Drug Metabolism Flashcards
What is the purpose of drug metabolism?
to eliminate a drug
What would happen if drug metabolism did not occur?
there would be prolonged uncontrolled activity of a given drug
Ex: Thiopental could be active for about 100 years
Where does most drug metabolism occur?
the liver - hepatic microsomes in the smooth ER
What is the role of the kidney in drug metabolism?
to eliminate the drug from the system
What is the goal of drug metabolism?
to polarize the active lipoidal drug so that it can be eliminated from the kidneys
In what state are most active drugs?
lipidoidal and non-polar so that they can cross the membrane
How can renal reabsorption be circumvented for non-polar drugs?
active secretion
What is the predominating biochemical reaction for Phase II drug metabolism?
glucuronidation
What species are poor at glucuronidation?
cats and polar bears
What are the 4 possible outcomes of biotransformation?
- Active drug to inactive metabolite
- Active drug to active metabolite to inactive metabolite
- Inactive drug (pro-drug) to active metabolite to inactive metabolite
- Active drug to toxic metabolite
What is the first-pass effect?
when some of a drug gets metabolized before reaching the systemic circulation
What two organs are involved in the first-pass effect?
the intestines and the liver
What drugs is the first-pass effect important in?
oral drugs and drugs given intraperitoneally
How do you avoid the first-pass effect?
give more orally or give via an alternative route
Why are herbivores better at metabolizing drugs than carnivores?
because they are exposed to more plant compounds therefore they are more efficient at metabolizing drugs
