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Week 50: CKD > Pharmacology of CKD > Flashcards

Flashcards in Pharmacology of CKD Deck (9)
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Bioavailability definition

The fractional extent to which a dose of a drug reaches its site of action


CKD impact on absorption

In general, there is no major impact
Except in a patient with severe, generalized, pitting edema who may have gut edema that reduces/slows oral absorption


Factors influencing distribution

Lipid solubility
Molecular weight
pH gradients
Protein binding (most important)


How does phenytoin need to change in CKD?

Phenytoin has 0 order kinetics
Hypoalbuminuria results in a higher risk of toxicities
Adequate seizure control can be obtained at concentrations below the normal reference range


How does digoxin need to change in CKD?

Digoxin is significantly eliminated by the kidneys and uremia results in decreased tissue binding
The result is that the concentration increases in systemic circulation - so need to decrease the dose


Volume of distribution definition

The theoretical volume of fluid into which the total drug administered would have to be diluted to produce the concentration in the blood


Are drugs with a
1. Small Vd (<1 L/kg)
2. Large Vd (>2 L/kg)
more or less likely to be eliminated by dialysis

1. More likely (water soluble and remain in circulatory system)
2. Less likely (lipid soluble and distribute into extravascular tissue)


What are the rules for drug dosing based on renal or non renal drug clearance?

If non-renal clearance is large (>70%), then you use normal drug dosing
If renal clearance is significant (>30%), then the drugs half like will be prolonged with reduced GFR and you need to adjust the dose


Size of drugs that can filter through the glomerulus

< 60,000 Da
Cannot go through if bound to proteins