Basics and Drug Absorption

Question 1

Chirality affects duration of drug action

Answer 1

Enzymes are stereoselective, will prefer one enantiomer over the other, the form without the best fit will have a longer duration of action

Question 2

Two effects of drug binding to a receptor

Answer 2

Agonist- drug binds to receptor and stimulates cellular activity
Antagonist- drug binds to receptor and inhibits action of agonists

Question 3

Actions of drugs not working through receptors

Answer 3

Include chemical antagonists, physiologic antagonists, osmotic agents, and DNA drugs

Question 4

Pharmacodynamics

Answer 4

Actions of a drug on the body

Question 5

Pharmacokinetics

Answer 5

Actions of the body on the drug

Question 6

Selectivity of enzymes/receptors for racemic states

Answer 6

Drugs are chiral, enzymes are usually stereoselective, drugs are racemic mixtures, one form may be inactive or potentially harmful

Question 7

Warfarin

Answer 7

Given as a racemic mixture, S enantiomer is more potent than R

Question 8

Fast vs. slow acetylators

Answer 8

Affects rate at which isoniazid is metabolized, slow acetylators have 4-6x blood concentrations of given dose than fast acetylators, drug stays active and unmetabolized longer, duration of action is longer

Question 9

Advantages of prolonged-release drugs

Answer 9

Less frequent administration, therapeutic effect overnight, fever/less severe side effects, easier patient compliance

Question 10

Mechanism of action

Answer 10

How a drug works, includes site where it acts and mechanism by which it produces effects

Question 11

Side effect vs. contraindication

Answer 11

Side effects- undesired effects of the drugs
Contraindications- conditions that prevent the safe use of a drug, co-administering with other drugs may produce undesirable effects

Question 12

Enteral drug administration

Answer 12

Drug given into the GI tract, limited by absorption from GI tract, inactivation by digestive enzymes, clinical conditions (vomiting, unconsciousness), blood flow, surface area

Question 13

Parenteral drug administration

Answer 13

Administration by means other than GI tract, usually injection

Question 14

Target concentration

Answer 14

Target drug concentration in the plasma, desired concentration the physician wants to produce therapeutic effects

Question 15

Steady state concentration

Answer 15

Drug in equals drug out

Question 16

Oral drug administration (PO)

Answer 16

Most common enteral and usually convenient, absorption from GI tract, limited by first pass effect, lack of absorption, inactivation by digestive enzymes, vomiting, unconsciousness, blood flow, surface area

Question 17

Sublingual drug administration (SL)

Answer 17

Enteral, oral mucosa provides good absorption into systemic circulation

Question 18

Buccal drug administration

Answer 18

Enteral, between tongue and cheek, absorbs into systemic circulation

Question 19

Rectal drug administration (PR)

Answer 19

Enteral, suppositories, fairly good absorption, good for vomiting or unconscious patient, 50% of drug absorbed with bypass the liver, disadvantages include irregular absorption and rectal irritation

Question 20

Intravenous (IV)

Answer 20

Parenteral, directly into vein, no absorption, rapid high levels, dose titration (anesthesia)

Question 21

Intraarterial (IA)

Answer 21

Parenteral, uncommon, some diagnostic and anticancer agents, requires skilled personnel

Question 22

Intramuscular (IM)

Answer 22

Parenteral, injection into skeletal muscle provides good absorption, rate is dependent on drug form and solubility

Question 23

Epidural (EPI)

Answer 23

Parenteral, injection into epidural space, used in procedures requiring spinal analgesia

Question 24

Intraperitoneal (IP)

Answer 24

Parenteral, into IP cavity, not often used due to risk of infection and adhesions, very painful

Question 25

Topical

Answer 25

Parenteral, percutaneous absorption, localized action absorbed through intact skin

Question 26

Inhalation

Answer 26

Parenteral, drug can be delivered to target organ in respiratory diseases, lungs have large surface area, good absorption, rapid onset, short duration

Question 27

Bioavailability

Answer 27

Fraction or % of administered drug that reaches the systemic circulation via a given route, F=1 for IV administration

Question 28

Amount of drug reaching circulation

Answer 28

Equal to bioavailability (F) x dose given

Question 29

Dose of new form of drug

Answer 29

Equal to (dose x F of the current form) / F of new form

Question 30

Minimal effective concentration (MEC)

Answer 30

Threshold plasma concentration, enough drug is present to enter tissues, interact with receptors, produce an effect, measure of drug activity