digoxin and antiepileptic agents are among the most frequently monitored drugs due to their narrow therapeutic index and individual dose-response relationship. The purpose of this preliminary retrospective study was to assess the extent to which therapeutic drog monitoring influences subsequent patient treatment with a given drog. The study took place at the multi-organ transplantation institute of clinical and experimental medicine with a department of clinical pharmacology. The study was designed as retrospective TDM data assessment, re-evaluation of serum levels, interpretation, recommendation and outcomes for a one-year period. Materials and methods: Data from 437 very heterogeneous patients. samples analysed for a one-year period was reviewed for monitored drugs namely, gentamicin, amikacin, netihnicin, vancomycin, and digoxin, using the fluorescence polarization immunoassay (FPIA) method with Abbott TDx analyser for determination of serum drog levels, and MW/Pharm version 3.0 for pharmacokinetic analysis. Results: Intervention based on TDM results was necessary in 50 % GEN, 3S % AMI, 52 % VAN, and 4 out of 7 NET treated patients, respectively. Surprisingly, 5S % of patients undergoing long-term DIG ingestion proved to have serum levels below published therapeutic ranngs, whereas in 13 % drog withdrawal was warranted due to toxic levels measured and renal function deterioration, as predicted by increased serum creatinine and other markers associated with possible toxicity, despite the absence of clinical manifestation of real toxicity. Conclusion: These data confirm tkat therapeutic drog monitoring plays an undeniable role in providing Bafe and qualifled pharmacotherapy if indicated and interpreted skillfully.

        Key words: drog serum level, nephrotoxicity, cardiotoxicity, therapeutic range.