Labetalol

Question 1

What is the pharmacologic category/class of labetalol

Answer 1

Class

• Nonselective beta-1 & 2 adrenergic antagonist
• Selective alpha-1 antagonist

_{Anesthesia Guidebook - Episode 18: Anesthesia Top Drawer Run Down - Part 2
UpToDate - Labetalol: Drug Information}

Question 2

What is the mechanism of action of metoprolol?

Answer 2

SA nodal cells: inhibits cAMP mediated sodium & calcium conductance during phase 4 of the action potential → ↓ chronotropy

Cardiac myocytes: inhibits cAMP mediated calcium conductance → ↓ inotropy

_{Anesthesia Guidebook - Episode 18: Anesthesia Top Drawer Run Down - Part 2
UpToDate - Metoprolol: Drug Information}

Question 3

What is the typical intraoperative dose of metoprolol?

Answer 3

• 2-5 mg IV

may repeat dosing q5 minutes to a max dose of 15 mg

_{Anesthesia Guidebook - Episode 18: Anesthesia Top Drawer Run Down - Part 2}

Question 4

What is the onset of action for metoprolol?

Answer 4

• ~5 minutes

_{Anesthesia Guidebook - Episode 18: Anesthesia Top Drawer Run Down - Part 2}

Question 5

What is the duration of action for metoprolol?

Answer 5

• ~3-8 hours

_{Anesthesia Guidebook - Episode 18: Anesthesia Top Drawer Run Down - Part 2}

Question 6

What organ(s) are responsible for metoprolol’s clearance (metabolism/elimination)?

Answer 6

• Metabolism: Liver (P450)
• Elimination: Kidneys

_{Anesthesia Guidebook - Episode 18: Anesthesia Top Drawer Run Down - Part 2}