Principles of Pharmacology

Question 1

Pharmacokinetics

Answer 1

What the body does to the drug

How the drug concentration in the plasma changes over time

Question 2

Pharmacodynamics

Answer 2

what the drug does to the body

relationship between drug concentration and its biological effect

Question 3

ADME

Answer 3

Absorption
Distribution
Metabolism
Excretion (Elimination)

Question 4

Excipients

Answer 4

non-medicinal ingredients such as fillers, antioxidants, disintegrants, colorants and coatings, flavourants and sweeteners

Question 5

Enteral Administration (PO)

Answer 5

entry of drug through the gastrointestinal (GI) tract (per os - orally, or anally)

cannot administer acid-sensitive or protein drugs PO

Question 6

Parenteral Administration

Answer 6

not by the GI tract (colloquially injection)

bypasses the liver, avoids first pass effect

Question 7

Absorption

Answer 7

entry of drug into circulatory system

moves from the external environment to the internal environment

Question 8

First Pass Metabolism (and consequences)

Answer 8

most drugs given orally first pass through the liver before entering the systemic circulation

Drug concentration can drop dramatically when given PO

Question 9

Sublingual (SL)

Answer 9

dissolved under the tongue

rapid absorption, can give acid-sensitive drugs this way

NO first pass effect (directly into bloodstream)

Question 10

Subcutaneous (SC)

Answer 10

beneath the skin

local drug delivery, but requires sterile drug

Question 11

Intramuscular (IM)

Answer 11

injected into muscle

fast but somewhat painful

Question 12

Intravenous (IV)

Answer 12

Directly into vein

rapid bolus (IV push) or as a continuous infusion (IV drip)

Question 13

Inhalation

Answer 13

gasses or gas mixtures, particulate powders, nebulized (mist)

Question 14

Topical Routes

Answer 14

Skin
Eyes (drops – gtt [Latin guttae])
Ears
Nose
Vagina

Question 15

Skin administration

Answer 15

no first pass effect

must be lipid-soluble

creams, gels, ointments, patches, sprays

Question 16

Other routes:

intra-articular injection 
intra-cardiac injection 
epidural injection
spinal injection 
buccal

Answer 16

joints
heart
very close to spinal cord
into spinal fluid
absorption between gum & cheek

Question 17

Most drugs are absorbed: actively or passively?

Answer 17

passively

Question 18

Chemical Factors Affecting Drug Absorption (3)

Answer 18

1. Drug size (molecular, how many atoms)
2. Lipid solubility (passes through membranes more easily)
3. Drug charge (more charged = less lipid soluble)

Question 19

Physical Factors Affecting Drug Absorption (4)

Answer 19

1. Blood flow to the site of absorption (faster blood = more quickly removed from site of administration)
2. Total surface area of site (Higher the surface area, the quicker/better the absorption)
3. Contact time with site of absorption
4. Drug formulation (dissolve speed)

Question 20

Bioavailability

Answer 20

the proportion of drug that passes into the systemic circulation after administration, taking into account both absorption and local metabolic degradation

Question 21

Insulin route of administration?

Answer 21

injected (subcutaneous because it’s a protein)

Question 22

Distribution Factors (3)

Answer 22

Blood flow to tissues
Exiting the vascular system
Entering cells

e.g.
rapid distribution: heart, liver, kidneys, brain
slow distribution: muscle, skin, fat

Question 23

Plasma Protein Binding

Answer 23

albumin transports fat soluble molecules around the blood

bound molecules cannot leave bloodstream

most drugs are bound to plasma proteins, are not free-floating

liver creates albumin, so there are more free molecules in a person with liver disease

Question 24

Metabolism (what is it?)

Answer 24

Modification (change) of drug molecule by cell enzymes

mostly occurs in the liver by the cytochrome P450 enzymes

Question 25

Consequences of Metabolism

Answer 25

Accelerated renal drug excretion

Drug inactivation

Increased therapeutic action

Activation of prodrugs

Increased or decreased toxicity

Question 26

Grapefruit Juice

Answer 26

affects metabolism by inhibiting CYP enzymes

Question 27

Excretion

Answer 27

occurs mostly through the kidneys

nephrons are the functional unit of the kidney

most drugs must be metabolized first (made more water-soluble) in order to be excreted

Question 28

Duration of effects is determined largely by the combination of:

Answer 28

metabolism and excretion

Question 29

Half-life

Answer 29

the time required for the amount of drug in the body to decrease by 50%

a measure of the rate at which drugs are removed from the body

Question 30

Steady State

Answer 30

When there is a consistent level of drug in the body

dependent on the drug’s half-life

reached after 4-5 half-lives
e.g. drug half-life is 4 hours: 4x4 = 16, 4x5 = 20 so approx. 18 hours to reach steady state

Question 31

Agonist

Answer 31

elicits a response in the receptor of the cell

Question 32

Antagonist

Answer 32

prevents a response to an endogenous agonist

Question 33

Onset

Answer 33

time it takes for the drug to elicit a therapeutic response

Question 34

Peak

Answer 34

time it takes for a drug to reach its maximum therapeutic response

consider MEC – Minimum Effective Concentration

Question 35

Therapeutic index

Answer 35

Ratio of the drug’s toxic to effective blood concentration

The larger/higher the therapeutic index, the safer the drug

The smaller/lower the therapeutic index, the less safe the drug