EXCRETION Flashcards
Excretion definition
Excretion is the passage out of systemically absorbed drugs
Sites of secretion
Urine, GIT, Exhaled air, Sweat, Milk, Saliva
Renal excretion happens in 3 phases
1) Glomerular filtration
2) Tubular reabsorption
3) Tubular secretion
What is filtered during glomerular filtration
All non-protein bound drug whether lipid-soluble or lipid-insoluble is filtered
Glomerular filtration of a drug depends on ……………….. and …………
its plasma protein binding ……… renal blood flow.
Tubular reabsorption occurs by ……
passive diffusion
Tubular reabsorption depends on
Lipid solubility and ionization of the drug at the existing urinary pH
What drugs are reabsorbed by the tubules
Lipid-soluble drugs only
What type of drug is less absorbed in acidic urine?
Weak bases because they are more ionized
What type of drug is less absorbed in alkaline urine?
Weak acids because they are more ionized
How to eliminate a drug in poisined person?
Urine in alkanized in barbiturate and salicylate and asprin poisoning
Tubular secretion definition
It is the active transfer of organic acids and bases by 2 seperate classes of relatively non-specific transporters present at the proximal tubules
The gates at the proximal tubules are highly specific so they are site of ……..
Drug competition and drug interactions
Weak acid drug examples
Penicillin, uric acid, probenecid
Weak base drugs examples:
Digoxin , quinidine
How to decrease urinary excretion of penicillin?
Add probenecid
How to decrease urinary excretion of digoxin?
Add Quinidine
Quinidine is used to treat ….
Heart arrhythmias
What is excreted through saliva?
Iodine, morphine and heavy metals
What is excreted through stomach?
Morphine
What is excreted through large intestine?
Unabsorbed oral drugs or bile excreted drugs
What is excreted through bile?
Some can be absorbed and enter the enterohepatic circulation like morphine and digitoxin
Some antibiotics are excreted in bile like ampicillin and rifampicin used to treat typhoid fever
What is excreted through exhaled air?
Gases and volatile liquids (general anesthetics and alcohol)
What is excreted through sweat?
Heavy metals and rafimpicin
What is excreted through milk?
MOst drugs enter breast milk by passive diffusion
Example: Morphine, purgatives and tetracycline
