Clinical pharmacology of renal disease Flashcards
Define therapeutic index
Comparison between the dose that will bring the desired effect and the dose that will cause toxicity
It is a ratio of the largest, non-toxic does: minimum dose to bring an effect
Why is knowing the clearance of an individual important
If the clearance is poor and there is a high systemic exposure of the drug, it can cause toxic effects
What 3 functions make up clearance in the kidney
Filtration
Secretion
Reabsorption
What must drugs be to be filtered
Free in the plasma
What does no secretion and reabsorption mean for clearance
There is total clearance
What clearance is measured to measure the GFR
creatinine and inulin
Where do secretions mainly occur
Proximal tubule
How are drugs which are too large to be filtered, cleared
they are secrted into the proximal tubule
What is the effect of secretion on clearance
Causes increased clearance because the plasma concentration of the substance decreases while the amount present in the urine increases
How are weak acids cleared from the body
Sodium bicarbonate is used to make the urine more alkaline which causes the weak acids to diffuse into the urine to neutralise it (this occurs in aspirin overdose)
What is the effect of a drug having a higher distribution
They have a longer elimination half life and their therapeutic effect is not as driven because it is the drug present in plasma which drives the therapeutic effect
Why is the combination of gentamicin and furosemide bad
They are nephrotoxic together
How to do therapeutic drug monitoring (TDM)
frequently measure the drug concentrations in the body and adjust them to get the desired effect
What is the benefit of a drug which isn’t excreted by the kidneys
It can be used in patients who have low GFR who have low clearance at the kidneys
How can a drug cause acute tubular necrosis
While the drug is in the tubule, it can directly affect the epithelial cells which results in AKI
