Brainscape's Knowledge GenomeTM

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


See full index

Anesthesia > Pharmacokinetics and Pharmacodynamics > Flashcards

Pharmacokinetics and Pharmacodynamics Flashcards

1
Q

Define liberation

A

Liberation is the first step of absorption.

Liberation is the separation of a drug from its vehicle.

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

Why does atropine cross the BBB while glycopyrolate does not?

A

Atropine is neutral

Glycopyrolate is + charged and thus can’t cross the BBB

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

Compare and contrast intrathecal morphine vs. fentanyl

A

Morphine = hydrophilic –> persists in circulation

Fentanyl = hydrophobic –> binds quickly to surrounding fat and protein affecting nearby nerve roots

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

Compare and contrast the alpha and beta phases of elimination

A

Alpha - distribution phase of a drug from central circulation to the periphery right after a bolus

Beta - elimination, metabolism + excretion

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

Define volume of distribution of a drug

A

Volume = dose (mg) /concentration (ml)

Volume of distribution exceeds total body volume in fat soluble or highly protein bound drugs

Children have larger volumes d/t larger intravascular and extracellular volumes

Dec protein in elderly, anemia and hypoalbuminemia = lower volume

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

What is the Law of Mass Action?

And why rocuronium has a quicker onset than equipotent vecuronium?

A

Larger dose = faster onset

= use a greater quantity of a less potent drug

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

How many half lives of an oral drug to reach steady-state?

A

4-5

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

Explain 1st order elimination

A

Rate of elimination is proportional to the concentration of the drug. A constant proportion of the drug is eliminated

Exponential decay process:
8-4-2-1

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

How does an antagonist effect the dose response curve?

A

Shift curve to the right

• Antagonist – block other drugs but cause no activity
 Competitive – physically displace agonist w/o blocking
 Non-competitive – irreversibly bind to receptor

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

How does a noncompetitive antagonist effect the dose response curve?

A

Shift to right and reduce max efficacy

Non-competitive – irreversibly bind to receptor

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

How does a partial agonist effect the dose response curve?

A

Sub maximal response

• Partial agonist – partially activate even at [high]

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

What is therapeutic index?

A

TD50 / ED50

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

GABA receptor belong to what receptor type?

A

Ligand-gated ion channel

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

Drug potency is determined by what factors?

A

Affinity to the receptor
And receptor response to drug binding

Higher potency = lower ED50

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

What type of agonist/antagonist decreases receptor response to a level below baseline response observed?

A

Inverse agonist

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

What type of ligand effect does buprenorphine exhibit?

A

Partial mu agonist

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

What type of drug will decrease efficacy of an agonist w/o affecting its potency?

A

Noncompetitive antagonist

18
Q

Explain 0 order elimination

A

Cleared at a constant rate, irrespective of the plasma concentration.

Ex: alcohol

19
Q

Explain context-sensitive half-life

A

Fat soluble drugs accumulate over time –> Half-life increases over time.

A continuous infusion has to be dialed back in long cases to prevent overdoses.

However other drugs like remifentanil don’t.

20
Q

What are the two major plasma proteins that affect drug protein binding?

A
  1. Albumin

2. alpha-1 acid glycoprotein (acute phase reactant)

21
Q

Which plasma protein binds acidic drugs and basic drugs most readily?

A

Acidic = Albumin

Basic = (alpha-1)(narcotics, amines)

22
Q

Would a weak acid or a weak base more readily cross the cell membrane?

A

Weak acid

  • it donates H+ becoming non-ionized and can easily cross
23
Q

What is the pKa of a drug?

A

The pH at which half the drug is in its ionized form and half in its non-ionized form.

  • The lower the pH relative to the pKa, the greater the fraction of drug in the ionized form.
  • Local anesthetics are weak bases, infected tissue is acidic –> LA becoming ionized and unable to penetrate the membrane to exert their action
24
Q

Compare the solubility of high blood: gas coefficient gases to low blood: gas coefficient gases

A

High blood: gas = more soluble = passes easily from air to blood

25
Q

What factors make a molecule transfer across cell membrane more quickly?

A

low degree of ionization
low molecular weight
high lipid solubility
high concentration gradient

26
Q

What causes the initial decline in drug concentration of a lipophilic drug and what is it dependent on?

A

Redistribution
Dependent on cardiac output - high CO tissues = faster equilibrium

CO is based on LEAN body mass

27
Q

What drugs are metabolized by CYP3A4?

A

Tylenol, dexamethasone, lidocaine, midazolam, methadone, fentanyl, alfentanil, sufentanil, little bit of propofol

28
Q

Name inhibitors of CYP3A4

A 
grapefruit juice
anti-fungals
protease inhibitors
“mycins”
SSRIs
29
Q

Name inducers of CYP3A4

A 
Rifampin
rifabutin
tamoxifen
glucocorticoids
carbamazepine
barbiturates
St. John’s Wort
30
Q

What drugs are metabolized by CYP2B6?

A

Propofol, codeine, oxycodone, hydrocodone

31
Q

What class of drugs inhibits CYP2B6?

A

SSRIs

32
Q

What drugs are metabolized by plasma esterases?

A

Remifentanil, succinylcholine, esmolol

Succinylcholine – pseudocholinsterase or butylcholinesterase can be cleared slowly with genetic defect

33
Q

What drugs are extensively really cleared?

A

Steroidal muscle relaxants

85% pancuroniu
20-30% vecuronium
10-20% rocuronium

34
Q

What is the formula for calculating CrCl?

A

Cockroft-Gault
(140-age) x weight (kg) / 72 x serum Cr (mg%)

Women are this x 85%

Old people with normal Cr STILL have lower clearance

35
Q

What drugs utilize the Ligand-gated type receptor?

A 
Propofol
midazolam
thiopental
ketamine
muscle relaxants
36
Q

Define tolerance

A

reduction in the pharmacologic response to a drug following exposure to the drug or a similar drug

Inc amounts to produce same effect

37
Q

What are the types of drug tolerance?

A
  1. Innate - genetic predisposition that renders one less sensitive to a drug = Opioid receptor gene polymorphisms
  2. Acquired - increased metabolism as a result of liver enzyme induction (barbiturate and ketamine), receptor down-regulation (opioids) or desensitization (a reduction in the efficacy of a receptor-bound drug to produce its effect).
38
Q

What are the mechanisms for tolerance?

A
  1. receptor down-regulation
  2. desensitization
  3. enzyme induction
39
Q

What is tissue tolerance?

A

increasing quantities of opioids are required to produce analgesia, euphoria, and respiratory depression, but tolerance to miosis and constipation does not develop

40
Q

What is tachyphylaxis?

A

Acute tolerance

41
Q

What is one mechanism for the development of tachyphylaxis?

A

depletion of neurotransmitter stores

42
Q

Name 5 drugs associated with tolerance and tachyphylaxis besides opioids.

A

ephedrine (depletion of norepinephrine stores)

nitrates (depletion of sulfhydryl groups)

succinylcholine (prolonged ion channel opening)

desmopressin (depletion of both Factor VIII and vWF)

Epidural lidocaine

Anesthesia (25 decks)

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