Drug Metabolism and Excretion Flashcards
What is anoher word for “metabolism”?
Biotransformation
What is metabolism?
Body’s ability to change a drug from the form in which is was administered to a form that can be eliminated from the body.
Where can metabolism occur?
Mostly liver.
Kidney, lungs and nervous system too.
Where are fat soluble drugs eliminated?
Via the biliary system.
What can cats not produce?
Glucaronic acid.
What factors determine how a drug will be metabolised by the body?
Species
Different drugs competing for enzymes (drug interaction).
Drug tolerance
Young animals whose liver enzyme systmes are not fully developed
Elderly animals whose enzyme systems have a decreased ability
What is excretion?
When the body eliminates a drug
Where are most drugs eliminated from the body?
In urine via the kidneys
What are several other routes of excretion?
Lungs, intestinal tract, sweat glands, salivary glands, skin, mammary glands
What improves drug excretion from the kidney?
Renal perfusion
What is ‘glomerular filtration’?
When the glomerulus (network of capillaries in kidney nephron) filters drug molecules out of the blood passing them to the glomerular filtrate where they can be excreted in urine.
What is ‘tubular secretion’?
When the kidney tubule secretes water soluble metabolites out of the network of capillaries surrounding the tubule into the glomerular filtrate where it is excreted in urine.
How does the liver excrete drugs.
1 - incorporates drug in to bile
2 - bile passed to small intestine (active transport required as moving across biliary epithelium against a concentration gradient)
3 - from small intestine in to faeces or reabsorbed in to blood stream
