8-7 Clinical Pharmacokinetics

Question 1

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Answer 1

A: Bioavailability for drugs taken PO are typically less than 100% due to absorption discrepancies and [1st pass effect metabolisms]

B: drug that has low protein binding —> HIGH Vd! This is because it’ll take more plasma to get 100% of the original dose back if the drug is readily distributing into tissues unbound to plasma proteins.
B2: Medications with DEC protein binding have INC [Blood Brain Barrier] crossing

Question 2

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Answer 2

Metabolism in the Liver:

Phase 1= Reduction / Oxidation and hydrolysis of a drug (to add a functional group) by the Cytochrome P450 family. Phase 1 is the most common phase associated with drug-to-drug interactions. Drugs fight for Cytochrome P450

Phase 2 = Conjugation of Drug to further improve hydrophilicity [Sulfation / Glucuronidation / Acetylation]

[Smoking & Alcohol INC Liver Enzymes and therefore inactivates drugs]

Question 3

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Answer 3

A: Creatinine is used to estimate renal function BUT keep in mind that renal function deteriorates with age!

B: Creatinine also comes from muscle. So…Elderly people have less muscle and therefore will have lower serum levels of Creatinine off bat. This will cause Docs to OVERestimate renal function and believe renal function is better than it is.

C: Burn pts develop low Albumin—> INC Volume of Distribution of the Drug