Nitroprusside Sodium
disodium (OC-6-22)pentakis(cyano-C)nitrosylferrate dihydrate
Also known as: Nitropress · natrii nitroprussias · sodium nitroferricyanide dihydrate · sodium nitroprussiate
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Hypertensive crisis (systolic arterial BP >200 mm Hg) | Initiate dose at 1-2 micrograms/kg/minute; increase dosage incrementally every 3-5 minutes until a predetermined target BP is attained. Reduce BP 25% over 4-hour period to allow readaptation of cerebral blood vessels. | IV | CRI | Titrate to effect | 🌎 NA |
| Adjunctive treatment of heart failure (cardiogenic shock; fulminant pulmonary edema) | Initiate dose at 1-2 micrograms/kg/minute; increase dosage incrementally every 3-5 minutes. Goal is to decrease or maintain mean arterial pressure to support vital organ functions-approx. 70 mmHg. | IV | CRI | Titrate to effect | 🌎 NA |
| Adjunctive treatment of heart failure | 0.5-10 micrograms/kg/min IV at a low fluid rate (2 mL/kg/hr) using D5W or other low sodium fluid. Usually start at 2 micrograms/kg/min and increase the base concentration by 1 microgram/kg every 20-30 minutes until there is an improvement in respiratory effort and thoracic auscultation. | IV | CRI | Maintain effective dose for 48 hours | 🌎 NA |
| Catastrophic pulmonary edema | As a CRI initiated at 1 microgram/kg/min and carefully titrated to effect by increasing by 1 microgram/kg/min increments every 15 minutes as long as BP remains stable and until perfusion and pulmonary function improves (usually requires between 2-5 micrograms/kg/min with the upper limit being 8-10 micrograms/kg/min). | IV | CRI | Maintain most effective dose for 12-15 hours | 🌎 NA |
- Adjunctive treatment of heart failure (cardiogenic shock; fulminant pulmonary edema): Concurrent use of dobutamine (5-10 micrograms/kg/min) often indicated.
- Adjunctive treatment of heart failure: Monitor blood pressure; cyanide poisoning can occur if infusion lasts more than 3 days. Taper drip as enalapril is initiated.
- Catastrophic pulmonary edema: Systolic BP must remain >90 mm Hg. Wean nitroprusside over 6 hours first, then dobutamine over 6 hours.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Hypertensive crisis (systolic arterial BP >200 mm Hg) | Initiate dose at 0.5 micrograms/kg/minute; increase dosage incrementally every 3-5 minutes until a predetermined target BP is attained. Reduce BP 25% over 4-hour period to allow readaptation of cerebral blood vessels. | IV | CRI | Titrate to effect | 🌎 NA |
| Adjunctive treatment of heart failure (cardiogenic shock; fulminant pulmonary edema) | Initiate dose at 0.5 micrograms/kg/minute; increase dosage incrementally every 3-5 minutes. Goal to decrease or maintain mean arterial pressure to support vital organ functions-approx. 70 mmHg. | IV | CRI | Titrate to effect | 🌎 NA |
| Adjunctive treatment of heart failure | Initiate dose at 0.5 micrograms/kg/minute constant rate infusion and increase by 0.5-1 microgram/minute every 5 minutes to desired systolic pressure (90-100 mmHg). | IV | CRI | Titrate to effect | 🌎 NA |
| Catastrophic pulmonary edema | As a CRI initiated at 1 microgram/kg/min and carefully titrated to effect by increasing by 1 microgram/kg/min increments every 15 minutes as long as BP remains stable and until perfusion and pulmonary function improves (cats usually requires between 1-2 micrograms/kg/min with the upper limit being 2 micrograms/kg/min). | IV | CRI | Maintain most effective dose for 12-15 hours | 🌎 NA |
- Adjunctive treatment of heart failure (cardiogenic shock; fulminant pulmonary edema): Concurrent use of dobutamine (1-5 micrograms/kg/min) often indicated.
- Adjunctive treatment of heart failure: Cats are more sensitive to oxidative damage; keep total dosages to a minimum. Use dedicated line; never flush.
- Catastrophic pulmonary edema: Systolic BP must remain >90 mm Hg. Wean nitroprusside over 6 hours first, then dobutamine over 6 hours.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Nitroprusside sodium is a highly potent, ultra-short-acting mixed vasodilator used exclusively in intensive care settings.
Key clinical highlights:
- Primary Indications: Management of hypertensive crises, acute heart failure secondary to severe mitral regurgitation, and refractory congestive heart failure (CHF).
- Hemodynamic Effects: Rapidly reduces both preload and afterload by relaxing arterial and venous smooth muscle.
- Clinical Pearl: Because of its profound hypotensive effects and ultra-short half-life, it must be administered as a Constant Rate Infusion (CRI) with continuous direct arterial blood pressure monitoring.
- Toxicity Risk: Prolonged use (>48-72 hours) or high doses can lead to accumulation of toxic metabolites (cyanide and thiocyanate), especially in patients with renal or hepatic impairment.
