Neonates intramuscular drug absorption

Drug ahsorption from an intramuscular site also may he altered in premature infants. Differences in relative muscle mass, poor perfusion to various muscles, peripheral vasomotor instability, and insufficient muscular contractions in premature infants compared with older children and adults can influence drug absorption from the intramuscular site. The net effect of these factors on drug absorption is impossible to predict phenobarbital has been reported to be absorbed rapidly, whereas diazepam absorption may be delayed." Thus intramuscular dosing is used rarely in neonates except in emergencies or when an intravenous site is inaccessible. 

Parenteral administration Absorption of medication following an intramuscular (IM) injection is often erratic in neonates owing to their small muscle mass and an inadequate perfusion of the IM site (81,82). In a study of infants and children aged 28 days to 6 years, the IM administration of chloramphenicol succinate produced serum levels that were not significantly different from those produced in intravenous (TV) administration (83). However, the bioavailability of most drugs administered intramuscularly has not been evaluated in the pediatric population. In addition to bioavailability issues, there are other concerns specific to pediatrics with the IM administration of drugs. The volume of solution injected is directly related to the degree of pain and discomfort associated with an IM injection. Manufacturers recommendations for reconstitution of IM products often... 

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