phenylephrine (neo-synephrine)

The Pure Squeezer

Pure ${\alpha }_1$-agonist for anesthesia-induced hypotension and tachyarrhythmias. Avoid in cardiogenic shock (increases afterload without inotropy).

• Mechanism: Pure ${\alpha }_1$-agonist. Minimal/no $\beta$ activity.

• Dosing: Anesthesia: 50-200 mcg IV bolus. Infusion: 0.5-5 mcg/kg/min.

• PK: Onset: Immediate. Duration: Short (minutes).

indications

• Anesthesia-Induced Hypotension – Primary indication
• Tachyarrhythmias – e.g., AFib with RVR + Shock

cautions

• Cardiogenic Shock: Increasing afterload without increasing contractility will crush the failing LV and drop Cardiac Output further
• Reflex Bradycardia: Baroreceptor mediated drop in HR

clinical pearl

Useful in “Left Ventricular Outflow Obstruction” (HOCM / SAM) where you want high afterload (to stent the LVOT open) and slow HR (to increase filling).