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1

What are the mechanisms of drug permeation?

1. aqueous diffusion (paracellular)

2. lipid diffusion (trancellular)

3. special carriers

4. endo and exocytosis

2

What is absorption when it comes to drugs?

transfer of a drug from its site of administration to the bloodstream

3

What form is complete absorption or delivery

IV

4

Explain the oral route of drugs

most convenient; absorption may be slower and less complete

suffers from first-pass effect (must go through gut wall and liver)

5

What are the enteral routes of drugs?

sublingual- by pass first-pass effect

rectal - partial avoidance

6

What are the paraenteral routes?

intravenous

intramuscular

subcutaneous

intradermal

7

What are other routes of drug administration?

oral inhalation

nasal inhalation

topical

transdermal

8

What factors influence drug absorption?

1. pH
2. surface area
3. blood flow to desired site
4. contact time
5. P-glycoprotein

9

What are most drugs?

either weak acids or weak bases

10

What is the effect pH has on drug absorption?

The protonated form of a weak acid is the more liposoluble form

The unprotonated form of a weak base is the more liposoluble form

11

What kinds of drugs are excreted faster?

Weak acids are excreted faster in alkaline urine; weak bases are excreted faster in acidic urine.

12

Where does most drug absorption occur?

the small intestine bc of the large surface area

13

What is P-glycoprotein?

it is a transporter protein that is used to transport drugs across the cell membrane

reduces drug absorption

14

what is bioavailability?

Fraction of administered dose of a drug that
reaches the systemic circulation

15

how is bioavailability measured?

Bioavailability is determined comparing the AUC
after a particular route of administration with the
AUC after IV injection.

the area under the curve reflects the extent of absorption.

16

What is drug distribution

It is the process by which a drug leaves the
blood stream and enters the extracellular fluid
and /or the cells of the tissues

17

what affects drug distention?

blood flow

drug binding

capillary permeability

drug hydrophobicity

18

What kinds of drugs can enter the CNS?

highly liposoluable or have an active transporter

19

How does drug elimination occur?

metabolism and excretion

20

How does metabolism lead to drug elimination?

many drugs are lipophilic and are not easily excreted

drugs are broken down into hydrophilic compounds which ends biological activity and elimination from the body.

21

What enzymes are responsible for the metabolism of 80 percent of all drugs used?

cytochrome P450 system

22

What drugs increases the synthesis of one or more P450 isoforms?

rifampin

phenobarbital

carbamazepine

23

what are xenobiotic receptors?

They help regulate the transcriptional activation of genes

24

What are the clinical consequences of enzyme induction?

A drug can increase its own metabolism

A drug can increase the metabolism of a coadministered drug.

This may reduce drug plasma concentrations below therapeutic levels

25

What are drugs that inhibit cytochromes P450?

• Cimetidine
• Erythromycin
• Chloramphenicol
• Grapefruit juice

26

What is the most common form of drug elimination?

renal excretion