Nitroprusside

Sodium Nitroprusside (Nipride®)

Class:
  • Potent vasodilator
Actions:
  • converts to nitric oxide, a potent vasodilator
  • Venous dilation reducing preload
  • Arteriolar dilation reducing afterload
  • Triggers retention of sodium and water
  • Minimal reflex tachycardia
Indications:
  • Hypertensive emergencies
  • To reduce afterload in heart failure or acute mitral valve regurgitation
  • Controlled hypotension during anesthesia to reduce bleeding
Pharmacokinetics:
  • Onset: 1 – 2 minutes after initiation of infusion or change of rate
  • Half-Life:  less than 10 minutes after discontinuation of infusion
  • Metabolism:  Nitroprusside is converted to nitric oxide in smooth muscle releasing 5 cyanide molecules which are converted in the liver to thiocyanate.
Adverse Effects:
  • Excessive hypotension, nausea, vomiting, light-headedness, headache, sweating
  • Diaphoresis, apprehension, muscle twitching, nasal stuffiness
  • Irritation at infusion site
Signs of Toxicity:
  • Precipitous drop in blood pressure
  • Thiocyanate toxicity: tinnitis, blurred vision, fatigue, metabolic acidosis, pink skin color, loss of reflexes, disorientation, psychotic behavior, delirium
Contraindications:
  • Compensatory hypertension (e.g., atriovenous shunt, coarctation of aorta
  • Use caution if patient has taken phosphodiesterase inhibitor (e.g., sildenafil)
  • Safety during pregnancy or lactation not established
Dosages & Routes:
  • IV Infusion:  50 or 100 mg in 250 ml D5W continuous infusion beginning at 0.1 mcg/kg/min and titrating every 3 – 5 minutes according to desired blood pressure up to a dose of 5 – 10 mcg/kg/min
Nursing Implications:
  • Drug Interactions:  Potential hypotensive shock when combined with other vasodilators, caution if patient is already taking phosphodiesterase inhibitor
  • Incompatibility in IV infusion:  Not compatible with amiodarone, dobutamine, propafenone, cisatracurium, and haloperidol.
  • Check blood pressure every 3 – 5 minutes to monitor patient response to nitroprusside.
  • Evaluate serum thiocyanate level (should be < 0.1 mg/ml) if patient receives nitroprusside for more than 3 days.
  • Nitroprusside is degraded in light, so IV bag & tubing should be occlusive to light (sometimes nurses wrap IV tubing with aluminum foil).
  • Patient should be on bedrest during nitroprusside infusion.
  • Calculate IV doses carefully and double-check with another nurse or pharmacist.
  • Weigh patient daily to monitor accurate doses.

 

References:

American Heart Association. (2006). Handbook of Emergency Cardiac Care (p. 59). Salem, MA: AHA.

Dirks, J.L. (2010) Cardiovascular therapeutic management.  In L.D. Urden, K.M. Stacy, & M.E. Lough's (Eds.) Critical care nursing: Diagnosis and management (6th ed., p. 547).  St. Louis: Mosby Elsevier.

Lehne, R.A. (2010). Pharmacology for nursing care (7th ed., pp. 491-492).  St. Louis: Saunders Elsevier.

Wilson, B.A., Shannon, M.T., Shields, K.M., & Stang, C.L. (2007).  Prentice Hall Nurse's Drug Guide 2007 (pp. 1174-1176).  Upper Saddle River, NJ: Pearson Prentice Hall.

 

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