Module 7- Pharmacokinetic, Weak Acid & Base, LA

Question 1

Constant amount of drug is eliminated per unit time is

Examples

Answer 1

Zero order kinetics

Alcohol, phenytoin, aspirin

Question 2

Contend fraction of a drug is eliminated per unit time

Answer 2

First order kinetics

Question 3

In two compartment model of first order kinetics the distribution phase is aka

Answer 3

Alpha phase (steel decline in line after administration)

Question 4

In two compartment model of first order kinetics the elimination phase is aka

Answer 4

Beta phase

Question 5

Phase I reaction involve

Answer 5

Chemical biotransformation of a molecule

Oxidation, reduction, methylation, hydrolysis

Cytochrome P450 is responsible for most of these reactions

Question 6

Phase II reactions involve

Answer 6

Conjugation of a drug or its metabolic. Make drugs water soluble for excretion by kidneys or biliary system

Question 7

How potency of a drug is depicted by dose response curve

Answer 7

Left shift = less drug required = more potent

Question 8

What does the slope of the dose response curve reveal about the drug

Answer 8

Steep curve means majority of receptors must be bound before a relevant effect occurs.

Question 9

Drugs efficacy is depicted by what part of the dose response curve

Answer 9

Plateau. Higher plateau correlates with greater efficacy

Question 10

Formula for therapeutic index

Answer 10

LD50/ED50

Larger TI of a drug the greater the margin of safety

Question 11

Describe first pass effect

Answer 11

Drugs absorbed through GI tract delivered to liver via portal circulation and metabolized somewhat by liver before being delivered to systemic circulation

Question 12

Allergy to PCN is likely to have cross sensitivity to what other group of antibiotics

Answer 12

Cephalosporins (cefazolin, cefoxitin, cefotaxime)

Question 13

There is a cross sensitivity among which group of LA. Why

Answer 13

Ester local anesthetics due to a common metabolite para-aminobenzoic acid

Question 14

Xanthines (theophylline and aminophylline) inhibit the breakdown of cAMP and

Answer 14

Inhibit interaction of adenosine with purinergic receptor leading to increased NE release from nerve fibers

Question 15

Sodium drug, calcium drug, magnesium drug = weak acid or weak base

Answer 15

Weak acid

Question 16

Drug sulfate, drug chloride = weak acid or base

Answer 16

Base

Question 17

Local anesthetics are weak (acid/base) and become (more/less) ionized as pH increases

Answer 17

Weak bases

Less

Question 18

What part of local anesthetics imparts its lipophilic properties

Answer 18

Aromatic ring

Question 19

Ester Metabolism

Answer 19

Metabolized by plasma cholinesterase (except cocaine)

Question 20

Amide metabolism

Answer 20

Metabolized by hepatic cytochrome P450 enzymes

Question 21

The lower the pKa of LA the (more/less) the proportion of LA in non-ionized form at pH7.4 = (faster/slower) onset of block

Answer 21

More non-ionized = faster onset

Question 22

The more lipid soluble the LA, the (more/less) potent

Answer 22

More

Question 23

Most important factor in determining duration of LA

Answer 23

Protein binding

Question 24

Height of sensory vs motor vs sympathetic block

Answer 24

Sympathetic block is 2-6 levels higher than sensory block

Motor block is 2 levels lower than sensory block

Question 25

Max dosage cocaine and tetracaine

Answer 25

3 mg/kg

Question 26

Max dosage procaine and chlorpromazine

Answer 26

12 mg/kg

Question 27

Max dosage bupivacaine and ropivacaine

Answer 27

3 mg/kg

Question 28

Max dosage lidocaine and mepivacaine

With epi

Answer 28

4.5 mg/kg plain

7 mg/kg w/ epi

Question 29

Max dosage prilocaine

Answer 29

8 mg/kg

Question 30

Intralipid dosage

Answer 30

1.5 ml/kg of 20% intralipid followed by infusion of 0.25 ml/kg