The pharmacokinetics of new oral cephalosporins in children.

Differences in the pharmacokinetic parameters of cephalosporins between children and adults may be predictable on the basis of the level of maturation of the physiologic processes involved in drug disposition. It appears that the most important of these factors (gastrointestinal, renal and hepatic function) are reasonably mature by the age of 1 year. As a result, the primary difference between adults and children relates to size and body composition. Comparable bioavailability is expected in children and adults. However, absolute values for systemic clearance (ClS) and volume of distribution (VSS) will be lower in children. It has been suggested that ClS in children is reduced in proportion to body surface area. This may also be true for the VSS of the cephalosporins since they distribute primarily into the extracellular fluid space which has been shown to be similar in children and adults when adjusted for surface area. If both ClS and VSS are proportional to surface area, half-life will be similar in adults and children. Data with cefetamet generally support these principles. Clearance normalized for body surface area averaged 69.3 ml/min/m2 in children aged 3-7 years, 64.9 ml/min/m2 in children of 8-12 years and 68.9 ml/min/m2 in adults. The VSS remained somewhat smaller in children than adults even after correction for surface area. Bioavailability and elimination half-life in children were similar to values in adults. Data with other new cephalosporins are limited, but differences between children and adults in bioavailability and half-life appear to be insignificant.(ABSTRACT TRUNCATED AT 250 WORDS)