Test one: General Principles

Question 0

What is the strongest and least desirable drug binding force?

Answer 0

Covalent bonds–irreversible (aspirin)

Question 1

What are the 3 major subdivisions of pharmacology?

Answer 1

Pharmacodynamics (mechanisms of drug action), pharmacokinetics, and pharmacotherapeutics

Question 2

Assumptions of the occupation theory

Answer 2

• One molecule reversibly combines with a single receptor
• The binding is independent of other drug-receptor interactions
• The receptors are identical and equally accessible to the drug
• Only a small portion of the total drug is involved in the formation of complex with the receptor
• The biologic response is proportional to the degree of receptor occupancy and independent of time.

Question 3

Exceptions to the occupation theory

Answer 3

some receptors have subclasses
some receptors can be desensitized
some receptors give a different response based on the type of tissue that they are in.
some receptors may require cooperative interactions of ligands before they give a response, or the amount of response is determined by how many ligands are bound to them.

Question 4

What type of antagonist has affinity but not intrinsic activity?

Answer 4

Pharmacological antagonist (competitive/reversible or noncompetitive/irreversible)

Question 5

What is the definition of an inverse agonist?

Answer 5

Elicits the opposite response as the agonist

Question 6

What is the problem with IV route of administration?

Answer 6

Compliance (difficult to get an iv to take drug) and solubility (some drugs aren’t soluble); also difficult to remove from system

Question 7

How does a non-competitive antagonist bind to a receptor?

Answer 7

Covalently–irreversibly

Question 8

What is the difference between a competitive and non competitive antagonist?

Answer 8

Competetive shifts the dose response curve of the agonist to the right. Non-competitive will prevent the agonist from reaching the max response regardless of dose (SHIFTS RIGHT AND DOWN)

Question 9

What are the 4 aspects of pharmacokinetics?

Answer 9

Absorption, distribution, metabolism/biotransformation, excretion

Question 10

Where are weakly acidic drugs absorbed?

Answer 10

Stomach–environment with lower pH than its pKa to shift it to its nonpolar/lipid soluble form

Question 11

Where are weakly basic drugs absorbed?

Answer 11

Small intestines

Question 12

Chemical equivalence

Answer 12

Two or more drugs with equivalent amounts of the same active ingredient

Question 13

What is bioavailability/bioequivalence?

Answer 13

Rate and extent of drug absorption, two formulations produce similar concentrations of a drug in blood and tissue (same area under curve)

Question 14

Absolute bioavailability

Answer 14

Comparing a dosage form of bioavailability to that of iv–area under curve/dose

Question 15

Relative bioavailability

Answer 15

Comparing two different forms of dosage

Question 16

Therapeutic equivalence

Answer 16

Drugs that produce the same efficacy and toxicity in identical dosage forms

Question 17

What are the 3 types of bio transformation?

Answer 17

Hepatic microsomal metabolism, hepatic non microsomal, and non hepatic metabolism

Question 18

Volume of distribution (Vd)

Answer 18

The amount of water by which a particular dose of a drug would have been diluted to produce a given plasma concentration

Vd=Q/C, Q is quantity of drug administered and C is plasma concentration

Question 19

What does a high Vd mean?

Answer 19

The drug is more diluted in plasma than it should be (more of it is in tissue)

Question 20

What is the distribution of water in the body?

Answer 20

3L in plasma, 9L in interstitial fluid, 29L in intracellular fluid

Question 21

How is Vd affected by liver/renal failure?

Answer 21

It increases due to fluid retention. Vd decreases in dehydration.

Question 22

Why do highly lipid soluble drugs cause a metallic taste in the mouth?

Answer 22

Lipid soluble drugs have higher Vd and distribute to the saliva more easily

Question 23

What are the phases in microsomal metabolism?

Answer 23

Phase one- nonsynthetic. Cp450 increases the polarity of the drug to make it more water soluble for eventual excretion. Typically happens via oxidation (reduction, hydrolysis, dehalogenation, and dealkylation are other options)

Phase two-synthetic: drug combines with glucuronic acid to further the polarity for excretion

Question 24

What factors can affect biotransformation?

Answer 24

Delivery/entry in to the liver, enzyme inhibitors, enzyme inducers, age (very young or old), genetics, pathology

Question 25

First pass drug biotransformation

Answer 25

Drug is absorbed from digestive system to enter portal system–>metabolized by liver so that only a small amount of active drug actually enters circulation. Avoid by iv administration

Question 26

CYP1A1/2: substrate, inhibitor, and inducer

Answer 26

Substrate: acetaminophen/Tylenol
Inhibitor: cimetidine/Tagamet
Inducer: omniprazol

Question 27

Enterohepatic cycling

Answer 27

Metabolism of drug in liver, excreted into bile into intestinal lumen, drug is reabsorbed by intestinal mucosa to reenter liver–this causes peaks and a longer half life in plasma (ie: morphine)

Question 28

CYP-2A6: substrate, inhibitor, and inducer

Answer 28

Substrate: acetaminophen/Tylenol
Inhibitor: pilocarpine
Inducer: barbiturates

Question 29

Does induction of microsomal enzymes increase or decrease acetaminophen toxicity?

Answer 29

Drugs that are inducers will increase its toxicity

Question 30

What form of the drug is filtered into the glomerulus?

Answer 30

Free floating drugs–not bound to plasma protein

Question 31

In what state can drug metabolites be reabsorbed?

Answer 31

Nonpolar

Question 32

Clearance=

Answer 32

CL=U*V/P (amount of drug removed by kidney per unit of time)

U=urine concentration
V=urine volume
P=plasma concentration

Question 33

How are clearance and distribution related?

Answer 33

CL= Ke*Vd, Ke= elimination rate constant

Question 34

Zero order elimination kinetics

Answer 34

Dc/dt= Ko

Drug elimination is independent to concentration of drug; elimination is constant over time (ie:ethanol)

Question 35

How is first order kinetics different than zero order?

Answer 35

Rate of metabolism is proportional to drug concentration. There is a constant fractional rate of metabolism dc/dt=Kc

Question 36

How do you calculate half life of a first order reaction?

Answer 36

T1/2= 0.693/K

Question 37

The single compartment model is based in what type of kinetics?

Answer 37

First order; body is displayed as one compartment with it’s size corresponding to Vd; helps with constructing theoretical plasma curves where dose, absorption, and elimination can be altered to see change in concentration and effect

Question 38

What drugs follow the two compartment model?

Answer 38

Lipophilic drugs

Question 39

What are the compartments in the two compartment model?

Answer 39

Drug initially entered into central compartment where it undergoes rapid metabolism. Drug can also be distributed to peripheral tissue/fat where it is released slowly

Question 40

Tachyphylaxis

Answer 40

Drop in response to a drug/resistance; more of the drug is needed to achieve same response (ie: Afrin)

Question 41

How do physicians account for the difference in pharmacotherapeutics with every individual?

Answer 41

Drugs can be titration to provide the appropriate dose to achieve max effects and minimize side effects

Question 42

What factors influence therapeutic effects?

Answer 42

Patient factors (weight, age, pregnancy, etc), drug factors (concentration and tolerance), and drug regimen (placebo, medication error and pt noncompliance, and drug interactions)