Chapter 9. Pharmacokinetic and Toxicokinetic Principles Flashcards Preview

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Flashcards in Chapter 9. Pharmacokinetic and Toxicokinetic Principles Deck (16):
1

Difference between pharmacokinetics and toxicokinetics?

Pharmacokinetics is study of absorption, distribution, metabolism, elimination of xenobiotics. Toxicokinetics is study of absorption, distribution, metabolism, elimination of xenobiotic producing toxicity

2

What is first-pass effect?

Metabolism before the xenobiotic reaches the blood.

3

How does membrane thickness effect simple diffusion?

Membrane thickness (h) is inversely proportional to rate of diffusion. (Fick's Law of Diffusion)

4

When pH = pKa, what proportion of xenbiotic is charged/uncharged?

When pH = pKA then xenobiotic is in 1:1 ration charged/uncharged

5

If pH

Uncharged. Diffuses more readily across membranes.

6

Thallium and lead use active endogenous transport mechanisms by resembling which electrolytes?

Thallium - potassium
Lead - calcium

7

Inhibitors of P-glycoprotein

Amiodarone, ketoconazole, quinidine, verapamil

8

Inducers of P-glycoprotein

St. John's Wort, rifampin

9

Substrates of P-glycoprotein

digoxin, protease inhibitors, vinca alkaloids, and paclitaxel

10

Site of accumulation of following: lead, DDT, carbon monoxide, and paraquat?

Lead - bone
DDT - fat
CO - hemoglobin
Paraquat - type ll alveolar cells

11

What is concern for phenytoin dosing in malnourished patient?

Phenytoin is 90% bound to albumin. If malnourished then decreased albumin available - results in greater free concentration of phenytoin.

12

In setting of salicylate overdose, how does saturation of protein binding effect Vd?

Volume of distribution will increase and salicylate levels will increase in CNS

13

CYP-2D6

Genetic variations - rapid or slow metabolizers. Codeine.

14

Difference between first order and zero order kinetics?

First order - constant percentage of drug
Zero order - constant level of drug

15

CYP associated with cancer?

CYP 1A2 & CYP 2E1

16

Michaelis-Menten

Saturable. At high concentrations - zero order kinetics dominate then switches to 1st order.