Clinical data | |
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Trade names | Nipride, Nitropress, others |
Other names | SNP |
AHFS/Drugs.com | Monograph |
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Routes of administration | Intravenous |
ATC code | |
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Pharmacokinetic data | |
Bioavailability | 100% (intravenous) |
Metabolism | By haemoglobin being converted to cyanmethaemoglobin and cyanide ions |
Onset of action | nearly immediate [3] |
Elimination half-life | <2 minutes (3 days for thiocyanate metabolite) |
Duration of action | 1 to 10 minutes [3] |
Excretion | kidney (100%; as thiocyanate) [4] |
Identifiers | |
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CAS Number | |
PubChem CID | |
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CompTox Dashboard (EPA) | |
ECHA InfoCard | 100.119.126 |
Chemical and physical data | |
Formula | C5FeN6Na2O |
Molar mass | 261.921 g·mol−1 |
3D model (JSmol) | |
Density | 1.72 g/cm3 |
Solubility in water | 100 mg/mL (20 °C) |
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Sodium nitroprusside (SNP), sold under the brand name Nitropress among others, is a medication used to lower blood pressure. [3] This may be done if the blood pressure is very high and resulting in symptoms, in certain types of heart failure, and during surgery to decrease bleeding. [3] It is used by continuous injection into a vein. [3] Onset is nearly immediate and effects last for up to ten minutes. [3]
It is available as a generic medication. [5]
Common side effects include low blood pressure and cyanide toxicity. [3] Other serious side effects include methemoglobinemia. [3] It is not generally recommended during pregnancy due to concerns of side effects. [6] High doses are not recommended for more than ten minutes. [7] It works by increasing nitric oxide levels in the blood, which increases cGMP levels in cells, and causes dilation of blood vessels. [8] [3]
Sodium nitroprusside was discovered as early as 1850 and found to be useful in medicine in 1928. [8] [9] It is on the World Health Organization's List of Essential Medicines. [10] [11] Sodium nitroprusside is light sensitive, so it needs to be shielded from light to prevent degradation. [12]
Sodium nitroprusside is intravenously infused in cases of acute hypertensive crises. [13] [14] Its effects are usually seen within a few minutes. [4]
Nitric oxide reduces both total peripheral resistance and venous return, thus decreasing both preload and afterload. So, it can be used in severe congestive 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. [13] [15] It is sometimes also used to induce hypotension (to reduce bleeding) for surgical procedures (for which it is also FDA, TGA, and MHRA labelled). [13] [14] [16]
The medication is extremely beneficial for use in medical patients because the effects of the medication will directly stop the second that it stops being infused. This is due to the metabolism of the drug, and the rapid inactivation to thiocyanate once conversion of the drug stops.
This compound has also been used as a treatment for aortic valve stenosis, [17] oesophageal varices, [18] myocardial infarction, [19] pulmonary hypertension, [20] [21] [22] respiratory distress syndrome in the newborn, [23] [24] shock, [24] and ergot toxicity. [25]
Adverse effects by incidence and severity [13] [15] [26]
Common
Unknown frequency
Serious
