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Pharmacology > Unit 1 Pharmacokinetic Principles > Flashcards

Unit 1 Pharmacokinetic Principles Flashcards

1
Q

Discuss the pharmacokinetic principles of Distribution.

A
  1. Factors influencing drug distribution
  2. Volume of Distribution
  3. Loading Dose
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2
Q

What are the factors that influence drug distribution?

A
  1. Blood flow to the area of action
  2. membrane permeability
  3. Plasma protein binding
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3
Q

Give an example how blood flow to the area of action can influence drug distribution.

A

Blood Brain Barrier

Prostate

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4
Q

Give an example how membrane permeability can influence drug distribution.

A

Lipophilic drugs readily cross the BBB (vs hydrophilic)

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5
Q

Give an example how plasma protein binding can influence drug distribution.

A

higher protein binding decreases unbound or “free” drug in the blood; only unbound drug can exert pharmacologic effect

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6
Q

A drug that is protein bound or unbound has the best chance of crossing the BBB?

A

Unbound

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7
Q

Bound or unbound proteins are less active?

A

Bound

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8
Q

Phenytoin is a 90% protein bound drug; 10% is free or unbound. What percentage is going to cross the BBB?

A

Unbound/free = 10%; need to give a high enough does to equal that 10%.

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9
Q

Vd

A

Volume of distribution

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10
Q

The apparent volume into which a drug distributes in the body at equilibrium.

A

Vd (volume of distribution)

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11
Q

the volume that would be required to contain the administered dose if that dose was evenly distributed in blood or plasma

A

Vd

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12
Q

Vd = __________ divided by ____________

A

amount in body (mg) / plasma drug concentration (mg/L)

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13
Q

An initial dose that is larger than subsequent doses for the purpose of achieving therapeutic drug concentrations more rapidly

A

Loading Dose

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14
Q

Loading dose = ________ x ___________

A

LD = Vd x Cp

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15
Q

Where are most drugs primarily metabolized?

A

Liver

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16
Q

What does metabolism do to drugs?

A

process makes the drug more water soluble to be eliminated.

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17
Q

List the factors that influence metabolism.

A
  1. Hepatic dysfunction (in liver)
  2. Severe CHF (decrease blood flow via liver)
  3. Advanced age (slower metabolism)
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18
Q

Metabolism slows down at what age?

A

65yrs

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19
Q

Phase I Reactions, Phase II Reactions, Prodrugs, and Active metabolites all would be classified under what pharmacokinetic principle?

A

Metabolism

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20
Q

When a drug is oxidized or reduced to more polar form?

A

Phase I Reaction

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21
Q

A Phase 1 Reaction makes a drug more water soluble or less water soluble?

A

More polar = more water soluble

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22
Q

Cytochrome P450 system is a Phase 1 Reaction or Phase 2 Reaction?

A

Phase I Reaction

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23
Q

What organ contains most of cytochrome P450?

A

liver

24
Q

List the organs where cytochrome P450 is located.

A

liver, intestines, skin, kidneys, brain, lungs

25
Q

A dug metabolized by Cytochrome P450 system is and inducer, inhibitor, or substrate?

A

Substrate

26
Q

Hydrophilic or lipophilic drugs are mostly metabolized by Cytochrome P450?

A

lipophilic

27
Q

Drug that causes more rapid metabolism of substrate drugs? Substrate, Inducer, Inhibitor, prodrug, or active metabolite?

A

Inducer

28
Q

Give an example of a drug inducer.

A

chronic EtOH

29
Q

Drug that causes slower metabolism of substrate drugs? Substrate, Inducer, Inhibitor, prodrug, or active metabolite?

A

Inhibitor

30
Q

Give an example of a drug inhibitor.

A

Cimitidine

31
Q

What is a Phase II Reaction?

A

Polar group is conjugated to the drug

32
Q

A phase II reaction will do what to polarity?

A

increase polarity

33
Q

The goal of metabolism is to make a drug more soluble or insoluble?

A

water soluble

34
Q

Describe the term prodrug.

A

inactive substance metabolized to an active substance w/in the body

35
Q

Give an example of a prodrug.

A

Prednisone metabolized & changes to prednisolone
Codeine to morphine
Fosphenytoin to phenytoin

36
Q

A prodrug has pharmacological activity? T or F?

A

False

37
Q

A metabolite that also has therapeutic activity.

A

Active metabolite

38
Q

Metabolites can be active or inactive?

A

They can function as both!

39
Q

Describe how elimination is a pharmacokinetic principle.

A

Drugs are excreted from the body after being metabolized to a more polar form; others are excreted unchanged, usually in the urine

40
Q

How are drugs eliminated?

A

Via Filtration, secretion, and reabsorption

41
Q

Term: Drugs diffuse from blood to nephron

A

Filtration

42
Q

Drugs best travel through the nephron in what form and become eliminated?

A

Small, unbound, nonionized, lipid soluble

43
Q

Explain how drug travel from high concentration to low concentration during filtration.

A

They diffuse from blood to the nephron (small, unbound, non-ionized, lipid soluble

44
Q

When do some drugs go through active transport during the elimination process? Term.

A

Secretion: Drug into the nephron

45
Q

Term:

Drugs reabsorbed into the blood stream by diffusion from the nephron tubule (small, non-ionized)

A

Reabsorption

46
Q

List factors that influence elimination.

A

Renal dysfunction; Heart Failure exacerbation, diabetes, uncontrolled HTN, decrease age

47
Q

Explain half life (t 1/2)

A

the time it takes the plasma concentration of a drug to decrease by 50% after a given dose

48
Q

Give an example of 2 anticoagulants with different half-life.

A

Heparin = 1.5hrs; Warfarin = 40 hrs

49
Q

The time from 10 hours to 5 hrs is 1 Half-life. At what point does the following half occur?

A

At 2.5 hrs.

50
Q

How is t 1/2 related to dosing frequency?

A

The longer the t 1/2, the longer the dosing interval.

51
Q

How is Vd related to t 1/2?
A. No relationship
B The smaller the Vd, the shorter the t 1/2
C. The larger the Vd, the shorter the t 1/2

A

B. The smaller the Vd, the shorter the t 1/2

52
Q

Describe Steady State

A

absorption = elimination; the drug in the body is in a state of homeostasis; generally reached in 5 half-lives.

53
Q

Heparin’s t 1/2 is 1.5 hrs. Warfarin’s t 1/2 is 40 hrs. What is there steady state?

A 
Heparin = 7.5 hours later
Warfarin = 200 hrs (8 days)
54
Q

The dose of drug that attempts to maintain a steady state plasma concentration in the therapeutic range.

A

Maintenance Dose

55
Q

Term: What drugs do to the body.

A

Pharmacodynamics

56
Q

The component of a cell or organism that interest w/ a drug and initiates the chain of biochemical events leading to the drug’s observed effects

A

Receptor

57
Q

What type of receptor alters the physiology of a cell by binding to plasma membrane or intracellular receptors

A

Agonist

Pharmacology (6 decks)

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