PreOp Meds: Diazepam

Question 1

Why does diazepam burn on injection?
Is there a better formulation?

Answer 1

• insoluble in water so it’s dissolved in propylene glycol.
• Soybean formulation available but more expensive.

Question 2

What is the onset of diazepam?
What is the E ½ time of diazepam?
What is the Vd of diazepam?

Answer 2

• Onset: 1-5 minutes
• E ½ = 20-40 hours (very protein-bound)
• Vd = 1-1.5 L/kg

Question 3

What metabolizes diazepam?
What are its primary metabolites and what is it’s significance?

Answer 3

• CYP3A4
• Desmethyldiazepam & oxazepam
• Metabolites are nearly as potent as diazepam and hit 6-8 hours after administration.

Question 4

What is the seizure dosing for diazepam?
What seizures is it utilized for?

Answer 4

• 0.1 mg/kg IV
• DT’s, status epilepticus, lidocaine toxicity seizures.

Question 5

What are the EEG effects of diazepam?

Answer 5

• Can produce isoelectric EEG.

Question 6

What are the pulmonary effects of diazepam?

Answer 6

• Minimal; any depressant effects are reversed by surgical stimulation.

Question 7

What are diazepam’s effects on the cardiovascular system?
What effects would be seen with adjunct opioids?

Answer 7

• Minimal decreases in BP, CO, and SVR (used be agent for cardiac cases)
• Additive BP changes when used with opioid.

Question 8

What are diazepam’s effects on the musculoskeletal system?

Answer 8

• Decreases skeletal muscle tone

Question 9

What is the induction dose of diazepam?
When would one decrease the dose by 50%?

Answer 9

• 0.5-1 mg/kg IV
• 50% cut with elderly, liver patients, and with concurrent opioid use.