Mechanism of action
Nitroprusside acts as a nitric oxide (NO) donor.
- Once in the bloodstream, it interacts with tissue sulfhydryl groups to release NO.
- NO activates the enzyme soluble guanylate cyclase in vascular smooth muscle cells.
- This leads to an increase in intracellular cyclic guanosine monophosphate (cGMP).
- Elevated cGMP activates protein kinase G, which reduces intracellular calcium concentrations → vascular smooth muscle relaxation.
This mechanism causes direct peripheral vasodilation of both arterioles and venules (independent of autonomic innervation), resulting in:
- Lowered blood pressure
- Significant reduction in total peripheral resistance (afterload)
- Reduced left ventricular end-diastolic pressure (preload)
- Mild decrease in cardiac output (though in severe heart failure, CO may actually increase due to afterload reduction)
- Reflex tachycardia (increase in heart rate)
Safety & warnings
Contraindications
- Compensatory hypertension (e.g., AV shunts, coarctation of the aorta, Cushing's reflex)
- Inadequate cerebral circulation
- Emergency surgery in patients near death
Adverse effects
- Profound hypotension
- Nausea
- Retching
- Restlessness
- Apprehension
- Muscle twitching
- Dizziness
- Infusion site irritation (avoid extravasation)
- Thiocyanate and cyanide toxicity (with prolonged use)
Precautions
CRITICAL WARNING: Must only be used in an ICU setting with continuous blood pressure monitoring.
- Organ Impairment: Use with extreme caution in patients with hepatic insufficiency, severe renal impairment, hyponatremia, or hypothyroidism due to increased risk of thiocyanate/cyanide toxicity.
- Surgical Use: When used for controlled hypotension during surgery, patients have less tolerance to hypovolemia, anemia, or blood loss.
- Geriatrics: Older patients may be more sensitive to hypotensive effects.
- Pregnancy: FDA Category C. Animal studies show adverse fetal effects. Use cautiously as a last resort when benefits clearly outweigh risks. Unknown if excreted in milk.
Drug interactions
May enhance the hypotensive effects of nitroprusside.
Synergistic effects (increased cardiac output and reduced wedge pressure) may result; often used together beneficially in severe heart failure.
Patients may be more sensitive to the hypotensive effects of nitroprusside.
Monitoring
- Blood pressure (constant, direct arterial monitoring preferred)
- Acid/base balance (to detect early metabolic acidosis/cyanide toxicity)
- Electrolytes (especially Na+)
- Respiratory effort and thoracic auscultation
- Serum thiocyanate levels (if on prolonged therapy or concurrent renal dysfunction)
Pharmacokinetics
Half-life
Absorption
Immediate onset of action following IV infusion. Blood pressure returns to pretreatment levels within 1-10 minutes following cessation of therapy.
Distribution
Rapidly distributed in the bloodstream.
Metabolism
Metabolized non-enzymatically in the blood and tissues to cyanogen (cyanide radical). Cyanogen is then converted in the liver to thiocyanate.
Elimination
Eliminated in the urine, feces, and exhaled air.
Overdose
Acute Overdosage: Manifests as profound hypotension.
- Treatment: Reduce or stop the infusion and administer IV fluids. Blood pressure will typically recover within 1-10 minutes. Monitor BP constantly.
Toxicity (Cyanide/Thiocyanate): Excessive doses, prolonged therapy (>3 days), depleted hepatic thiosulfate, or severe hepatic/renal insufficiency may lead to cyanogen or thiocyanate toxicity.
- Signs: Metabolic acidosis (early sign of cyanogen toxicity), tolerance to therapy, delirium (thiocyanate toxicity in dogs).
- Monitoring: Monitor acid/base status. Serum thiocyanate levels >100 mcg/mL are considered toxic.
- Treatment: Hydroxocobalamin (Vitamin B12a) may prevent or treat cyanogen toxicity. Contact an animal poison control center for specific antidotal protocols if suspected.
Available products
Formulations
- Powder for injection
Human-labeled
- Nitroprusside Sodium Powder for Injection: 50 mg/vial in 2 mL and 5 mL vials (Nitropress)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store powder protected from light and moisture at room temperature (15-30°C). Reconstitute ONLY with 5% Dextrose in Water (D5W). Immediately protect the reconstituted solution from light using aluminum foil or an opaque cover. Stable for 24 hours after reconstitution. Discard any solution that turns blue, dark red, or green (indicates degradation and loss of potency). Do not add any other medications to the IV line running nitroprusside.
Client information
Intensive Care Medication
- This medication is strictly for use by veterinary professionals in an Intensive Care Unit (ICU) setting.
- It requires precise intravenous delivery via a specialized pump and continuous, minute-by-minute monitoring of your pet's blood pressure.
- It is a life-saving drug used to rapidly stabilize pets in severe heart failure or experiencing dangerously high blood pressure crises.
- Because it is so potent, the veterinary team will monitor your pet closely for any signs of low blood pressure or side effects from the medication's breakdown products.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.