Pharmacology

Question 1

Drugs

Answer 1

chemical that produces a change in the body

Question 2

Selectivity

Answer 2

determined by receptors affinity for binding, which also determines drug concentration to produce desired effect
*factors include: chemical nature, dose, route, genetic make-up, underlying disease, age, etc

Question 3

Risk-Benefit ratio

Answer 3

safe, appropriate and economical use of drugs to treat disease

Question 4

Affinity/potency

Answer 4

Affinity- how well the drug binds to the receptor

Potency- the amount of drug needed to produce an effect that is 50% of the maximum

Question 5

efficacy

Answer 5

maximal response that can be achieved by a drug Ecmax

Question 6

agonist (partial agonist)

Answer 6

drug interaction with a receptor to elicit a response (activates receptors by mimicking endogenous ligand
-partial: for the same dose as full, only produces part of the response

Question 7

antagonist

Answer 7

drug interaction with a receptor to inhibit a response

• competitive: competes for same binding site
• non-competitive: binds to allosteric site
• irreversible: effects cannot be undone until enzyme is metabolized
• physiologic: two molecules have opposite effects that are mediated through diff. mechanism (ex histamine as vasodilator and epi as constrictor)
• chemical: antagonist removes the drug being antagonized to inhibit its ability to reach the target

Question 8

therapeutic index

Answer 8

how selective a drug is in producing its desired effects v. its adverse effects
TD50/ ED50
(dose for toxicity over dose for desired result)
the higher the safer

Question 9

What are the molecular targets for drugs?

Answer 9

Receptors, ion channels, enzymes

immediate target for most drugs

Question 10

G protein- cellular action

Answer 10

link drug to target

Question 11

oral

Answer 11

most common

advantages: convenient, cheap, variety
disadvantages: sometimes inefficient, first pass effect (partial absorption)

Question 12

first pass metabolism

Answer 12

from duodenum to liver then to general circulation
can be activated by liver metabolism or inactivated
ie biotransformation effecting bioavailability

Question 13

sublingual

Answer 13

advantages: avoids first pass, rapid access to circulation, stability (neutral pH in mouth)
disadvantages: inconvenient, small doses

Question 14

rectal

Answer 14

advantages: 50% bypass liver, prevent destruction though GI, good for kids or other pts unable to take drugs orally
disadvantages: erratic absorption and often incomplete, social stigma

Question 15

parenteral

Answer 15

used for drugs not good in GI, unconscious patients

advantages: rapid onset, provides most control over actual dose

Question 16

intravascular

Answer 16

advantages: rapid, total dose bioavailability
disadvantages: toxic, trained personnel, expensive

Question 17

intramuscular

Answer 17

advantages: fast or slow release form
disadvantages: trained personnel

Question 18

subcutaneous

Answer 18

advantages: self-admin, slow but complete absorption
disadvantages: apin, irritant, low dose (2ml)

Question 19

inhalation

Answer 19

rapid, convenient, and effective if lung is the target

Question 20

intranasal

Answer 20

systemic effects, easy, good compliance, bypass first pass

Question 21

topical

Answer 21

local effects (but absorption through skin cuts or abrasions can be substantial)

Question 22

transdermal

Answer 22

advantage: systemic effect, controlled release
disadvantage: for only small molecules

Question 23

Absorption- factors affecting it?

Answer 23

size- smalle, uncharged = better
pH- acidic drugs ionized at basic pH (& vice versa)
lipid solubility- partition coefficient greater= greater solubility in lipid
gastric emptying

Question 24

Distribution- factors affecting it?

Answer 24

• size- small
• plasma protein binding- albumin binds to drugs
• permeability of membrane= capillaries very permeable whereas CNS only allows extremely hydrophobic molecules to pass
• volume of distribution- amount of drug in body at a time

Question 25

Metabolism- role of phase 1 and 2? type of rxns?

Answer 25

phase 1: oxidative (some hydrolytic, reductive)
pro-drugs BIOTRANSFORMATION

phase 2: conjugate reaction (acetate, glucuronate, sulphate, or glycine)
IV EXCRETION