Pharmacology in Chronic Disease Flashcards
List some of the Pharmacokinetic changes that can occur in the elderly:
Volume of distribution reduces:
- Reduced Body water
- Increased Fat
First pass metabolism:
- reduced
- P450 Enzymes drastically reduced
Reduced Renal function
- 30% have severe changes
List some of the difficulties/ complications in prescribing medication to the elderly:
Reduced Volume of distribution
Reduced First pass metabolism
Reduced Clearance
- Reduced Renal function
Increased Susceptibility to drugs
Increased risk of - adverse drug reactions
Drug - disease interaction
Drug interactions
Prescribing cascades
Name some drug disease interactions commonly seen in the elderly:
NSAIDs exacerbating chronic heart failure
Urinary retention in BPH on decongestants
Constipation with calcium channel blockers
Name important drug to drug interactions to be avoided:
Statins : Macrolides
Ca2+ blockers : Beta blockers
Warfarin : NSAIDs
ACE Inhibs : Sulfonylureas
Define prescribing cascades and give three examples;
Giving drugs to cure the side effects of other drugs.
NSAIDS > HTN > Anti HTN therapy
Metoclopramide > Parkinsonism > Anti- parkinsonism drugs
Diuretic > Gout > NSAIDs > Anti- HTN therapy
Name some drugs that have a much greater effect on the elderly:
Alcohol
Opiates
Sedatives
Outline the pharmacokinetic changes in renal disease:
Decreased elimination
Decreased protein binding
Decreased Hepatic metabolism
Outline the pharmacodynamic changes that occur in renal disease:
Altered Sensitivity to drugs
Name some keys drugs to be aware of in reduced elimination rates in kidney disease:
Aminoglycosides
Lithium
Digoxin
Methotrexate
Penicillins
How is reduced renal clearance management when it comes to prescribing?
*accurate determination of renal function
alteration of the dosage schedule
- increased spacing
Monitoring drug concentrations
List the drugs that should be avoided, or reduced in dose in renal disease:
Antibiotics = reduced dose
LMWH = reduced dose
Digoxin = reduced dose
Phenytoin = Reduced dose
ACE Inhibitors = Cation
NSAIDs = avoid
Metformin = Avoid
In summary of renal disease what is the main points to think about when prescribing?
There will be prolonged elimination time, therefore drugs may build up to dangerous levels.
therefore:
- Increase dosing interval
What Pharmacokinetics are effected in hepatic disease?
First pass metabolism
Activation of prodrugs
Extraction rate
What drugs are most effected by impaired first pass metabolism, leading much higher levels in the blood?
Verapamil - 140%
Paracetamol - 50%
Chlormethiazole - 1000%
What is the main thing that must be done when prescribing in liver disease?
Lower dose
Increased Dosing interval