Sodium nitroprusside should not be used for compensatory hypertension (e.g. due to an arteriovenous stent or coarctation of the aorta). [15] It should not be used in patients with inadequate cerebral circulation or in patients who are near death. It should not be used in patients with vitamin B12 deficiency, anaemia, severe renal disease, or hypovolaemia. [15] Patients with conditions associated with a higher cyanide/thiocyanate ratio (e.g. congenital (Leber's) optic atrophy, tobacco amblyopia) should only be treated with sodium nitroprusside with great caution. [15] Its use in patients with acute congestive heart failure associated with reduced peripheral resistance is also not recommended. [15] Its use in hepatically impaired individuals is also not recommended, as is its use in cases of pre-existing hypothyroidism. [13]
Its use in pregnant women is advised against, although the available evidence suggests it may be safe, provided maternal pH and cyanide levels are closely monitored. [15] [27] Some evidence suggests sodium nitroprusside use in critically ill children may be safe, even without monitoring of cyanide level. [28]
The only known drug interactions are pharmacodynamic in nature, that is it is possible for other antihypertensive drugs to reduce the threshold for dangerous hypotensive effects to be seen. [15]
Due to its cyanogenic nature, overdose may be particularly dangerous. Treatment of sodium nitroprusside overdose includes the following: [15] [29]
Haemodialysis is ineffective for removing cyanide from the body but it can be used to remove most of the thiocyanate produced from the above procedure. [15]
The cyanide can be detoxified by reaction with a sulfur-donor such as thiosulfate, catalysed by the enzyme rhodanese. [30] In the absence of sufficient thiosulfate, cyanide ions can quickly reach toxic levels. [30] Hydroxocobalamin can be administered to reduce the risk of thiocyanate toxicity induced by nitroprusside. [31]
Species | LD50 (mg/kg) for oral administration [32] | LD50 (mg/kg) for IV administration [15] | LD50 (mg/kg) for skin administration [32] |
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Mouse | 43 | 8.4 | ? |
Rat | 300 | 11.2 | >2000 |
Rabbit | ? | 2.8 | ? |
Dog | ? | 5 | ? |
As a result of its breakdown to nitric oxide (NO), sodium nitroprusside has potent vasodilating effects on arterioles and venules (arterial more than venous), whereas other nitrates exhibit more selectivity for veins (e.g. nitroglycerin). [13] [15] [26] [33]
Sodium nitroprusside breaks down in circulation to release nitric oxide (NO). [8] It does this by binding to oxyhaemoglobin to release cyanide, methaemoglobin and nitric oxide. [8] NO activates guanylate cyclase in vascular smooth muscle and increases intracellular production of cGMP. cGMP activates protein kinase G which activates phosphatases which inactivate myosin light chains. [34] Myosin light chains are involved in smooth muscle contraction. The result is vascular smooth muscle relaxation, which allow vessels to dilate. [34] This mechanism is similar to that of phosphodiesterase 5 (PDE5) inhibitors such as sildenafil (Viagra) and tadalafil (Cialis), which elevate cGMP concentration by inhibiting its degradation by PDE5. [35]
A role for NO in various common psychiatric disorders including schizophrenia, [36] [37] [38] [39] bipolar disorder [40] [41] [42] and major depressive disorder [43] [44] [45] has been proposed and supported by several clinical findings. These findings may also implicate the potential of drugs that alter NO signalling such as SNP in their treatment. [38] [44] Such a role is also supported by the findings of the recent SNP clinical trial. [46]
Nitroprusside is an inorganic compound with the chemical formula Na2[Fe(CN)5NO], usually encountered as the dihydrate, Na2[Fe(CN)5NO]·2H2O. [47] This red-colored sodium salt dissolves in water or ethanol to give solutions containing the free complex dianion [Fe(CN)5NO]2−.
Nitroprusside is a complex anion that features an octahedral iron(II) centre surrounded by five tightly bound cyanide ligands and one linear nitric oxide ligand (Fe-N-O angle = 176.2 ° [48] ). The anion possesses idealized C4vsymmetry.
