Classification: vasodilator
  • relaxes arterial and venous smooth muscle to decrease afterload and preload; afterload reduction arterial effect > venous
  • decreases pulmonary artery pressure
  • enhanced renal blood flow
  • enhanced coronary blood flow
  • antihypertensive
  • Infusions:
    • 0.5-8 mcg/kg/min
Administration: IV Infusion:
50mg/250D5W, NS or RL (maximum concentration 200mg/500mL)
  • protect from light
  • hypovolemia should be corrected concurrently with initiation of therapy
  • drug should be weaned off
Adverse Effects:
  • hypotension
  • hypovolemia
  • Toxicity: 
      • each nitroprusside molecule contains 5 cyanide molecules
      • healthy humans eliminate cyanide as follows:
      • the cyanide contained in 18 mg of nitroprusside will combine with methemoglobin for elimination
      • the cyanide from an additional 50 mg of nitroprusside is bound to thiosulfate to form thiocyanate, which is eliminated in the urine 
      • cyanide toxicity occurs when the total dose of nitroprusside exceeds the ability to eliminate the cyanide (total dose of 68 mg), or if thiosulfate stores are low (e.g. in smokers)
      • thiocyanate toxicity develops if thiocyanate elimination is impaired due to renal failure
    • Cyanide Toxicity (inhibits O2 utilization by tissues):
      • increased HR
      • metabolic acidosis
      • increased lactate despite normal Sp02
      • decreased response to drug
      • increased mixed venous O2 saturation
      • decreased oxygen extraction
      • rapidly progressive tolerance is an important early indication of cyanide toxicity
    • Thiocyanate Toxicity:
      • confusion, hallucinations, delerium
      • seizures
      • fatigue, weakness
      • pupillary constriction
      • tinnitus
      • rash
      • hypothyroidism (blocks thyroid uptake and binding of iodine)
  • renal failure, hyponatremia, hypovolemia, hypothyroidism (thiocyanate inhibits uptake and binding of iodine)
  • hepatic failure, Vitamin B12 deficiency, Leber's optic atrophy
  • sodium thiosulfate
Drug Interactions:
  • nitroprusside + dopamine/dobutamine = enhanced hemodynamic effects
Monitoring Therapy:
  • BP
  • HR, ECG
  • blood gases ( arterial and mixed venous)
  • arterial lactate ( increased in toxicity)
  • cardiac index
  • urine output
  • PWP
  • toxicity correlates with thiocyanate levels > 1.7 uM/L
CCTC Protocol:
  • May be administered by IV infusion by an approved nurse in CCTC.
  • May be titrated by an approved nurse in the CCTC.
  • Must be administered via central line.
  • Must be administered via infusion pump.
  • Should not be administered via the proximal injectate port (blue) of the Swan Ganz catheter.
  • Patient requires placement of an arterial line to monitor BP.

Lynne Kelly, Pharmacist, CCTC
Brenda Morgan, Clinical Nurse Specialist, CCTC
Last Update: August 7, 2006

LHSCHealth Professionals

Last Updated March 24, 2009 | © 2007, LHSC, London Ontario Canada