Ex 1 Barbs Slides

Question 1

Sedative hypnotic effects of barbiturates result from what?

Answer 1

Substitutions at the 2 and 5 carbon atoms of barbaturic acid

Question 2

A branched chain on 5 results in

Answer 2

Greater hypnotic activity than straight chain

Question 3

Phenol group on 5 results in

Answer 3

Enhanced anticonvulsant activity

Question 4

Methyl radical on barbituric acid

Answer 4

Pro-convulsive effects

***Methohexital

Question 5

Oxygen on 2 of barbaturic acid

Answer 5

Oxybarbiturates

** Methohexital, Pentobarbital

Question 6

Sulfur on 2 results in

Answer 6

Thiobarbiturates - greater lipid solubility, faster onset, greater potency, shorter DOA
**Thiopental

Question 7

Barbiturates MOA

Answer 7

Sedative, hypnotic via GABA-A (increase affinity of GABA for its receptor)
Increased Cl- conductance (directly activates Cl- channel) and hyperpolarizes post-synaptic cell

Question 8

Distribution is dependent on

Answer 8

Lipid solubility — MOST
Protein binding
Degree of ionization
Tissue blood flow

Question 9

Metabolism of oxybarbiturates

Answer 9

** methohexital, pentobarbital
Only in hepatocytes
Metabolites inactive/H20 soluble

Question 10

Metabolism of thiobarbs

Answer 10

** Thiopental
Hepatocytes & extraheptic (kidney, CNS)
Metabolites inactive/H2O soluble

Question 11

Most important step in terminating pharmacological activity in barbiturates

Answer 11

Oxidation of 5 carbon to carboxylic acid

Question 12

Prolonged DOA means what?

Answer 12

Extreme hepatic dysfunction

Question 13

STP is primarily metabolized in ______

Answer 13

Liver by CYP

Cirrhosis does not alter clearance

Question 14

_____ metabolism is more rapid than _____

Answer 14

Methohexital

STP

Question 15

STP induction dose

Answer 15

3-5mg/kg IV

Dose decreased with age/pregnancy

Question 16

Pediatric induction dose STP

Answer 16

5-6mg/kg IV

Question 17

Methohexital IV induction dose

Answer 17

1-1.5 mg/kg

Question 18

Methohexital pediatric induction IV

Answer 18

1-2 mg/kg

Question 19

Awakening from barbs are dependent on

Answer 19

Redistribution not metabolism

Question 20

CNS effects

Answer 20

Tx of increased ICP in combo w/ hyperventilation and diuresis
-decreased CBF/CMRO2

Question 21

STP CV effects

Answer 21

Transient hypotension d/t decreased preload 
Increased HR (d/t baroreceptors)

Question 22

STP additional CV effects

Answer 22

Histamine release - rapid IVP

Profound hypotension, bronchoconstriction

Question 23

STP ventilation effects

Answer 23

Dose dependent depression of ventilation
Shifts CO2 curve to the right (decreased sensitivity)
Decreased RR, VT

Question 24

What may occur if barb dose inadequate?

Answer 24

Laryngospasm/bronchospasm

Question 25

STP Liver effects

Answer 25

Decreased hepatic blood flow (related to BP)

CYP induction after 2-7d

Question 26

How long will CYP induction persist after d/c?

Answer 26

30 days

Question 27

Which Rx is most potent CYP inducer?

Answer 27

Phenobarb

Question 28

As a result of the CYP inducer effect, what may happen to other drugs?

Answer 28

Other drugs are cleared more quickly

Question 29

AE of barbs

Answer 29

Acute intermittent porphyria

Question 30

S/S of AE

Answer 30

AIP- abd pain, constipation, muscular weakness, seizures, severe N/V