Drugs in paediatric population Flashcards
Paediatric age group
Neonates- 0-28 days
Infant- 1-12 mths
Child - 1-12 years
Adolescent- 13-18 yrs
Absorption changes in age groups
Gastric PH:
Neonates- pH 6-8 (enhanced absorption of acid-labile medicines, e.g. penicillin). Can increase/decrease absorption of weak acidic or basic drugs.
By age 2- gastric pH reaches adult level
Gastric emptying time:
Neonates and infants have long time. Impaired drug absorption= risk of ADR
Peristalsis:
Neonates have irregular peristalsis, results in enhanced absorption.
IM: delayed in infants and neonates. Rarely used. Enhanced skin permeability.
Rectal: neonates= incomplete and slow absorption.
Distribution changes in age groups
Body composition:
Vd changes.
Total body water (TBW) higher in fetus, neonates, infants, and children.
Children have lower body fat.
Hydrophilic drugs need higher doses.
Lipid soluble drugs need lower doses.
Protein binding:
Decreased in neonates.
Highly protein bound drugs are less protein-bound in neonates than older children.
Increased free or unbound drug in serum cause harm.
E.g. kernicterus (bilirubin moves from blood stream into brain tissue) and jaundice (excess bilirubin in blood).
Metabolism changes in age groups
Full hepatic metabolic capacity occurs at 6 mths.
Paracetamol, diazepam, theophylline, and phenytoin have long elimination half lives in neonates.
Morphine given in higher doses in premature infants.
Saturation kinetic drugs (theophylline) monitored closely
Excretion changes in age groups
It takes weeks to a year to develop renal function.
Clearance of renally excreted drugs is prolonged in infants.
Aminoglycosides, digoxin, penicillin, and cephalosporins are slowly eliminated in neonates vs older children and adults.
E.g. gray baby syndrome (IV chloramphenicol as it accumulates from low liver enzymes)
Importance of factors affecting drug therapy (liver/renal impairment, obesity)
Hepatic disease- drug clearance decreased, e.g. morphine, lidocaine, propanolol.
Renal- decreases dosage requirement of drugs eliminated by kidney (aminoglycosides and vancomycin)
Obesity- Metabolic complications (T2DM, high BP, high cholesterol)
Evaluate common diseases and principles of drug dosing
Cold, N/V, asthma, epilepsy, dermatology, diabetes, mental health.
Safe= not overdoses
Effective= sufficient to relieve symptoms
Measurable= measure using tools
Measure dose by weight in kg x mg per kg recommended
Exceptions: chemo (BSA), above or below IBW
Increments
Used when rounding dose
2.435ml dose and increment 0.1 = 2.4ml
2.435ml dose and increment 0.5ml= 2 or 2.5ml
Rounding
Up- wide therapeutic index or max daily dose higher than dose needed. Antibiotics.
Down- Narrow therapeutic index (paracetamol, pseudoephedrine and antihistamines)
Be familiar with resources for provision of drug information in paediatrics
AMH, APF, AUSDI, MIMS, eTG