Due to the linear Fe-N-O angle, the relatively short N-O distance of 113 pm [48] and the relatively high stretching frequency of 1947 cm−1, the complex is formulated as containing an NO+ ligand. [49] Consequently, iron is assigned an oxidation state of 2+. The iron center has a diamagnetic low-spin d6 electron configuration, although a paramagnetic long-lived metastable state has been observed by EPR spectroscopy. [50]
The chemical reactions of sodium nitroprusside are mainly associated with the NO ligand. [51] For example, addition of S2− ion to [Fe(CN)5(NO)]2− produces the violet colour [Fe(CN)5(NOS)]4− ion, which is the basis for a sensitive test for S2− ions. An analogous reaction also exists with OH− ions, giving [Fe(CN)5(NO2)]4−. [49] Roussin's red salt (K2[Fe2S2(NO)4]) and Roussin's black salt (NaFe4S3(NO)7) are related iron nitrosyl complexes. The former was first prepared by treating nitroprusside with sulfur. [52]
Sodium nitroprusside can be synthesized by digesting a solution of potassium ferrocyanide in water with nitric acid, followed by neutralization with sodium carbonate: [53]
Alternatively, the nitrosyl ligand can be introduced using nitrite: [49]
Sodium nitroprusside is often used as a reference compound for the calibration of Mössbauer spectrometers. [54] Sodium nitroprusside crystals are also of interest for optical storage. For this application, sodium nitroprusside can be reversibly promoted to a metastable excited state by blue-green light, and de-excited by heat or red light. [55]
In physiology research, sodium nitroprusside is frequently used to test endothelium-independent vasodilation. Iontophoresis, for example, allows local administration of the drug, preventing the systemic effects listed above but still inducing local microvascular vasodilation. Sodium nitroprusside is also used in microbiology, where it has been linked with the dispersal of Pseudomonas aeruginosa biofilms by acting as a nitric oxide donor. [56] [57]
Sodium nitroprusside is also used as an analytical reagent under the name sodium nitroferricyanide for the detection of methyl ketones, amines, and thiols. It is also used as a catalyst in the quantitative determination of ammonia in water samples via the phenate method. [58]
The nitroprusside reaction is used for the identification of ketones in urine testing. [59] Sodium nitroprusside was found to give a reaction with acetone or creatine under basic conditions in 1882. Rothera refined this method by the use of ammonia in place of sodium or potassium hydroxide. The reaction was now specific for methyl ketones. Addition of ammonium salts (e.g. ammonium sulfate) improved the sensitivity of the test, too. [60]
In this test, known as Rothera's test, methyl ketones (CH3C(=O)-) under alkaline conditions give bright red coloration (see also iodoform test). Rothera's test was initially applied to detecting ketonuria (a symptom of diabetes) in urine samples. This reaction is now exploited in the form of urine test strips (e.g. "Ketostix"). [61]
The nitroprusside reaction is a chemical test used to detect the presence of thiol groups of cysteine in proteins. Proteins with the free thiol group give a red colour when added to a solution of sodium nitroprusside in aqueous ammonia. Some proteins test positive when denatured, indicating that thiol groups are liberated. [62] [63] [64]
Sodium nitroprusside is used in a separate urinalysis test known as the cyanide nitroprusside test or Brand's test. In this test, sodium cyanide is added first to urine and let stand for about 10 minutes. In this time, disulfide bonds will be broken by the released cyanide. The destruction of disulfide bonds liberates cysteine from cystine as well as homocysteine from homocystine. Next, sodium nitroprusside is added to the solution and it reacts with the newly freed sulfhydryl groups. The test will turn a red/purple colour if the test is positive, indicating significant amounts of amino acids were in the urine (aminoaciduria). Cysteine, cystine, homocysteine, and homocystine all react when present in the urine when this test is performed. This test can indicate inborn errors of amino acid transporters such as cystinuria, which results from pathology in the transport of dibasic amino acids. [65]
Sodium nitroprusside is also used to detect amines, including those in illicit drugs. This compound is thus used as a stain to indicate amines in thin layer chromatography. [66] Sodium nitroprusside is similarly used as a presumptive test for the presence of alkaloids (amine-containing natural products) common in illicit substances. [67] The test, called Simon's test, is performed by adding 1 volume of a solution of sodium nitroprusside and acetaldehyde in deionized water to a suspected drug, followed by the addition of 2 volumes of an aqueous sodium carbonate solution. The test turns blue for some secondary amines. The most common secondary amines encountered in forensic chemistry include 3,4-methylenedioxymethamphetamine (MDMA, the main component in ecstasy) and phenethylamines such as methamphetamine. Sodium nitroprusside is also useful in the identification the mercaptans (thiol groups) in the nitroprusside reaction.
Sodium nitroprusside is primarily used as a vasodilator. It was first used in human medicine in 1928. [8] By 1955, data on its safety during short-term use in people with severe hypertension had become available. [8] Despite this, due to difficulties in its chemical preparation, it was not finally approved by the US FDA until 1974 for the treatment of severe hypertension. [8] By 1993, its popularity had grown such that total sales in the US had totalled US$2 million. [8]
In chemistry, cyanide is a chemical compound that contains a C≡N functional group. This group, known as the cyano group, consists of a carbon atom triple-bonded to a nitrogen atom.
