Lecture 01_Fall Flashcards

2
Q

Define Pharmacokinetics

A

What the body does to the drug. How does concentration in blood vary with dose, time.

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3
Q

Define Bioavailability

A

the relative amount of drug that reaches the systemic circulation

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4
Q

What is the typical bioavailability of IV drugs?

A

1

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5
Q

What is bioavailability dependent on?

A
  1. Drug absorption (ideally high)
  2. 1st pass effect (ideally low)
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6
Q

What is “First-pass Metabolism?”

A

metabolism that occurs before the drug reaches systemic circulation/target site

the liver metabolizes part of an oral or rectal medication before it can reach the site of action

(less common - Other organs - ex: lungs - first pass uptake fentanyl)

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7
Q

T or F. Drugs have to cross the membrane in order to be active in a cell and charged particles have an easier time crossing into the cell.

A

False. They do need to cross the membrane to be active, but charged particles have trouble crossing

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8
Q

What does pKa tell you?

A

the pH where ionization occurs (“50-50 point”)

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9
Q

If the pH is more acidic than the pKa, which way will the equation be driven?

A

to the RIGHT

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10
Q

T or F. A base in a basic solution will not ionize.

A

TRUE

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11
Q

What are the PROs and CONs of enteral medication?

A

Enteral = PO

PROs - easy, cheap

CONs - unreliable, need a working gut

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12
Q

What is an advantage of sublingual medication?

A

has direct absorption into systemic venous circulation, bypasses the liver, and avoids hepatic metabolism(oral transmucosal -> veins of mouth -> SVC)

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13
Q

T or F. A benefit of medications given rectally is that it bypasses the liver. *Note - this was in my lecture but not your lecture notes*

A

False…it MAY bypass the liver, but it depends on where it is absorbed.

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14
Q

Parenteral includes ___, ___, and ___ , and of these 3 routes, ___ is the best. *Note - this was in my lecture but not your lecture notes*

A

IV, IM, SQ. IV is the best

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15
Q

Name the 4 Classic Tissue Groups

A

Vessel-Rich, Muscle, Fat, and Vessel-Poor

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16
Q

What is the % Body Weight for each of the 4 tissue groups?

A

Vessel-Rich - 10%

Muscle - 50%

Fat - 20%

Vessel-Poor - 20%

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17
Q

What % of Cardiac Output goes to each of the 4 tissue groups?

A

Vessel-Rich - 75%

Muscle - 19%

Fat - 6%

Vessel-Poor - ~0%

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18
Q

T or F. A drug must bind to protein in order for it to be available for uptake by an organ?

A

False. Drugs that are bound to protein are unavailable for uptake by an organ.

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19
Q

What protein binds to acidic drugs?

A

albumin

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20
Q

What protein binds to basic drugs?

A

Alpha-1-acid glycoprotein.

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21
Q

Would a drug be more or less effective in a malnourished person?

A

more effective - lower protein levels -> higher free drug levels

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22
Q

T or F. The effects of many anesthetic drugs terminate due to redistribution.

A

TRUE

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23
Q

What is the formula for Volume of Distribution (Vd)?

A

Vd - Dose / Plasma Concentration

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24
Q

T or F. Drugs that are ionized and protein bound typically have a small Vd (Volume of Distribution).

A

True. They are usually confined to intravascular space.

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25
Q

T or F. Most drugs have a large Vd (Volume of Distribution) and don’t stay in the plasma.

A

True.

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26
Q

If the normal Total Body Water for an adult is ~42L, how can the Vd of fentanyl be 350L?

A

Fentanyl is VERY fat soluble, so it is all accumulating in the fat and the plasma concentration is very low compared to the dose given.

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27
Q

T or F. Elimination includes Bio-transformation and Excretion?

A

TRUE

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28
Q

T or F. Pancuronium is very fat soluble and has a large Vd.

A

False. Vd= 10L and TBW is 42L

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29
Q

What is biotransformation?

A

the alteration of the drug by a metabolic process

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30
Q

Where does biotransformation usually take place?

A

Liver

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31
Q

Describe Phase I of Biotransformation.

A

Phase 1: Oxidation, Reduction, Hydrolysis -> increases polarity to make the drug water soluble for excretion in urine

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32
Q

What enzyme system catalyzes most of the Phase I reactions?

A

Cytochrome P-450 (CYP)

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33
Q

T or F. Because CYP activity decreases with drug exposure, overtime, less drug is required to reach the same effect.

A

False. It increases with drug exposure - often requiring more drugs to reach the desired effect.

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34
Q

T or F. Many opioids , benzodiazepines, and local anesthetics are metabolized by CYP450 enzyme system.

A

False. CYP3A4/5 enzyme system

35
Q

What is Phase II of biotransformation?

A

Phase II: Conjugation with a polar substance -> water soluble for excretion in urine

36
Q

Hepatic Clearance is dependent on ____ and ____.

A

hepatic blood flow and hepatic extraction ratio

37
Q

Hepatic clearance of drugs with a high extraction ratio is limited by _______.

A

Hepatic blood flow (“perfusion-limited”)

38
Q

What does the term “capacity-limited” indicate about hepatic drug clearance?

What groups of patients are effected by drugs that are “capacity-limited”?

A

Drugs that have a low-extraction ratio and clearance is limited by hepatic function.

