The repeated one-point method for predicting dose sizes with irregular dosing intervals.

To initiate drug therapy a preliminary dosage regimen is often calculated using literature values for pharmacokinetic parameters. However, in some cases literature data are not available or indicate large interindividual variations, or in certain cases an altered volume of distribution (such as in acute congestive heart failure, edema, obesity, etc.) and changes in renal and nonrenal elimination are expected. For such cases the repeated one-point method (ROPM) was suggested. The ROPM like the other methods for dosage regimens assumes equal maintenance doses at equal dosing intervals. Yet, in practice and in most hospitals, doses administered 3 or 4 times daily are often not administered at equal intervals. A modification of the ROPM is suggested for unequal dosing intervals. The following 4 situations are presented: different dose sizes to maintain Cssmin constant, different dose sizes to maintain Cssmax constant, equal dose sizes where the highest peak does not exceed a certain maximum concentration and equal dose sizes where the lowest trough does not fall below a certain minimum concentration.