EFFECT OF HEATING SERA UNDER CONDITIONS NECESSARY FOR DEACTIVATION OF HUMAN-IMMUNODEFICIENCY-VIRUS ON COMMONLY MONITORED THERAPEUTIC DRUGS

Minimizing the risk of infection of laboratory staff from contaminated blood samples is a major safety goal in a clinical laboratory. One dangerous pathogen, the human immunodeficiency virus (HIV) can be deactivated by heating sera at 56 degrees C for 30 min. We studied the effect of such heat treatment on serum concentrations of 11 commonly monitored therapeutic drugs. We used blood specimens collected in serum separator tubes (SSTs), which were routinely submitted for therapeutic drug monitoring in our laboratory for this study. Concentrations of digoxin in sera were measured using a fluorescence polarization immunoassay (FPIA), while concentrations of tobramycin, gentamicin, vancomycin, theophylline, valproic acid, procainamide, N-acetylprocainamide (NAPA), phenytoin, phenobarbital, and carbamazepine were measured by enzyme-multiplied immunoassay technique assays using a Monarch 2000 analyzer. We observed no significant change in the concentration of any drug except phenytoin and carbamazepine following heating at 60 degrees C. The decrease in concentration of phenytoin and carbamazepine after heating was related to absorption of the drug to the gel rather than the instability of the drug under heating conditions. We conclude that blood contaminated with HIV may be deactivated by heating prior to analysis for most of the routinely monitored therapeutic drugs.