Brands, Medical Use, Clinical Data
- Antihypertensive Agents
- Vasodilator Agents
Brands / Synonyms
Disodium nitroprusside dihydrate; Nipride; Nitropress; Sodium nitroferricyanide dihydrate; Sodium Nitroprusside; Sodium nitroprusside dihydrate; sodium nitroprusside extra pure; sodium nitroprusside gr
; Sodiun nitroferricyanide dihydrate
For immediate reduction of blood pressure of patients in hypertensive crises, reduce bleeding during surgery, and for the treatment of acute congestive heart failure
Nitroprusside a powerful vasodilator relaxes the vascular smooth muscle and produce consequent dilatation of peripheral arteries and veins. Other smooth muscle (e.g., uterus, duodenum) is not affected. Sodium nitroprusside is more active on veins than on arteries.
Mechanism of Action
One molecule of sodium nitroprusside is metabolized by combination with hemoglobin to produce one molecule of cyanmethemoglobin and four CN- ions; methemoglobin, obtained from hemoglobin, can sequester cyanide as cyanmethemoglobin; thiosulfate reacts with cyanide to produce thiocyanate; thiocyanate is eliminated in the urine; cyanide not otherwise removed binds to cytochromes. Cyanide ion is normally found in serum; it is derived from dietary substrates and from tobacco smoke. Cyanide binds avidly (but reversibly) to ferric ion (Fe+++), most body stores of which are found in erythrocyte methemoglobin (metHgb) and in mitochondrial cytochromes. When CN is infused or generated within the bloodstream, essentially all of it is bound to methemoglobin until intraerythrocytic methemoglobin has been saturated.
Biotrnasformation / Drug Metabolism
Metabolized by reaction with hemoglobin to produce cyanmethemoglobin and cynide ions
Sodium nitroprusside should not be used in the treatment of compensatory hypertension, where the primary
hemodynamic lesion is aortic coarctation or arteriovenous shunting.
Sodium nitroprusside should not be used to produce hypotension during surgery in patients with known inadequate
cerebral circulation, or in moribund patients (A.S.A. Class 5E) coming to emergency surgery.
Patients with congenital (Leber's) optic atrophy or with tobacco amblyopia have unusually high cyanide!
thiocyanate ratios. These rare conditions are probably associated with defective or absent rhodanase, and sodium
nitroprusside should be avoided in these patients.
Sodium nitroprusside should not be used for the treatment of acute congestive heart failure associated with
reduced peripheral vascular resistance such as high-output heart failure that may be seen in endotoxic sepsis.
The hypotensive effect of sodium nitroprusside is augmented by that of most other hypotensive drugs, including
ganglionic blocking agents, negative inotropic agents, and inhaled anesthetics.