Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

SRNA4TopicsAnesthesia > VALLEY PHARK/PHARMD > Flashcards

VALLEY PHARK/PHARMD Flashcards

1
Q

What is a dose-response curve?

A

A dose-response curve depicts the relationship between the dose of a drug administered (x- axis) and the resulting pharmacologic effect (y- axis).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

x-axis of the dose-response curve?

A

Dose of drug administered.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

y-axis of the dose-response curve?

A

Pharmacologic effect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Dose-response curves are characterized by differences in

A

(I) potency, (2) slope,

(3) efficacy, and (4) individual variability.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe how potency of a drug is depicted by the dose-response curve.

A

The potency of a drug is depicted by its location along the dose axis (usually the x- axis) of the dose-response curve.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Increased affinity of a drug for its receptor shifts the curve to the

A

left

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Decreased affinity of a drug for its receptor shifts the

curve to the

A

right.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Drug potency and receptor affinity are______ related-

A

directly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

MNEMONIC left shift.

A

Left-shift = Less drug required:;: More potent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

A more potent drug has a _______for its receptor

A

greater affinity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What does the slope of a dose-response curve reveal about the drug?

A

The slope of the dose-response curve indicates the number of receptors that must be occupied (bound) before a drug effect occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

A steep dose-response curve slope means that

A

a majority of the receptors must be bound before a relevant effect occurs.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Drugs classes with steep slopes

A

Neuromuscular blocking drugs and inhaled anesthetics dose-response curves have steep slopes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Define drug efficacy. Which feature of a dose-response curve indicates the efficacy of a drug?

A

Efficacy is a measure of the intrinsic ability of a drug to produce a given physiologic or clinical effect.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

The maximal effect of a drug reflects its

A

intrinsic activity, or efficacy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

A drug’s efficacy is depicted by

A

the plateau of the dose-response curve.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

A higher plateau correlates with

A

with a greater efficacy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Describe how the presence of a competitive antagonist would alter a dose-response curve of a drug.

A

The presence of a competitive antagonist (inhibitor) would shift the dose-response curve to the right, with no change in the efficacy (plateau) or slope.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

The rightward shift caused by competitive antagonist (inhibitor) is caused by

A

competition for the same number of receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Describe how the presence of a noncompetitive

antagonist would alter the dose-response curve of a drug.

A

The presence of a noncompetitive antagonist (inhibitor) would shift the curve rightward and downward, with a decrease in the slope of the curve.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Changes with noncompetitive antagonist in the curve is because?

A

because a maximal effect cannot be achieved in the presence of a noncompetitive block.

22
Q

A noncompetitive block cannot be

A

reversed by excess agonist.

23
Q

What is LD50/ED50? The therapeutic
index is defined as the dose that is lethal in 50% of subjects (LD50) divided
by the dose required to produce the desired effect in SO% of patients
(EDso). Mathematically, Tl = LDso/EDso. The larger the therapeutic index
(Tl) of a drug, the greater margin of safety. Note: EDso is the median effective
dose and LD50 is the median lethal dose.

A

This ratio is the therapeutic index (TI), or margin of safety.

24
Q

The therapeutic index is defined

A

as the dose that is lethal in 50% of subjects (LD50) divided

by the dose required to produce the desired effect in SO% of patients (ED50).

25
Q

Tl = LD50/ED50. The larger the therapeutic index (Tl) of a drug,

A

the greater margin of safety.

26
Q

Note: ED50 is the median effective

A

dose and LD50 is the median lethal dose.

27
Q

Define tachyphylaxis

A

Tachyphylaxis is the fairly rapid (acute) development of resistance to the effects of a drug.

28
Q

A typical adult can metabolize about 10g of ethanol per hour. How long would it take to metabolize three ounces of 80 proof vodka martini (shaken, not stirred … of course). Assume the martini was consumed at once. One ounce of 80 proof alcohol contains approximately 10 g of ethanol

A

Recognize this is a zero-order kinetics problem. With zero-order kinetics, a constant amount of substance is eliminated per unit time, as you know, resulting in a linear trend with a negative slope when the data is graphed.
This is not a half-life problem; therefore, the half-life table is not necessary.
3oz (10g/1oz ethanol) = 30g ethanol
30g ethanol (1hr to eliminate/10g ethanol) = 3 hours

29
Q

What is the elimination half-time (T112) of a drug? What two factors determine elimination half-time (T 1/2)

A

Elimination half-time is the time taken for the plasma concentration to fall by one-half.

30
Q

Eimination half-time is related?

A

directly related to volume of distribution (Vd) and inversely related to clearance (Cl).

31
Q

What is the “context-sensitive half-time” of a drug and how does it differ from elimination half-time?

