Introduction to Pharm

Question 1

Pharmacogenetics

Answer 1

Genetic influences by and on drugs

Question 2

Pharmacodynamics

Answer 2

Physiological and biochemical mechanism of action of drugs (what the drug does to the body)

Question 3

Competitive vs noncompetitive drug binding

Answer 3

Competitive: Reversible, most drugs
Noncompetitive: Nonreversible (ex: Aspirin)

Question 4

ED50

Answer 4

Effective dose in 50% of the population

Question 5

TD50

Answer 5

Toxic dose in 50% of the population

Question 6

LD50

Answer 6

Lethal dose in 50% of the population

Question 7

LD50/ED50

Answer 7

Therapeutic index

• Safety measure of drug
• Higher number = better

Question 8

TD50/ED50

Answer 8

Therapeutic window

• Estimation of drug dose that can treat disease effectively while staying in safety range (minimal toxicity/side effects)
• Ratio between minimum effective concentration to minimum toxic concentration
• “Margin of safety”

Question 9

Strongest chemical bond type -> weakest (5 of them)

Answer 9

Covalent, usually is irreversible

Then ionic, hydrogen, hydrophobic, van der waals

Question 10

4 things a dose response curve lets your determine

Answer 10

Affinity/potency 
-How much drug is needed/attraction of drug to receptor
Efficacy
-Can the drug produce 100% of the desired effect?
Variability
-Difference in living things
Slope
-Measures the margin of safety/toxicity

Question 11

ED99

Answer 11

Effective dose in 99% of the population

Question 12

Down-regulation

Answer 12

Caused by continued stimulation of cells with agonists, leads to desensitization
-Effect that follows continues or subsequent exposure to the same concentration of drug is diminished

Question 13

Up-regulation

Answer 13

Caused by chronic administration of antagonists

• Number and sensitivity of receptors increase when they’re chronically blocked
• Results in tolerance-higher doses of antagonist are needed to counteract increasing receptor number

Question 14

Addition effect of drugs

Answer 14

Combined effect of 2 drugs via the same mechanism is equal to what’s expected by adding their individual actions (1+1=2)

Question 15

Synergism effect of drugs

Answer 15

The combined effect of 2 drugs is greater than the algebraic sum of their individual effects (1+1=3)

Question 16

Potentiation effect of drugs

Answer 16

The enhancement of the action of one drug by a second drug that has no detectable action of its own (1+0=3)

Question 17

Antagonism effect of drugs

Answer 17

The action of one drug opposes the action of another (1+1=0)

-Reversal drugs

Question 18

Bioavailability definition in drug administration

Answer 18

The percentage of drug contained in a drug product that enters the systemic circulation in an unchanged form after administration of the product

• IV: 100%
• Inhalation: 5-<100%
• Oral: 5-<100%, first-pass effect may be significant

Question 19

pKa

Answer 19

Ionization constant of a chemical compound, pH at with the drug will exist in solution as 50% ionized and 50% non-ionized
-Measures the extent of ionization (not acid/base status)

Question 20

General absorption of non-ionized drug

Answer 20

• Lipid soluble
• Can be absorbed through GI
• Can cross placenta and blood brain barrier

Question 21

General absorption of ionized drug

Answer 21

• Water soluble

- Can’t get through phospholipid bilayer to be absorbed GI/placenta/BBB

Question 22

pH-pKa=0

Answer 22

50/50 ionized/non-ionized

Question 23

pH-pKa=0.5

Answer 23

75/25 ionized/non-ionized

Question 24

pH-pKa>1

Answer 24

99/1 ionized/non-ionzed

Question 25

Determining ionized vs nonionized percentage

Answer 25

Acids
-In acidic pH: Non-ionized
-In basic pH: Ionized
Bases
-In acidic pH: Ionized
-In basic pH: Non-ionized

Question 26

Drug metabolism: Phase 1 vs 2 reactions

Answer 26

Phase 1
-Oxidation
-Reduction
-Hydrolysis
Phase 2
-Conjugation
-Synthesis

Question 27

Conjugation metabolism

Answer 27

Coupling the drug molecule to an endogenous substituent group so it has more water solubility

• Leads to enhanced renal or biliary elimination
• Catalyzed by phase 2 drug-metabolizing enzymes

Question 28

1st pass metabolism (and effect of grapefruit juice)

Answer 28

After the oral administration of a drug

• Absorbed drugs to go liver before systemic circulation
• Decreases their bioavailability
• Grapefruit juice inhibits CYP3A enzymes-increases the bioavailability of the drug

Question 29

Enzyme induction and inhibition

Answer 29

Induction
-Process when drugs, environmental chemicals, air pollutants, and components of cigarette smoke stimulate the synthesis of drug-metabolizing enzymes
-May elevate the level of hepatic drug-metabolizing enzymes
Inhibition
-Opposite of ^
-Results in less metabolism of drugs, increasing their effects

Question 30

Ionized drugs that are taken orally (metabolism)

Answer 30

Not absorbed well, may not be metabolized by the liver to a significant extent
-Instead are commonly excreted via the renal system

Question 31

Main factors (2) that determine the rate of drug passive diffusional transfer across membranes

Answer 31

Lipid solubility of the drug
Concentration gradient
(Molecular weight is less important than ^)

Question 32

Protein binding (bond strength, proteins, examples where its significant)

Answer 32

• Influences how a drug is distributed
• Protein-bound drug isn’t free to act on receptors
• Proportional to its lipid solubility (more lipid soluble=highly protein bound)
• Bond between drug and protein is usually weak
• Proteins=albumin (most common), AAG
• > 90% protein bound drugs=warfarin, phenytoin, propranolol, Propofol, fentanyl, diazepam (intensification of their effects if they’re displaced from plasma proteins)

Question 33

Beta half-life

Answer 33

AKA Elimination half-life

• Time necessary for the plasma content of a drug to drop by half
• Drug is fully eliminated when 95% of it has been eliminated from the body (4-5 half-lives)