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GNURS625 Pharmacology for Anesthesia 1 > Pharmacokinetics > Flashcards

Flashcards in Pharmacokinetics Deck (71)
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1
Q

Pharmacokinetics include

A

Absorption
Distribution
Metabolism
Excretion

2
Q

Bioavailability (F) is

A

% of medication that reaches systemic circulation

3
Q

Oral Administration: Considerations in GI Tract

A
  • Gastric pH and contents
  • Surface area
  • Blood flow
  • GI motility
  • Complete GI tract
  • Flora
4
Q

Sublingual/Buccal route drains to ________, Very rapid.

• Must be HIGHLY _______ and _________

A

vena cava

lipid soluble and potent

5
Q

90% of oral medication is metabolized and destroyed by the

A

liver

6
Q

Topical eye gtts may become systemic via the

A

nasolacrimal canal

7
Q

Topical administration includes

A

Skin, eye, inhalation

8
Q

Inhalation agents avoid

A

first pass metabolism

9
Q

Simple diffusions rates are limited by:

A

amount of capillaries, solubility, molecular size and composition

10
Q

Volume of Distribution is the

A

Size of compartment necessary to account for the total amount of drug in the body if it were present throughout the body at the same concentration found in the plasma
• Average adult plasma Vd= 3 Liters
• Total body water = 0.65 L/kg

11
Q

Loading Dose =

A

Vd x Cd

12
Q

Two Compartment Model:

A

• Re-distribution before elimination
• Slow rate of administration for secondary re-
distribution
• Target organ may be in the initial or secondary “compartment”

13
Q

Due to Protein Binding, the Unbound/free drug =

A

active

14
Q

Tissue Binding examples:

A

Fat: Reservoir for lipid soluble drugs
• Bone: Tetracyclines
• Heart muscle: Digoxin

15
Q

In order to enter an organ, a drug must ___________ that separate the organ from the site of drug administration.

A

permeate all membranes

16
Q

Fetal plasma is more acidic, therefore ion trapping of _______ drugs occurs

A

basic

• P-glycoproteins limit transport

17
Q

P-glycoproteins are

A

• Family of transporter proteins
• Found all over, including the blood brain barrier
• Kidney, colon, jejunum, liver, pancreas
• Important for medication interactions and
drug resistance
• Requires ATP

18
Q

Passive diffusion, carrier? energy?
Facilitated diffusion, carrier? energy?
Aqueous channels. carrier? energy?
Active Transport. carrier? energy?

A

Passive Diffusion No, No
Facilitated Diffusion No, Yes
Aqueous Channels No, No
Active Transport Yes, Yes

19
Q

Metabolism is the

A
  • Breakdown for ease of elimination
  • May become active (prodrug) or inactive
  • Metabolites may be more toxic than parent compound
20
Q

Phase I Metabolism is

A
  • Induce or expose a functional group on the parent compound
  • Generally lose activity, rare instances of preserved.
  • Then often hydrolyzed or ester linked for rapid elimination thru the kidneys
21
Q

Phase II Metabolism

A

• Conjugation reactions
• Links parent compound OR phase I
metabolite with a functional group via
covalent linkage
• Functional groups: glucouronic acid, sulfate, glutatione, amino acid, acetate
• Example: Morphine: 6-glucouronide metabolite
• Becomes MORE active than parent compound

22
Q

Most reactions are ______ driven

A

enzyme

23
Q

Cytochrome P450 is

A
  • Terminal oxidase in a multicomponent electron transfer chain
  • Phase I type reactions
24
Q

Inhibition:

A
  • Inhibition: Will keep the enzyme from working properly

* Ability to increase amount of parent compound

25
Q

Induction:

A
  • Induction: Will enhance the capability of the enzyme

* Ability to quickly metabolize the parent compound

26
Q

Factors Affecting Metabolism

A
  • Genetics
  • Environmental, diet
  • Disease Factors
  • Age and Sex
27
Q

Easier to eliminate _________ compounds than ____________ compounds

A

Easier to eliminate polar/hydrophillic compounds than lipophillic compounds

28
Q

Renal elimination includes 3 processes:

A
  • Glomerular Filtration
  • Active tubular secretion
  • Passive tubular reabsorption





29
Q

Besides renal elimination, other routes of elimination include:

A
  • Biliary and Fecal
  • Sweat, saliva and Tears
  • Lungs
30
Q

In first order kinetics, the length of the half life is

A

constant, curved downward slope

31
Q

In zero order kinetics,

A

half life decreases with decreasing concentration

straight down slope (45 degree)

