Barbituates

Question 1

Thiopental

Answer 1

MOA: potentiate GABA-A receptor function by increasing length of time channel stays open upon stimulation by GABA

Use: brief anesthesia

PK: ultrashort duration (minutes); lipophillic (enters brain rapidly then re-distributes)

CI: porphyria (induce delta ALA synthetase)

Question 2

Secobarbital

Answer 2

MOA: potentiate GABA-A receptor function by increasing length of time channel stays open upon stimulation by GABA

Use: pre-anesthetic sedation, hypnotic, tolerance develops

PK: intermediate duration (hours)

CI: porphyria (induce delta ALA synthetase)

Question 3

Phenobarbital

Answer 3

MOA: potentiate GABA-A receptor function by increasing length of time channel stays open upon stimulation by GABA

Use: daytime sedation, anticonvulsant, tolerance does not develop

PK: long duration (hrs/days)

SE: suppress beta rhythm activity and disrupt REM sleep – can interfere with daytime mental function

CI: porphyria (induce delta ALA synthetase)

Question 4

Effects of Barbiturate Abuse

Answer 4

overdose signs = respiratory depression, decreased body temperature

Losw dose: sedation, euphoria, loss of inhibition

Medium dose: pleasurable intoxication, decreased activity, drowsiness

High dose: severe intoxication, intense emotions, sleep

Question 5

Barbiturate Toxicity

Answer 5

Low dose: nausea, hangover

Medium dose: hangover, respiratory depression, decrease BP/HR –> effects develop tolerance and narrow the TI

High dose: respiratory depression, coma, decreased body temperature