[Pharmacokinetics and dosage regimen in children (author's transl)].

Dosage recommandations are mostly established empirically. With many drugs more accurate dosage is necessary and possible: antibiotics, cytostatic drugs, but also heart glycosides and anticonvulsives. Some pharmacokinetic standard values vary according to age. The distribution volume in infants is normally substantially greater than in older children. For infants the first or single dose has to be higher in relation to body weight to get the same concentration as for older children. In general, the elimination rate is slower in younger children. Therefore in long-time therapy the interval between doses has to be longer. After the 6th to 12th week the differences in elimination rates are negligible. The absorption from the rectum is neither reliable nor predictable. Suppositories are only allowed if it is possible to calculate the effect of a drug on the patient. Enteral absorption in infants is slower than in older children. Therefore maximum concentration will be reached later and will be not as high as in older children. The local concentration correlates well with plasma concentration. Drugs in bib or feeder have no effect.