Infants oral drug absorption

Variable rates of colonisation of gastrointestinal microflora and beta-glucuronidase activity may also add to the variation and unpredictability of oral drug absorption in neonates and young infants. 

In the infant, absorption from the gastrointestinal tract of an orally administered drug differs from that in adults. Certain toxicants are absorbed to a greater extent by the young than by the adult. For example, young children absorb four or five times more lead than adults and 20 times more cadmium. In both adults and infants, the rate and extent of drug absorption depend on the degree of ionization, which, in turn, is influenced by pH. Within the first... 

Transdermal drug delivery can be used in pediatric patients (1) to avoid problems of drug absorption from the oral route and complications from the intravenous route and (2) to maximize duration of effect and minimize adverse effects of drugs. Unfortunately, the commercially available transdermal dosage forms (e.g., clonidine and scopolamine) are not intended for pediatric patients these would deliver doses much higher than those needed for infants and children. 

In addition to oral administration for hepatitis C infection in combination with interferon alfa, aerosolized ribavirin is administered by nebulizer (20 mg/mL for 12-18 hours per day) to children and infants with severe respiratory syncytial virus (RSV) bronchiolitis or pneumonia to reduce the severity and duration of illness. Aerosolized ribavirin has also been used to treat influenza A and infections but has not gained widespread use. Systemic absorption is low (< 1%). Aerosolized ribavirin is generally well tolerated but may cause conjunctival or bronchial irritation. Health care workers should be protected against extended inhalation exposure. The aerosolized drug may precipitate on contact lenses. 

The advantages of transdermal delivery can be summarised as follows. Oral absorption in the neonate is unpredictable leading to variable drug levels in the plasma and drug input cannot be readily terminated after oral dosage. Intravenous therapy is complicated by the large dead volume of the access line compared to the small drug and plasma volume in preterm infants. 

Percutaneous absorption may be increased substantially in newborns because of an underdeveloped epidermal barrier (stratum comeum) and increased skin hydration. The increased permeability can produce toxic effects after the topical use of hexachlorophene soaps and powders, salicyhc acid ointment, and rubbing alcohol. Interestingly, a study has shown that a therapeutic serum concentration of theophylline can be achieved to control apnea in premature infants of less than 30 weeks gestation after a topical apphcation of gel containing a standard dose of theophylline. " The use of this route of administration may minimize the unpredictability of oral and intramuscular absorption and complications of intravenous drug administration for certain drugs. 

Suppository is solid-like preparation made from drug and suitable bases for cavity administration. When inserted into cavities, they melt or soften, after which drug dissolution and absorption result in local or systemic effect. Whin rectal suppository is a common form which is usually used as laxatives. Administrated by rectum mucosa, suppositories possess many advantages compared with oral route. Firstly, it is a convenient administration way for infants or patients suffering from vomiting or gastrointestinal disturbances. 

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