CPTP 2.3 Flashcards
Explain how liver disease can affect drug metabolism
- The healthy liver facilitates rapid and extensive uptake and metabolism of lipid soluble drugs
- First pass metabolism is considerably reduced in individuals with chronic liver disease and so the bioavailability may be much greater than in a healthy individual
- The dose of a drug may need to be reduced for individuals with hepatic disease
Explain how cardiac disease can affect drug metabolism
- The rate of metabolism of many drugs is dependent on drug delivery to the liver via the bloodstream
cardiac failure –> reduced blood flow –> reduced clearance
The dose of a drug may need to be decreased for individuals with cardiac failure
How can thyroid disease affect drug metabolism
Drug metabolism is increased in hyperthyroidism
Drug metabolism is decreased in hypothyroidism
GFR is reduced in newborns, elderly, kidney and heart disease. Explain how reduced GRF can affect drug metabolism
- Less drug filtered
- Longer lasting drug action in body
- Need to decrease drug dose and increase dose interval
The level of bilirubin increases in neonates. Explain this.
- Neonates have low activity of cytochrome P450 and UDPGT
- Low UDPGT means lack of conjugating activity
- Therefore less bilirubin undergoes conjugation by UDPGT before excretion.
Explain how aging can affect drug distribution
- Decrease in body water and increase in body fat with age
- So there would be decreased Vd of hydrophilic drugs and increased Vd of hydrophobic drugs
Explain how aging can affect drug metabolism
- hepatic blood flow and liver mass decrease with age
- So hepatic metabolism may be reduced
Explain how aging can affect renal excretion
- GFR and tubular excretion decrease with age
- So renal elimination is reduced
- Elderly are frequently taking multiple medications –> increased risk of drug-drug interactions
