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nitroprusside or nitroferricyanide (Nipride, Nitropress [sodium salt])

Tradename: Nipride [sodium salt]. Na2 Fe [(CN)5 NO]. Indications: IV sodium nitroprusside is indicated in: 1) the treatment of moderate to severe hypertension - results in a prompt reduction in blood pressure by dilation of the venous & arterial circulation 2) hypertensive encephalopathy - drug of choice 3) acute cardiogenic pulmonary edema 4) aortic dissection (together with labetalol) 5) valvular regurgitation 6) acute renal insufficiency 7) microangiopathic hemolytic anemia 8) severe hypertensive retinopathy with any evidence of end organ damage 9) acute mitral regurgitation or aortic regurgitation with acute heart failure Contraindications: 1) pregnancy: cyanide & thiocyanate cross the placenta 2) decreased cerebral perfusion 3) arteriovenous shunt 4) coarctation of the aorta 5) increased intracranial pressure - may increase intracranial pressure Caution: 1) severe renal insufficiency 2) hepatic failure 3) hypothyroidism 4) hyponatremia 5) myocardial ischemia due to potential reduction in regional myocardial blood flow "coronary steal" Dosage: 1) solutions should be prepared in 5% dextrose & water just before use & shielded from light because the drug is photosensitive. 2) 50 mg in 250 mL D5W (200 ug/mL) 3) initial dose is 10-15 ug/min (or 0.25 ug/kg/min) administered as a continuous IV infusion, increasing by 5-10 ug/min increments every 5-10 min as required for control of BP [2]. 4) start at 0.3 ug/kg/min (for 70 kg adult = 6 mL/hr), max 10 ug/kg/min 5) the maximum dose of 10 ug/kg/min should never be used for more than 10 minutes Powder for injection: 50 mg. Pharmacokinetics: 1) onset of action occurs within 1 minute 2) peak effect in 1-2 minutes 3) blood pressure returns to baseline within 2-10 minutes after discontinuing drug 4) elimination: via erythrocyte uptake - metabolized by a reaction with hemoglobin, resulting in cyanmethemoglobin & an unstable intermediate that dissociates, releasing cyanate 5) cyanate is converted to thiocyanate which is excreted by the kidneys 6) thiocyanate may accumulate in patients with renal dysfunction or with high infusion rates for prolonged periods 7) 1/2life for nitroprusside is 2 minutes Monitor: - intensive cardiac monitoring [6] - therapeutic monitoring: - plasma thiocyanate levels should be monitored with prolonged therapy (> 72 hours) Adverse effects: 1) not common (1-10%) - excessive hypotensive response, sweating, palpitations, restlessness, weakness, disorientation, psychosis, headache, thyroid suppression, nausea/vomiting, muscle spasm, tinnitus, substernal distress, hypoxia, methemoglobinemia, decreased platelet aggregation 2) other - cyanide also released is metabolized in the liver by rhodanese to form thiocyanate - manifestations of thiocyanate toxicity - effects caused by too rapid an infusion - nausea/vomiting - diaphoresis - nasal stuffiness - retrosternal discomfort - palpitations - dizziness - abdominal pain Overdose: - nitroglycerin for management of hypertension - sodium thiosulfate - hydroxycobalamin (Cyanokit) Drug interactions: - additive effects when used in combination with ganglionic blocking agents, negative inotropic agents, general anesthetics, & other circulatory depressants Laboratory: - nitroprusside in serum/plasma - nitroprusside reacting substances in urine Mechanism of action: 1) when nitroprusside comes into contact with erythrocytes, the molecule decomposes, releasing nitric oxide (NO) 2) modest reductions in total peripheral resistance 3) more active on veins than arteries 4) reflex tachycardia 5) slight decrease in cardiac output, due to peripheral blood pooling 6) decrease in preload 7) some decrease in afterload 8) decrease in systemic vascular resistance (SVR) & peripheral vascular resistance (PVR)

Interactions

drug interactions drug adverse effects of antihypertensive agents

Related

cyanide (CN-) methemoglobinemia thiocyanate

General

anion vasodilator agent

Properties

MISC-INFO: elimination route ERYTHROCYTE onset-of-action 1-2 MIN {IV} 1/2life 1-3 MIN pregnancy-category C safety in lactation -

Database Correlations

PUBCHEM correlations

References

  1. Gilman et al, eds. Permagon Press/McGraw Hill pg 803
  2. Manual of Medical Therapeutics, 28th ed, Ewald & McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 107
  3. The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
  4. Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998 Department of Veterans Affairs, VA National Formulary
  5. Kaiser Permanente Northern California Regional Drug Formulary, 1998
  6. Medical Knowledge Self Assessment Program (MKSAP) 17, American College of Physicians, Philadelphia 2015