Pharmacology Flashcards
(22 cards)
What factors affect response to medicines in children?
Age
Size
Nutrition
Growth
What are the main reasons that drug responses differ in children compared with other children or adults?
Altered pharmacokinetics
Altered pharmacodynamics
What must a drug have before marketing?
Licensing
What are the unlicensed/off-label prescribing methods used in children?
- Formulation administered via a route not intended
- Medicines used for an indication not intended
- Medicines used at a different dose to that recommended
- Children below stated recommended age limit
- Medicines without a licence, including those being used in clinical trials
What factors are different in the effect of drugs on children compared to adults?
- Neonates/infants are more sensitive to drugs than adults
- Neonates/infants are at increased risk for adverse drug reactions
- Young patients show greater individual variation
What age is categorised as adolescence in pharmacology?
12-16/18
What factors affect pharmacological differences in early post natal children?
- Rapid growth
- Highly variable alterations in drug metabolism and elimination.
- Lower tolerance to ADRs,
- Higher incidence of therapeutic errors
- Difficulty in identifying efficacy and toxicity
What factors affect pharmacological differences in infancy?
- Body weight gain + body water composition changes
- Ratio of bodyweight or surface area to organ size and function
What factors affect pharmacological differences in toddlers?
- Minor illnesses, leading to multiple short courses of therapy.
- Problems with compliance
What factors affect pharmacological differences in young children?
- Enhanced metabolism and excretion
- Clearance can change significantly during a single dose regimen
What factors affect pharmacological differences in adolescence?
- Sexual development produces major changes in in body size and composition - affects drug metabolism.
- Psychological changes and peer pressure result in smoking, alcohol and elicit drug use which can alter drug metabolism
What differences can be seen in drug absorption in children?
Oral - Reduced gastric acid/delayed gastric emptying Percutaneous -Is enhances in infants and children Intravenous -Delayed/uncertain delivery
What differences can affect distribution in children?
- High extracellular fluid
- Total body water high
- Fat content is low
What needs to be given for initial drug dosage to achieve correct plasma concentration?
Larger initial doses on a mg/kg body weight
Following initial dosage, what may need to be adjusted to compensate for decreased hepatic function/renal elimination in children?
- Dosage intervals increased
- Daily dose decreased
What differences in plasma protein binding exist in children?
- Reduced plasma protein binding in neonates
- Greater unbound or active drug
What differences in blood brain barrier exist in children?
- Not fully developed at birth
- Drugs have relatively easy access to the CNS
- Infants especially sensitive to drugs that affect CNS function = CNS toxicity
What differences can affect elimination in children?
- Neonate liver metabolism is immature, thus drugs eliminated by the liver have a longer half life
- Results in a longer time to reach steady state (4xt1/2), an increase in steady state concentration
- Applies to drugs eliminated by the kidneys
What does decreased albumin proteins in neonates cause in pharmacokinetics?
^Free drug
What does decreased hepatic metabolism in neonates cause in pharmacokinetics?
^Response to drugs
What does decreased renal elimination in neonates cause in pharmacokinetics?
^Response to drugs
What metabolic disturbances increase sensitivity to drugs in children?
- Fever
- Dehydration (increases the effects of many drugs)
- Acidosis (decreased cellular penetration of basic drugs)
