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Flashcards in General Principles of Pharmacology II Deck (13)
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1
Q

Where does biotransformation of drugs occur?

A

Primarily in the liver

Can also occur in kidney, lung, nerve tissue, plasma, or GI tract

2
Q

What are the results of biotransformation?

A

Active -> inactive

Inactive -> active

Convert active drug to active metabolite

Convert active drug to toxic metabolite

3
Q

What is a metabolite?

A

Product of biotransformation of a drug

Generally more polar, more water soluble, and excreted faster than parent drug

4
Q

What are general classes of biotransformation reactions?

A

Phase I - Oxidation, reduction, hydrolysis

Phase II - Conjugation

5
Q

What are microsomal enzymes?

A

Located in SER

Oxidative enzymes known as mixed function oxidases (MFO)

Cyt P450 is the terminal oxidase of MFO

Require substrates to be lipid soluble

Activity is inducible

6
Q

What is the danger of taking acetaminophen after drinking alcohol?

A

Ethanol activated 2E1 enzyme which is responsible for converting acetaminophen to a toxic metabolite

7
Q

What is the most common conjugation reaction in the body?

A

Glucuronide formation

8
Q

What are non-microsomal enzymes?

A

Located in cytosol and mitochondria

Non-inducible

9
Q

What factors affect the rate of biotransformation?

A

Enzyme inducers and inhibitors

Age

Liver function/disease

Nutritional State

Genetics

Gender

10
Q

What are the primary routes of drug excretion?

A

Biliary and renal

Other routes include sweat, saliva, breast milk and exhalation

11
Q

What generally determines whether a drug undergoes biliary excretion or urinary excretion?

A

Molecular weight

> 300 -> biliary

12
Q

What is enterohepatic cycling?

A

If a drug has a favorable partition coefficient for reabsorption in the GI tract, then it will be reabsorbed and returned to the liver, where it will be excreted again in the bile

13
Q

What three processes occur in renal excretion of drugs?

A

Filtration through glomerulus

Non-ionic back diffusion in distal portion (weak acids are prononated and unionized)

Active transport of anionic and cationic forms of drugs in the proximal portion of the nephron