Pharmacokinetics

Question 1

Pharmacodynamics

Answer 1

The effects of drugs and their mechanisms of action

“the effect of the drug on the body”

Question 2

Pharmacokinetics

Answer 2

The movement of drugs through the body

“the effect of the body on the drug”

Question 3

Pharmacotherapeutics

Answer 3

The clinical (therapeutic) uses of drugs

“using drugs to treat disease”

Question 4

Therapeutic Index (ratio)

Answer 4

The amount of drug that brings about the therapeutic effect compared to the amount that causes toxicity or death

“effective dose vs. harmful dose”

Question 5

3 ways that drugs cross membranes

Answer 5

Via Channels and Pores
Via Transport Systems (P-Glycoprotein)
*Via Direct Penetration of the Membrane

Question 6

ADME

Answer 6

Absorption
Distribution
Metabolism
Excretion

Question 7

Drug Absorption

Answer 7

The movement of a drug from the site of administration into the blood

Question 8

Drug Distribution

Answer 8

Once in the blood, the movement of drugs throughout the body

Question 9

Drug Metabolism

Answer 9

Also known as biotransformation, it is the enzymatic alteration of drug structure (done, by in large, by the liver.)

Question 10

Drug Excretion

Answer 10

The removal of drugs from the body, done either by excretion into bile or urine

Question 11

Lipid Solubility

Answer 11

A measure of the ability of a drug to dissolve in water vs. lipid

• Effects membrane diffusion, ADME

Question 12

Ionization (Pka)

Answer 12

When ionized drugs are charged. Acidic drugs are ionized in basic solutions and basic drugs are ionized in acidic solutions.

• Effects rate and location of drug absorption.

Question 13

Protein Binding

Answer 13

The extent to which a drug binds to plasma proteins.

• Effects Distribution, Metabolism, and Excretion

Question 14

Bioavailability

Answer 14

The fractional extent to which a dose of drug reaches the blood stream and its site of action.

Depends greatly on several factors: physiochemical properties of the drug, route of Administration, metabolic or excretory capacity by the liver or intestines for the drug.

Question 15

first-pass effect

Answer 15

when a large percentage of the drug is metabolized by the liver, so that the concentration of a drug is greatly reduced before it reaches the systemic circulation

Question 16

oral administration (key points on absorption; advantages and disadvantages)

Answer 16

Absorption: Can is variable and depend on many factors

Pros: Most convenient and economical, often also most safe

Cons: Requires patient compliance, bioavailability can be erratic and incomplete

Question 17

Intravenous administration (key points on absorption; advantages and disadvantages)

Answer 17

Bypasses absorption,
Potential immediate effects, suitable for large volumes and irritating substances.

Pros: Valuable for emergency use, permits titration

Cons: Increased risk of adverse side effects

Question 18

Subcutaneous administration (key points on absorption; advantages and disadvantages)

Answer 18

Can be prompt or slow depending on drug preparation, can be affected by changes in blood flow to tissue

Pros: Suitable for self-administration

Cons: Not suitable for large volumes, possible pain or necrosis at site

Question 19

Intramuscular administration (key points on absorption; advantages and disadvantages)

Answer 19

Can be prompt or slow depending on drug preparation, can be affected by changes in blood flow to tissue

Pros: Suitable for self-administration

Cons: Contraindicated with anticoagulants

Question 20

Sublingual administration

Answer 20

absorbed via oral mucosa, bypasses the liver

Question 21

Transdermal administration

Answer 21

absorbed through intact skin, drugs are usually highly lipid soluble, compromised skin integrity can greatly affect absorption

Question 22

Rectal administration

Answer 22

50% of drugs absorbed via the rectum will bypass the liver, absorption however can be irregular and incomplete and some drugs may irritate the rectal mucosa

Question 23

Intra-arterial administration

Answer 23

administration requires great care, can help localize drug effects, bypasses liver

Question 24

Intrathecal administration

Answer 24

drugs administered into CSF (into spinal subarachnoid space, or into brain intraventricular space) , bypasses BBB

Question 25

Inhaled (pulmonary absorption)

Answer 25

absorbed through pulmonary epithelium and mucous membranes of the the respiratory tract, used mostly for gases and aerosolized droplets, almost instantaneous absorption, bypasses liver, and provide local application when lungs are the target

Question 26

Topical application

Answer 26

to mucous membranes (of nasopharynx, oropharynx, vagina, colon)

Question 27

Physiological factors affecting drug distribution

Answer 27

cardiac output, regional blood flow, capillary permeability, and tissue volume

Question 28

Physiochemical properties of the drug that affect drug distribution

Answer 28

lipid solubility, pH partitioning, drug binding to plasma proteins and/or tissue macromolecules

Question 29

3 other important factors in drug distribution (aside from physiological and physiochemical)

Answer 29

Fat as a drug reservoir (sequestration)
Bone sequestration
Redistribution

Question 30

Cytochrome P-450 Superfamily

Answer 30

superfamily of liver enzymes responsible for biotransformation of the vast majority of drugs

Question 31

Volume of distribution

Answer 31

the apparent space in the body available to contain the drug

Question 32

Clearance

Answer 32

the body’s efficiency in eliminating the drug from systemic circulation

Question 33

Elimination half-life

Answer 33

rate of drug removal from systemic circulation (time is takes for plasma concentration of drug to be reduced by half)

Question 34

one-compartment model

Answer 34

when the drug is distributed instantaneously into a unique compartment in the body

• characterized by a distribution volume
• The drug input into this volume depends on the dosage regimen.
• The drug output from this volume is characterized by an elimination constant rate

Question 35

two-compartment model

Answer 35

used for drugs which slowly equilibrate with the tissue compartment, e.g, vancomycin