title: Drug disposition during the perinatal period.
abstract: During the perinatal period the problems of drug disposition are pronounced. The adaptation from the maternal-fetal unit to extrauterine life leads to alterations in drug absorption, distribution, metabolism, and renal elimination. Since both morphology and function of the alimentary tract changes, drugs are absorbed more slowly in the neonate than in older infants. Moreover, the serum protein binding of drugs is reduced in neonates. Consequently a measured plasma concentration may reflect a higher plasma/tissue level in the newborn as compared with adults. If the distribution volume of a drug corresponds to the total body water or extracellular water space, the dosage may be calculated in relation to the individual variations in the body surface area. But this procedure is not applicable for the newborn infant due to impaired metabolic functions of the liver and renal elimination mechanisms. The capacity of drug oxidation and glucuronidation is not fully developed in the neonate. Also glomerular filtration and tubular secretion are reduced during the first weeks of life. Therefore the elimination half-lives of many drugs are considerably prolonged in the newborn compared with that in older infants. As a consequence, individual therapeutic drug monitoring based on pharmacokinetic concepts and assisted by computer programs is becoming increasingly important.
mesh_terms: D001798:Blood Proteins / Q000378:metabolism; D001825:Body Fluid Compartments; D005919:Glomerular Filtration Rate; D006801:Humans; D007231:Infant, Newborn; D007273:Injections, Intramuscular; D007408:Intestinal Absorption; D007668:Kidney / Q000378:metabolism; D007700:Kinetics; D004364:Pharmaceutical Preparations / Q000378:metabolism*; D011485:Protein Binding; D012869:Skin Absorption
chemical_list: D001798:Blood Proteins; D004364:Pharmaceutical Preparations