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Apex > Pharmacokinetics > Flashcards

Pharmacokinetics Flashcards

1
Q

How do you calculate the required loading dose of a medication?

A
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2
Q

What is the bioavailability of an IV medication?

A

It’s always equal to 1, because it’s being injected directly into the bloodstream. There is no first pass effect

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3
Q

Steady state is achieved after:

A

About five half lives

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4
Q

What is steady state?

A

When the rate of administration is equal to the rate of elimination

When the amount of drug entering the blood stream is equal to the amount of drug being excreted

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5
Q

What is the elimination half life?

A

The time required for the amount of drug in the plasma to decrease by 50%

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6
Q

After three half lives, what percentage of a drug is removed?

A
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7
Q

Which is more likely to undergo renal elimination: an ionized or non-ionized drug?

A

An ionized drug, because it is hydrophilic

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8
Q

Which is more likely to undergo hepatic metabolism: an ionized drug or a non-ionized drug?

A

A non-ionize drug, because it is lipophilic

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9
Q

Fetal pH is typically _________ than maternal pH

A

lower

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10
Q

Ion trapping is of highest concern in a ______ mother and ______ fetus

A

alkalotic mother and acidotic fetus

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11
Q

What local anesthetic is the most likely to undergo fetal ion trapping?

A

Lidocaine

Chloroprocaine is the least

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12
Q

Albumin typically binds acidic or basic drugs?

A

Acidic

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13
Q

Alpha-1 Glycoprotein typically binds acidic or basic drugs?

A

Basic

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14
Q

Plasma concentrations of albumin are decreased by:

A

Liver Failure
Renal Disease
Old Age
Malnutrition
Pregnancy

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15
Q

Plasma concentrations of Alpha 1 Glycoprotein is increased by:

A

Surgical stress
MI
Chronic Pain
Rheumatoid Arthritis
Advanced Age

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16
Q

Plasma concentrations of alpha 1 glycoprotein are decreased by:

A

Neonates
Pregnancy

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16
Q

Zero order kinetics occur when:

A

there is more drug than enzyme, so the enzyme metabolized at a set rate

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17
Q

What are some drugs that follow zero order kinetics?

A

Alcohol
Aspirin
Phenytoin
Warfarin
Theophylline
Heparin

18
Q

What’s the difference between zero order and first order kinetics?

A

Zero order: constant AMOUNT per time unit

First order: constant FRACTION per time unit

19
Q

Drug metabolism is divided into three phases:

A
  1. Modification
  2. Conjugation
  3. Excretion
20
Q

What is biotransformation?

A

The process of altering a molecule’s chemical structure

It’s just another word metabolism

21
Q

What is the purpose of metabolism?

A

To change a lipid-soluble, pharmacologically active compound INTO
a water-soluble, inactive compound

22
Q

What are some common examples of phase 1 reactions?

A

Oxidation
Reduction
Hyrolysis

23
Q

What happens in phase 2 reactions?

A

conjugation of a highly polar, water-soluble substrate to the molecule, inactivating the drug and making it easier to eliminate

24
Q

What happens in phase 3 reactions?

A

ATP-dependent transport across a cell membrane

25
Q

What happens when lipophilic drugs that do not undergo biotransformation reach the kidney?

A
26
Q

Most phase 1 biotransformations are carried out by:

A

the liver P450 system

27
Q

For drugs with a low hepatic extraction ratio, clearance is dependent on:

A

the ability of the liver to extract the drug
(extraction dependent)

The amount of blood flow through the liver has very little effect

28
Q

For drugs with a high hepatic extraction ratio, clearance is dependent on:

A

liver blood flow (perfusion dependent)

Hepatic blood flow exceeds enzymatic activity, so changes in perfusion have very little effect

29
Q

What is the hepatic extraction ratio?

A

the ratio of drug delivered vs. drug extracted

30
Q

Co-adminstration of which drug decreases the efficacy of codeine?

A

Fluoxetine

31
Q

Which P450 enzyme is responsible for 50% of drug metabolism?

A

CYP 3A4

32
Q

The P450 system is the most important mechanism of drug _________

A

biotransformation (metabolism)

33
Q

Where are P450 enzymes located?

A

the smooth endoplasmic reticulum of hepatocytes

34
Q

Which drugs are CYP inducers?

A
35
Q

Which drugs are CYP inhibitors?

A
36
Q

Which drugs are CYP substrates?

A
37
Q

Acidic urine favors:

A
  • Reabsorption of acidic drugs
  • Excretion of basic drugs
38
Q

Basic urine favors:

A
  • Reabsorption of basic drugs
  • Excretion of acidic drugs
39
Q

Which drugs are metabolized by pseudocholinesterase?

A
40
Q

Which drugs are metabolized by nonspecific esterases?

A
41
Q

Pharmacokinetics explains:

A

what the body does to the drug

42
Q

Pharmacodynamics explains:

A

what the drug does to the body

Apex (46 decks)

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