What is the main route of drug elimination in pediatric patients?
Drug elimination in pediatric patients can occur via multiple routes, including exhalation, biliary secretion, and renal clearance. Of these, the kidney is the primary organ responsible for the excretion of drugs and their metabolites.
Is drug excretion slower in children?
Drug metabolism and elimination vary with age and depend on the substrate or drug, but most drugs, and most notably phenytoin, barbiturates, analgesics, and cardiac glycosides, have plasma half-lives 2 to 3 times longer in neonates than in adults.
How does drug metabolism differ in infants from adults?
At birth, both phase I and II metabolic enzymes may be immature. The different capacity to metabolize drugs in children may result in higher or lower drug plasma levels than those reached in adults .
Why would neonates and infants have decreased metabolism and excretion of drugs?
Metabolic processes are often immature at birth, which can lead to a reduced clearance and a prolonged half-life for those drugs for which metabolism is a significant mechanism for elimination. Renal excretion is also reduced in neonates due to immature glomerular filtration, tubular secretion, and reabsorption.
How does drug excretion differ in children?
The renal excretion of unchanged drug is generally lower in newborns owing to the immaturity of renal function. However a similar or greater rate of renal excretion has been observed in infants and preschool children compared with adult values for some drugs, including levetiracetam 62, cimetidine 63 and cetirizine 64.
Why are infants at risk for drug toxicity?
Infant kidneys have a higher resistance to blood flow, incomplete Lenle’s Loops, incomplete glomerular and tubular development, low glomerular filtration rate, and decreased ability to concentrate urine. As a result, drugs are excreted more slowly, drug accumulation can occur, leading to toxicity.
Why do infants have a higher risk for drug toxicity?
Why do infants require smaller doses of drugs?
Infants have a higher percentage of extracellular water, and stores of body fat increase throughout childhood. Changes in volume of distribution can alter the drug’s half-life, requiring adjustment of the dosing interval, as seen with digoxin.
How is elimination achieved in pediatric patients?
Elimination of drugs and their metabolites occurs predominantly via the kidneys. The glomerular filtration rate (GFR) is 2 to 4 ml min−1 1.73 m−2 in term neonates, and it doubles by 1 week of age, reaching adult values by the end of the first year of life.
How does Pediatrics affect drug dosing?
Why pediatric doses are lesser than normal doses?
There is often a lack of pharmacokinetic studies in children of different ages. This can make it difficult to know what the optimum dose is for a child. Many doses are based on the child’s age or weight. This does not always allow for the different rates of childhood development.
What is the relationship between drug excretion and toxicity in infants?
Rates of drug excretion in the infant are lower than the excretion rates in children and adults. incomplete glomerular and tubular development, low glomerular filtration rate, and decreased ability to concentrate urine. As a result, drugs are excreted more slowly, drug accumulation can occur, leading to toxicity.
Why are drug-metabolizing enzymes immature in infants?
Drug-metabolizing enzymes in the liver of infants are immature. Drugs are not biotransformed in inactive compounds as readily as they are in children and adults, resulting in higher levels of circulating active drugs and greater potential of toxicity.
Why are drugs excreted from the body through breast milk?
The particular importance of the excretion via breast milk lies in the toxic effects of some drugs on the breastfeeding infant. Note that substance-specific portions of orally administered drugs are removed with feces without entering the circulation. This is due to their incomplete absorption from the gastrointestinal tract.
What are the pharmacokinetics of infants?
Pharmacokinetics in Infants. Drug actions in infants are variable because of the infant’s physiological attributes: small body mass, high relative body water content, low body fat, greater membrane permeability of the skin, and blood-brain barrier and reduced plasma-binding abilities.