INDIVIDUALIZED DOSAGE OF GENTAMICIN - A PROGRAMMED POCKET CALCULATOR IS USEFUL ONLY WHEN APPLIED PROPERLY

Various methods of gentamicin dosing were compared in order to evaluat e factors that prevent achievement of therapeutic peak and trough plas ma concentrations in every patient. When standard doses of 3 x 80 mg o f gentamicin/day (i.e., 3 x 170-mu-mol/day) were administered, only 26 % of peak and 51% of trough plasma concentrations were within the desi red range. This percentage increased for peak levels to 54% (p < 0.001 ) when physicians were instructed in the use of a programmed pocket ca lculator (PPC) and to 70% (p < 0.001) when in addition the nursing sta ff was trained. The best results were achieved when dosing and blood s ampling were supervised by a single trained person, 76% of initial pea k and 71% of initial trough levels being within the therapeutic range. In this group of patients, further dosage adjustments by the PPC achi eved 92% of peak levels in the desired range, while no patient had ele vated trough levels. Analysis of the factors that led to these results revealed that neither the laboratory nor the PPC are limiting factors for optimal results. The goal of therapeutic plasma concentrations ca n be achieved, but requires appropriate attention to the accuracy of b lood sampling and dosing. For this purpose, a special program, i.e., m ore than ordinary attention to drug therapy, is needed.