Patients with liver disease will be more effected by these drugs

39
Q

Which of the following drugs have a low extraction ratio?

A. Thiopental

B. Diazepam

C. Lorazepam

D. All of the above

A

D

40
Q

What are the 3 routes of excretion?

A

Kidneys (urine)

Bile (stool)

Lungs (mostly volatile agents, some clearance of fentanyl)

41
Q

T or F. Protein bound drugs are filtered into the kidneys, are ionized in urine and are unable to be reabsorbed.

A

False. All is true except that it is non-protein bound drugs that are filtered into the kidneys

42
Q

Define clearance.

A

Removal of drug from the plasma - specifically, the volume of plasma cleared of drug (by metabolism or excretion) per unit of time

43
Q

T or F. Drugs must be metabolized to an inactive metabolite in order to be excreted by the kidneys.

A

False.

44
Q

Define half-life.

A

time required for serum concentration to drop by one-half

45
Q

What are the two compartments in the 2-Compartment Model?

A

Central Compartment (Plasma + VRG) and the Peripheral Compartment

46
Q

T or F. The alpha phase described in the 2-Compartment Model refers to the Elimination Phase which is characterized by slower decline in drug concentration in the plasma.

A

False. The alpha phase is the Distribution Phase in which a quick decline occurs. The beta phase is the Elimination Phase which is characterized by slower decline in drug plasma concentration.

47
Q

Does the following describe Zero-Order or First -Order Kinetics?

a fixed percentage of the drug is metabolized per unit of time for any given plasma concentration.

A

First order kinetics

48
Q

Does the following describe Zero-Order or First -Order Kinetics?

a constant amount of drug is metabolized per unit of time, independent of plasma concentration.

A

Zero order kinetics

49
Q

Alcohol is an example of ______-order kinetics

A

Zero-order kinetics

50
Q

Most drugs are metabolized according to ____-order kinetics.

A

First-order kinetics

51
Q

On a Concentration Vs. Time graph, elimination by ____-order kinetics is characterized by a straight line.

A

zero-order kinetics

(there is zero change in the slope!)

52
Q

Define Pharmacodynamics

A

What the drug does to the body

53
Q

Define Efficacy

A

the maximum effect a drug can cause

54
Q

Define Potency

A

the amount of effect a drug causes for a given dose

55
Q

What is ED50?

A

The drug dose required to produce a specific effect in 50% of the population

56
Q

What is LD50?

A

The drug dose required to cause death (or toxicity) in 50% of the population

57
Q

T or F. An ideal drug has a very narrow therapeutic index.

A

False.

58
Q

What is the formula for Therapeutic Index?

A

LD50/ED50

59
Q

_____ is a diminished response to a drug due to chronic exposure.

A

Tolerance

60
Q

______ is an acute drug tolerance after only a few doses.

A

Tachyphylaxis

61
Q

______ antagonists bind reversibly to the same binding site as agonists

A

Competitive Antagonists

62
Q

_____ antagonists bind to a separate binding site on the same receptor as the agonist

A

Non-competitive Antagonists

63
Q

____ antagonists could be overcome by increasing the dose of an agonist.

A

Competitive Antagonists

64
Q

T or F. Partial Agonists have higher efficacy than full agonists.

A

False. They produce a lower maximal response

65
Q

Lipophilic drugs rapidly equilibrate into ____.

A

CNS tissue

66
Q

single doses of lipophilic drugs have a ____ CNS duration of action.

A

short

67
Q

Multiple doses of lipophilic drugs leads to increasing _____ concentrations and ____ duration of action.

A

peripheral tissue, longer

68
Q

After multiple doses of a lipophilic drug, decrease in plasma concentration becomes dependent on _____.

A

drug elimination from the body

69
Q

T or F. Facilitated diffusion of drugs through the lipid bilayer requires energy since carrier proteins are needed.

A

False. Carrier proteins are needed but requires no energy

70
Q

Passive transport is typically limited by ____ not ___.

A

blood flow, not lipid solubility

71
Q

T or F. Unlike lipophilic drugs, hydrophilic drugs need active transport to deal with concentration gradients.

A

False. They both do.

72
Q

What age group has diminished Phase I and Phase II activities?

A

neonates - 1 yr

73
Q

What is hepatic drug clearance?

A

the fraction of drug removed when blood passes through liver

74
Q

GFR = ___% RBF

A

20%

75
Q

Why is passive transport insufficient for renal drug clearance?

A

due to protein binding

76
Q

To determine what loading dose to give, you must multiply ____ and ____.

A

Loading dose = Vd x target concentration

77
Q

In general, do lipophilic or hydrophilic drugs have a larger Vd?

A

lipophilic

78
Q

Why does Thiopental have a prolonged 1/2-life in the elderly?

A

Vd is increased

79
Q

Our drugs often have a two-tailed therapeutic index. What does this mean?

A

There are both low (awareness) and high (overdose) “toxicities” to avoid.

80
Q

What is redundancy of drug receptors?

A

excess of receptors. Max drug effect typically occurs at far below max receptor binding

81
Q

NMJ only needs __% of receptors to be bound by Ach for clinical strength, which is why you need >___% blockage to get clinical weakness.

A

25%, 75%

82
Q

T or F. You should ALWAYS be very familiar with the graphs on the notes because there is a good chance you will have to draw and label it on your quizzes or tests.

A

TRUE :)