Nitroprusside

Background

• Sodium nitroprusside is primarily used as a potent vasodilator.
• Works predominantly in arterioles and venules as a result of its breakdown to nitric oxide (NO).
• Nitric oxide reduces both total peripheral resistance and venous return, thus decreasing both preload and afterload
• Thiocyanate level when checking for toxicity

Adult Dosing

• Start 0.5 mcg/kg/min IV, increasing 0.5 mcg/kg/min q5 min
• Usual dosage 3-4 mcg/kg/min IV
• Max dose 10 mcg/kg/min for 10 min

Pediatric Dosing

• Start 0.3 mcg/kg/min IV, max 10 mcg/kg/min for 10 min

Contraindications

• Pregnancy
• ICH - theoretical concern for raising ICP via cerebral vasodilation, consider nicardipine instead
• Aortic coarctation
• Arteriovenous shunt
• Existing cyanide toxicity
• High output heart failure
• Lack of arterial line monitoring

Maximum Dose Rate

• Infusion at maximum dose rate of 10 mcg/kg/min should never last for more than 10 minutes
• If blood pressure is not controlled after 10 minutes of infusion at max rate, immediately terminate infusion

Indications

• Hypertensive emergency
• CHF, low output

Mechanism of Action

Potent arteriolar dilation from its active metabolite, nitric oxide (NO).

Adverse Drug Reactions

• Cyanide toxicity

Kinetics

• Cyanide and thiocyanate metabolites potentially toxic
• Metabolized via liver CYP450, excreted via urine
• Half life 2 min
• However, thiocyanate half life is 3 days