32
Q

Elimination Rate (k): is the

A

fraction or % of the total amount of drug in the body removed per unit of time

33
Q

Half Life and Elimination Rate are used to estimate the

A

estimate the time to steady state
• Estimate the time to eliminate the medication
from the body
• Predict non-steady state plasma levels
• Predict steady state from a non-steady state level
• Determine dosing intervals

34
Q

pharmacokinetics is

A

what the body does to the drug (ADME)

35
Q

pharmacodynamics is

A

what the drug does to the body

36
Q

Steady state is

A

Amount of drug administered over time = amount of drug eliminated during the same time period
- rate in = rate out

37
Q

A steady state is acheived after

A

4-5 half lives

38
Q

Does a loading dose shorten the time to ready steady state?

A

NO

39
Q

Would you reach steady state faster if the dose was given at one half of the medication’s half life?

A

NO

40
Q

How to interpret drug levels:

A
  • NEVER treat an isolated number n check dosing history

- Always treat the patient not the number

41
Q

A trough is drawn to check

A

efficacy

42
Q

A peak is drawn to check

A

toxicity

43
Q

Drugs exert their primary action at the

A

cellular level

44
Q

Most drugs bind to ____________ where they initiate biochemical reactions that alter the cell’s physiology

A

cellular receptors

45
Q

There is a _____ number of receptors on a given cell.

A

finite

46
Q

The strength of binding between a drug and its receptor.

A

Affinity

47
Q

The measure of a drug’s affinity for a given receptor. The concentration of drug required in solution to achieve 50% occupancy of its receptors.

A

Dissociation Constant (Kp)

48
Q

Drugs which alter the physiology of a cell by binding to plasma membrane or intracellular receptors.

A

Agonist

49
Q

an agonist which causes maximal effects even though it may only occupy a small fraction of receptors on a cell.

A

Strong Agonist

50
Q

an agonist which must be bound to many more receptors than a strong agonist to produce the same effect.

A

Weak Agonist

51
Q

inhibit or block actions caused by agonists.

A

Antagonist

52
Q

competes with agonist for

receptors.

A

Competitive antagonist

53
Q

binds to a site other than the agonist-binding domain. Induces a conformational change in the receptor such that the agonist no longer “recognizes” the agonist-binding domain.

A

Noncompetitive antagonist

54
Q

agents compete with agonists for the agonist-binding receptor .

A

Irreversible antagonism

55
Q

The degree to which a drug is able to cause maximal effects.

A

Efficacy

56
Q

the amount of drug required to produce 50% of the maximal response that the drug is capable of causing.

A

Potency

57
Q

is frequently used to compare drugs within the same chemical class. Drugs within the same chemical class will usually have similar maximal efficacy if a high enough dose is given.

A

Potency

58
Q

is used to compare drugs with different mechanisms. For example, toradol (NSAID) has equal efficacy to morphine (narcotic) in controlling post-op pain.

A

Efficacy

59
Q

Before new drugs are approved for marketing, their _______and _________ must be tested in animal and human population studies.

A

efficacy and safety

60
Q

EC50

A

(Effective Concentration 50%) The concentration of drug which induces a specified clinical effect in 50% of the subjects to which the drug is administered.

61
Q

LD50

A

(Lethal Dose 50%) the concentration of drug which induces death in 50% of the subjects to which the drug is administered.

62
Q

Therapeutic Index

A

a measure of the safety of a drug. Calculated by dividing the LD50 by the ED50.

63
Q

Margin of Safety

A

the margin between therapeutic and lethal doses of a drug.

64
Q

Drug interaction: addition

A

the response elicited by combined drugs is EQUAL TO the combined responses of the individual drugs. 1+1=2

65
Q

Drug interaction: synergism

A

the response elicited by combined drugs is GREATER THAN the combined responses of the individual drugs. 1+1=3

66
Q

Drug interaction: potentiation

A

A drug which has no effect enhances the effect of a second drug. 0+1=2

67
Q

Drug interaction: antagonism

A

Drug inhibits the effect of another drug. Usually, the antagonist has no inherent activity. 1+1=0

68
Q

Tolerance represents a

A

decreased response to a drug, dose of a drug must be increased to achieve the same effect.

69
Q

Dependence occurs when a patient needs a drug to

A

“function normally”

  • Clinically this is noted when cessation of a drug produces withdrawal symptoms.
  • Dependence may be both physical and/or psychological.
70
Q

Withdrawal occurs when a drug is

A

not administered to a person who has become dependent on it.

§ Symptoms of withdrawal are often opposite the effects achieved by the drug.

71
Q

CRRT provides an average of what creatinine clearance

A

30 mL/min