Small general purpose analog computers are not usually equipped for iterative computation. Since multiple dosage problems are often encountered in pharmacokinetic studies an approximating program is proposed for rapid estimation and curve fitting. The program produces an input function simulating a staircase by integration only of the positive differentials of a sequence of rectangular impulses. The program is used to compute the maximum and minimum concentration factors of Sparteine and Quinidine as examples of two substances obeying first order kinetics. It is apparent from the results that the choice of dosage schedules is restricted both by the pharmacological and the pharmacokinetic properties of the drugs.