RELATIONS BETWEEN AGE AND WEIGHT AND DOSAGE OF DRUGS

Abstract

BECAUSE of the existence of individual variability in response to drugs, no method can be devised for determining accurately in advance the proper dosages of drugs for individuals. Average doses, suitable for large groups of adult patients, have been worked out empirically and are printed in pharma-copoeias. This paper is concerned with a survey of methods by which drug dosage might be modified for age and size of individual. It is natural to proportion dosage according to size of patient, and I suppose it was done even by our Stone Age ancestors. We have today a rule for doing this, Clark's rule, or the weight rule, to take the adult dose as that for a person weighing ISO lbs. and change the dose as necessary in direct proportion to the weight of the patient. The weight rule is repre-sented in figures 1, 2 and 3 by the diagonal straight lines. A person of weight 70 kg. (154 lbs.) is to receive 100 per cent of the adult dose; per-centages for those of lesser weights may be read off directly from figures 1, 2 and 3, and for those of greater weights from figure 3, line 1.0.