A

The context-sensitive half-time describes the time necessary for the plasma drug concentration to decrease by 5O% (or any other percent) after discontinuing
a continuous infusion of a specific duration.

32
Q

Context In “context sensitive half time” is

A

“Context” refers to the infusion duration

33
Q

Context-sensitive half-time, in contrast to elimination

half-time, considers the

A

combined effects of distribution and metabolism as

well as duration of continuous IV administration on drug pharmacokinetics.

34
Q

What is a substantial limitation to the context-sensitive half-time concept?

A

The context-sensitive half-time describes only the time to a 50% decrease in the central compartment concentration, which may not correlate with the time to achieve recovery

35
Q

A substance with what clearance (large or small?) and what volume of distribution (large or small?) will have the
longest half-time of elimination?

A

Half-time of elimination is greater if: (a) volume of distribution is large and/or (b) clearance is small.

36
Q

Clearance formula

A

Vd/T 1/2

37
Q

A drug is eliminated by first order kinetics. Four grams of the drug are admin istered. Five hours later, two grams had
been metabolized. After I0 more hours, how much more is metabolized?

A

1.5 g. For first order kinetics, one-half of the drug is gone in one half-life. In this case, the half-life is five hours because the amount of drug decreased from 4 g to 2 g in five hours. In the next five hours, 1 g is lost and five hours later another 0.5 g is lost.

38
Q

If a drug is excreted by first order kinetics, how long will it take for the plasma concentration to fall to 50 mg if
its half-life is 20 hours and 200 mg was administered?

A

40 hours. For drugs that are excreted by first order kinetics, the plasma concentration decreases by one-half during each half-life. The concentration falls from 200 mg to 1OO mg in the first 20 hours (one half-time) and
from 100 mg to 50 mg in the next 20 hours

39
Q

If 60 mg of a drug is given and 15 mg remain after 12 hours, how much drug is eliminated in the next 12 hours?

A

11.25 mg. The half-life is 6 hours (the amount of drug decreases from 60 mg to 30 mg in 6 hours and from 30 mg to 15 mg in the next 6 hours). Half of the remaining 15 mg, or 7.5 mg, will be excreted in the next 6 hours and,
one·half of7.5 mg, or 3.75 mg, in the next 6 hours. Thus, 7.5 mg+ 3.75 mg = 11.25 mg will be excreted in the next 12 hrs.

40
Q

Diffusion of a drug across a membrane is proportional to the concentration gradient. Diffusion is also dependent on
what 3 other factors?

A

(1) Solubility of drug in lipid (the greater the lipid solubility, the greater the rate of diffusion), (2) thickness of membrane and (3) molecular weight

41
Q

Diffusion accross a membrane is

A

Proportional to the concentration gradient.

42
Q

Molecular weight and diffusion

A

the greater the molecular weight, the lower the rate of diffusion

43
Q

Thickness of the membrane and diffusion

A

thickness of membrane (the greater the membrane thickness, the lower the rate of diffusion)

44
Q

Solubility and diffusion

A

The greater the lipid solubility, the greater the rate of diffusion

45
Q

The degree of protein binding of a drug in the blood is dependent upon what primary factor?

A

The total amount of protein in blood. It is important for the anesthetist to recognize that the amount of drug bound to protein will change when plasma protein levels change

46
Q

What is the most important plasma protein for binding of drugs?

A

Albumin.

47
Q

Rank the following routes of drug administration,
from greatest to least, with regards to peak plasma concentration: subcutaneous, intravenous (IV), caudal
epidural, and intratracheal

A

Peak plasma concentration, from greatest to least, based upon route of administration is:
intravenous >= intratracheal > caudal epidural > subcutaneous.

48
Q

Identify the most important determinant of the build-up of an intravenous anesthetic in a given tissue.

A

The blood flow to the tissue

49
Q

Besides blood flow , 2 other factors that determine the amount of IV anesthetic going into and out of a tissue compartment

A

Lipid solubility

Degree of ionization in plasma.

50
Q

Drugs that are absorbed from the gastrointestinal

tract must first pass through which organ before reaching the general circulation?

A

The drugs are delivered to the liver via the portal circulation. Drugs that are absorbed from the GI tract may be metabolized to some extent in the liver-this is the.first-pass effect

51
Q

Drugs that are absorbed from the gastrointestinal
tract may be metabolized to some extent by the liver before reaching the general circulation. What is this
effect called?

A

The first-pass effect.

52
Q

During resuscitation, if venous access has not or cannot be established, what route of administration can result in
high peak plasma drug levels?

A

Intra-tracheal administration of resuscitative drugs through an endotracheal tube results in high peak plasma drug levels, nearly identical to those achieved via the intravenous route.

SRNA4TopicsAnesthesia (47 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions