The Potential Role of Therapeutic Drug Monitoring in the Treatment ...

International AIDS Society–USA Topics in HIV MedicineIn the treatment of drug-experienced subjects who havedrug-resistant virus, determining a protein-corrected IC 50 maybe useful. Applying TDM to then achieve a concentration several-foldabove that IC 50 would seem reasonable. Evaluation of theinhibitory quotient (IQ), in which the phenotypic sensitivity ofthe virus to the drug and the plasma concentration of the drugdetermine the IQ, is being studied in clinical trials. Welldesignedand adequately powered prospective studies need tobe performed before IQ can be generally recommended for clinicalpractice.The important message about TDM is that it may ultimatelyprove useful, but at this time there are not enough data to recommendits use outside of very specific circumstances. TDMshould currently be viewed as an investigational tool to exploremeans of improving therapeutic outcome and reducing toxicitiesin the treatment of HIV infection.Financial Disclosure: Dr Gerber has served as a consultant to Agouron, Merck, RocheDiagnostics, and Roche Pharma. Dr Acosta has served as a consultant to Bristol-MyersSquibb, Merck, and Roche.References1. Schumacher GE, Barr JT. Economic and outcome issues for therapeuticdrug monitoring in medicine. Ther Drug Monit. 1998;20:539-542.2. Spector R, Park GD, Johnson GF, Vesell ES. Therapeutic drug monitoring.Clin Pharmacol Ther. 1988;43:345-353.3. Morse GD, Shelton MJ, O'Donnell AM. Comparative pharmacokinetics ofantiviral nucleoside analogues. Clin Pharmacokinet. 1993;24:101-123.4. Acosta EP, Henry K, Baken L, Page LM, Fletcher CV. Indinavir concentrationsand antiviral effect. Pharmacotherapy. 1999;19:708-712.5. Baede-van Dijk PA, Hugen PW, Verweij-van Wissen CP, Koopmans PP,Burger DM, Hekster YA. 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