Metabolism and Excretion Flashcards
List 7 inducers
Rifampin St. John's Wort Phenobarbitol Phenytoin Carbamazepine Tobacco Smoke Ethanol
List 7 inhibitors
Cimetidine Erythromycin/ Clarithromycin Ketoconazole/ Azole antifungals Fluoxetine Grapefruit HIV protease inhibitors Omeprazole
What type of metabolism is affected by old age?
Mostly cytochrome metabolism so you have to adjust dosage
What is P-glycoprotein?
Transporter which plays a role in the elimitation of xenobiotics
What do P-glycoproteins do to xenobiotics at the GI tract?
They reduce absorption by expelling them from the cells
What do P-glycoproteins do to xenobiotics at the liver and kidey?
They enhance elimination
P-glycoproteins share the same inducers and inhibitors at what mechanism?
Cytochrome P450
What would happen to the plasma concentration of xenobiotics if you induce P-glycoproteins?
Cp would decrease
What would happen to the plasma concentration of xenobiotics if you inhibit P-glycoproteins?
Cp would increase
What kind of drugs do kidneys excrete?
water soluble
non volatile
Describe glomerular filtration
drug less than 69000 MW
Rate- 120ml/min
No protein bound drug
Describe Active tubular secretion
Directly from blood to urine
120-600ml/ml
strong acids and bases in proximal tubule
Protein binding does not effect secretion half-life
Rate of tubular reabosorption
1ml/min
where does passive diffusion of the kidney occur?
Proximal and distal tubule. Weak acids or bases depends on pH of urine
Active reabsorption is important for what molecules?
Endogenous
What are the characteristics of drugs excreted via biliary and fecal excretion?
Highly water-soluble and High molecular weight
Describe enterohepatic circulation
Drug metabolised in liver
Enters bile duct
Enters GI and gets hydrolyzed back to parent drug by bacterial enzymes
Reabsorbed
What do antibiotics do to drugs that are enterohepatically recycled
Decrease plasma concentration by decrease enzyme producing bacteria
Do most drugs pass into the breast milk
Yes, but at low levels so you can ensure lowest levels by desyncronizing breastfeeding and Cmax of drug
