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Flashcards in Intro to Pharmacokinetics Deck (22)
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1

ADME

Absorption
Distribution
Metabolism
Elimination

2

Pharmacodynamics

how the drugs affect the body

3

Pharmacokinetics

how the body affects/handles the drug

4

Pharmacokinetic calculations needed for...

1. concentration dependent efficacy/toxicity
2. Narrow therapeutic index

5

Absorption

Passive
- ionized (eliminated) v. unionized (re/absorbed)
Active absorption/transport (and carrier mediated)
1. ENERGY REQUIRING
2. Saturable - competitive inhibition by other meds
3. Movement against gradients - electrochemical and concentration gradients

6

Lipid solubility in ionized v. unionized

Ionized - Lower lipid solubility = do not easily diffuse across lipid bi-layer membranes
Unionized - higher lipid solubility = easily diffuse across lipid bi-layer membranes

7

Ionization status depends on 2 factors

1. pKa of med
2. pH of membrane gradient

When pKa=pH; 50:50 ratio of ionized:unionized

8

2 body systems where pH varies and commonly impacts ionization status

GI tract
Kidneys

9

Protein binding: bound v. unbound

bound = inactive
UNBOUND = ACTIVE

10

alpha (small v. large)

unbound fraction
small alpha = less unbound

11

Phase 1 Reaction

Metabolism - alters functional groups (oxidation, reduction, hydrolysis)

12

Phase 2 Reaction

Metabolism - alters covalent linkages (glucuronidation, sulfation, acetylation)

13

Cytochrome P450 Enzyme System

Main sites: liver, GI, Brain, Kidney

14

CYP450 enzyme inducers

carbamazepine
phenytoin
phenobarbital
isoniazid

15

CYP450 enzyme inhibitors

fluoxetine
omeprazole
cimetidine

16

First pass metabolism

determines oral administration v. IV
liver metabolizes

17

Elimination via liver and kidneys:

lungs, sweat, bile/feces

18

REduced renal or hepatic function may result in ____ in dose

change

19

3 main processes of Renal Elimination

1. Passive GF
2. Passive tubular diffusion
3. Active tubular secretion

20

Passive GF

blood flow dependent

21

Passive tubular diffusion

PcT, DcT
ionization and concentraiton status dependent

22

Active Tubular secretion

weak acids/bases secreted into PcT