Pharmacology Flashcards
What in unlicensed/off-label prescribing?
Formulation administered via route not intended
Used for indication not intended
Used at different dose to that recommended
Below stated recommended age limit
Medicines without a license
Why are neonates/infants more sensitive to drugs than adults?
Organ system immaturity
Why is prescribing in young children difficult?
Enhanced metabolism and excretion
Clearance can change significantly in a single dose regimen
What SSRI when used in children for treatment of depression is associated with 4x increase in suicide compared with placebo?
Paroxetine
What must you think about re: drug absorption and bioavailability in children if wanting to administer by oral route?
Reduced gastric acid Delayed gastric emptying Absorption not reached adult values until 6-8mo High hepatic clearance First pass elimination reduced
What must you think about re: drug absorption and bioavailability in children if wanting to administer by percutaneous route?
Percutaneous route is enhanced in infants/children
Think when damaged skin or steroids!
What must you think about re: drug absorption and bioavailability in children if wanting to administer by rectal route?
Used when vomiting/unwilling
Avoids first-pass metabolism
What must you think about re: drug absorption and bioavailability in children if wanting to administer by IV route?
Delayed/uncertain delivery
Why is the body composition important when thinking about drug distribution?
Newborns = high extracellular fluid volume
Total body water high
Fat content low
In terms of drug dosage, why is high extracellular fluid volume important?
Larger initial doses on a mg/kg body weight to achieve correct plasma conc.
After loading dose, dosage interval increased or daily dose decreased to compensate for decreased hepatic function/decreased renal elimination
What happens to plasma protein binding in neonate?
Reduced
What does reduced plasma protein binding in a neonate mean for drugs?
Greater unbound or active drug
Why is the blood-brain barrier important in neonates?
Not fully developed at birth
Drugs have easy access to CNS
Why are infants especially sensitive to drugs that affect CNS function?
Not fully developed BBB = CNS toxicity
Why is it important to know that a neonates liver metabolism is immature?
Drugs eliminated by liver have longer half life
How is hepatic metabolism in the neonatal period?
Very slow
Why is hepatic metabolism very slow in neonatal period?
Immaturity of drug metabolising enzymes
What time of drugs are neonates especially sensitive to?
Drugs eliminated by hepatic metabolism
When is the metabolic activity the same as adult activity?
By 1yr of age
When is metabolic metabolism more rapid and the half life shorter?
1-8yr children
Why is it important to know metabolic metabolism is more rapid and the half life shorter in 1-8yrs?
Some drugs (anti-epileptics) need to be greater dose than in adults
What is renal excretion like in neonates?
Decreased
When are adult values for renal excretion achieved?
3-6mo
When is tubular function in kidneys same as adults?
12mo
What does decreased albumin protein levels mean for drugs?
Increased free drug levels
What does increased free drugs levels mean?
Increased reponse
What does a decreased hepatic metabolism mean for drugs?
Increased response
What does a decreased renal elimination mean for drugs?
Increased response
What does a decreased BBB mean for drugs?
Increased CNS effects
What metabolic disturbances mean that sensitivity to drugs is increased?
Fever
Dehydration
Acidosis
