Sodium nitroprusside
From Wikipedia, the free encyclopedia
 |
|
|
Sodium nitroprusside
|
|
| Systematic (IUPAC) name | |
| disodium; iron; oxoazanide; pentacyanide | |
| Identifiers | |
| CAS number | 13755-38-9 |
| ATC code | C02DD01 |
| PubChem | 26256 |
| DrugBank | APRD01143 |
| Chemical data | |
| Formula | Na2[Fe(CN)5NO] |
| Mol. weight | 261.92 |
| Pharmacokinetic data | |
| Bioavailability | ? |
| Metabolism | ? |
| Half life | 2 minutes (metabolites: several days) |
| Excretion | ? |
| Therapeutic considerations | |
| Pregnancy cat. |
? |
| Legal status | |
| Routes | ? |
| Sodium nitroprusside | |
|---|---|
 |
|
| General | |
| Systematic name | Sodium pentacyanonitrosylferrate(III) |
| Other names | Sodium nitroprusside Sodium nitroferricyanide Sodium pentacyanonitrosylferrate SNP |
| Molecular formula | Na2[Fe(CN)5NO]·2H2O |
| Molar mass | 261.92 g mol−1 |
| Appearance | red powder |
| CAS number | [13755-38-9] |
| Properties | |
| Solubility in water | good |
| Other solvents | soluble in Ethanol |
| Structure | |
| Coordination geometry |
octahedral at Fe |
| Main hazards | non-hazardous |
| R/S statement | R: 25 S: 45 |
| RTECS number | LJ8750000 |
Sodium nitroprusside is the chemical compound Na2[Fe(CN)5NO]. It is a potent peripheral vasodilator that affects both arterioles and venules. Sodium nitroprusside is often administered intravenously to patients who are experiencing a hypertensive emergency.
Contents |
[edit] Chemistry
"Nitroprusside" is an anion that is usually available as the dihydrate of its disodium salt, Na2[Fe(CN)5NO]·H2O. This red solid dissolves in water, and to a lesser extent in alcohol to give a solution containing the [Fe(CN)5NO]2−. This metal nitrosyl complex is the active agent. In this anion, the iron is octahedral, surrounded by five tightly bound cyanide ligands and one nitric oxide ligand.
[edit] Indications
It reduces both total peripheral resistance as well as venous return, thus decreasing both preload and afterload. For this reason, it can be used in severe cardiogenic heart failure where this combination of effects can act to increase cardiac output. In situations where cardiac output is normal; the effect is to reduce blood pressure.
Nitroprusside is light-sensitive, and breaks down in sunlight, producing cyanide.
Despite its toxicity, nitroprusside is still used because it remains an effective drug in certain clinical circumstances such as malignant hypertension or for rapid control of blood pressure during vascular surgery and neurosurgery.
[edit] Mechanism of action
Its mechanism of action appears to be liberation of nitric oxide (NO) as it is metabolised in the erythrocyte, converting Haemoglobin to cyanomethaemaglobin. Nitroprusside also releases cyanide ions which are converted in the liver to thiocyanate by the enzyme rhodanase, a reaction which requires a sulfur donor such as thiosulfate. Thiocyanate is then excreted by the kidney. In the absence of sufficient thiosulfate, cyanide ions can quickly reach toxic levels.
The half-life of nitroprusside is less than 10 minutes although thiocyanate has an excretion half life of several days. The duration of treatment should not exceed 72 hours and thiocyanate plasma concentrations should be monitored.
[edit] Role in research
Sodium nitroprusside (often abbreviated SNP) is frequently used in vascular research to test endothelium-independent vasodilation. One method of administering SNP is by iontophoresis. This allows local administration of the drug, preventing the systemic effects listed above but still causing local microvascular vasodilation. NO liberated from the SNP diffuses into the vascular smooth muscle causing relaxation and subsequent vasodilatation. This vasodilatation is quantified by various techniques.
[edit] Reference
A. R. Butler, I. L. Megson (2002). "Non-Heme Iron Nitrosyls in Biology". Chem. Rev. 102: 1155-1165. DOI:10.1021/cr000076d.
| Antihypertensives (C02) and diuretics (C03) edit | ||
|---|---|---|
| Antiadrenergic agents (including alpha): |
Clonidine, Doxazosin, Guanethidine, Guanfacine, Lofexidine, Mecamylamine, Methyldopa, Moxonidine, Prazosin, Rescinnamine, Reserpine |
|
| Vasodilators: |
Diazoxide, Hydralazine, Minoxidil, Nitroprusside, Phentolamine |
|
| Other antihypertensives: | ||
| Low ceiling diuretics: |
Bendroflumethiazide, Chlorothiazide, Chlortalidone, Hydrochlorothiazide, Indapamide, Quinethazone, Mersalyl, Metolazone, Theobromine |
|
| High ceiling diuretics: | ||
| Potassium-sparing diuretics: | ||
