nitroprusside or nitroferricyanide (Nipride, Nitropress [sodium salt])
Jump to navigation
Jump to search
Introduction
Tradename: Nipride [sodium salt]. Na2 Fe [(CN)5 NO].
Indications
IV sodium nitroprusside is indicated in:
- the treatment of moderate to severe hypertension
- results in a prompt reduction in blood pressure by dilation of the venous & arterial circulation
- hypertensive encephalopathy
- drug of choice
- acute cardiogenic pulmonary edema
- aortic dissection (together with labetalol)
- valvular regurgitation
- acute renal insufficiency
- microangiopathic hemolytic anemia
- severe hypertensive retinopathy with any evidence of end organ damage
- acute mitral regurgitation or aortic regurgitation with acute heart failure
Contraindications
- pregnancy: cyanide & thiocyanate cross the placenta
- decreased cerebral perfusion
- arteriovenous shunt
- coarctation of the aorta
- increased intracranial pressure
- may increase intracranial pressure
Caution:
- severe renal insufficiency
- hepatic failure
- hypothyroidism
- hyponatremia
- myocardial ischemia due to potential reduction in regional myocardial blood flow "coronary steal"
Dosage
- solutions should be prepared in 5% dextrose & water just before use & shielded from light because the drug is photosensitive.
- 50 mg in 250 mL D5W (200 ug/mL)
- 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].
- start at 0.3 ug/kg/min (for 70 kg adult = 6 mL/hr), max 10 ug/kg/min
- the maximum dose of 10 ug/kg/min should never be used for more than 10 minutes
Powder for injection: 50 mg.
Pharmacokinetics
- onset of action occurs within 1 minute
- peak effect in 1-2 minutes
- blood pressure returns to baseline within 2-10 minutes after discontinuing drug
- elimination: via erythrocyte uptake
- metabolized by a reaction with hemoglobin, resulting in cyanmethemoglobin & an unstable intermediate that dissociates, releasing cyanate
- cyanate is converted to thiocyanate which is excreted by the kidneys
- thiocyanate may accumulate in patients with renal dysfunction or with high infusion rates for prolonged periods
- 1/2life for nitroprusside is 2 minutes
elimination via erythrocyte
1/2life = 1-3 min
Monitor
- intensive cardiac monitoring[6]
- therapeutic monitoring:
- plasma thiocyanate levels should be monitored with prolonged therapy (> 72 hours)
Adverse effects
- 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
- 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
- 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
Mechanism of action
- when nitroprusside comes into contact with erythrocytes, the molecule decomposes, releasing nitric oxide (NO)
- modest reductions in total peripheral resistance
- more active on veins than arteries
- reflex tachycardia
- slight decrease in cardiac output, due to peripheral blood pooling
- decrease in preload
- some decrease in afterload
- decrease in systemic vascular resistance (SVR) & peripheral vascular resistance (PVR)
More general terms
Additional terms
References
- ↑ Gilman et al, eds. Permagon Press/McGraw Hill pg 803
- ↑ 2.0 2.1 Manual of Medical Therapeutics, 28th ed, Ewald & McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 107
- ↑ The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
- ↑ 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
- ↑ Kaiser Permanente Northern California Regional Drug Formulary, 1998
- ↑ 6.0 6.1 Medical Knowledge Self Assessment Program (MKSAP) 17, American College of Physicians, Philadelphia 2015