Potassium hexacyanidoferrate(II) is the inorganic compound with formula K4[Fe(CN)6]·3H2O. It is the potassium salt of the coordination complex [Fe(CN)6]4−. This salt forms lemon-yellow monoclinic crystals.
Nitric oxide is a colorless gas with the formula NO. It is one of the principal oxides of nitrogen. Nitric oxide is a free radical: it has an unpaired electron, which is sometimes denoted by a dot in its chemical formula. Nitric oxide is also a heteronuclear diatomic molecule, a class of molecules whose study spawned early modern theories of chemical bonding.
In chemistry, azide is a linear, polyatomic anion with the formula N−3 and structure −N=N+=N−. It is the conjugate base of hydrazoic acid HN3. Organic azides are organic compounds with the formula RN3, containing the azide functional group. The dominant application of azides is as a propellant in air bags.
The nitrite ion has the chemical formula NO−
2. Nitrite is widely used throughout chemical and pharmaceutical industries. The nitrite anion is a pervasive intermediate in the nitrogen cycle in nature. The name nitrite also refers to organic compounds having the –ONO group, which are esters of nitrous acid.
Sodium nitrite is an inorganic compound with the chemical formula NaNO2. It is a white to slightly yellowish crystalline powder that is very soluble in water and is hygroscopic. From an industrial perspective, it is the most important nitrite salt. It is a precursor to a variety of organic compounds, such as pharmaceuticals, dyes, and pesticides, but it is probably best known as a food additive used in processed meats and in fish products.
Thiocyanates are salts containing the thiocyanate anion [SCN]−. [SCN]− is the conjugate base of thiocyanic acid. Common salts include the colourless salts potassium thiocyanate and sodium thiocyanate. Mercury(II) thiocyanate was formerly used in pyrotechnics.
The sodium fusion test, or Lassaigne's test, is used in elemental analysis for the qualitative determination of the presence of foreign elements, namely halogens, nitrogen, and sulfur, in an organic compound. It was developed by J. L. Lassaigne.
Nitrosation and nitrosylation are two names for the process of converting organic compounds or metal complexes into nitroso derivatives, i.e., compounds containing the R−NO functionality. The synonymy arises because the R-NO functionality can be interpreted two different ways, depending on the physico-chemical environment:
Copper(I) cyanide is an inorganic compound with the formula CuCN. This off-white solid occurs in two polymorphs; impure samples can be green due to the presence of Cu(II) impurities. The compound is useful as a catalyst, in electroplating copper, and as a reagent in the preparation of nitriles.
In organic chemistry, nitroso refers to a functional group in which the nitric oxide group is attached to an organic moiety. As such, various nitroso groups can be categorized as C-nitroso compounds, S-nitroso compounds, N-nitroso compounds, and O-nitroso compounds.
Gasotransmitters is a class of neurotransmitters. The molecules are distinguished from other bioactive endogenous gaseous signaling molecules based on a need to meet distinct characterization criteria. Currently, only nitric oxide, carbon monoxide, and hydrogen sulfide are accepted as gasotransmitters. According to in vitro models, gasotransmitters, like other gaseous signaling molecules, may bind to gasoreceptors and trigger signaling in the cells.
Metal nitrosyl complexes are complexes that contain nitric oxide, NO, bonded to a transition metal. Many kinds of nitrosyl complexes are known, which vary both in structure and coligand.
Nitrosyl chloride is the chemical compound with the formula NOCl. It is a yellow gas that is commonly encountered as a component of aqua regia, a mixture of 3 parts concentrated hydrochloric acid and 1 part of concentrated nitric acid. It is a strong electrophile and oxidizing agent. It is sometimes called Tilden's reagent, after William A. Tilden, who was the first to produce it as a pure compound.
Cyanide poisoning is poisoning that results from exposure to any of a number of forms of cyanide. Early symptoms include headache, dizziness, fast heart rate, shortness of breath, and vomiting. This phase may then be followed by seizures, slow heart rate, low blood pressure, loss of consciousness, and cardiac arrest. Onset of symptoms usually occurs within a few minutes. Some survivors have long-term neurological problems.
Roussin's red salt is the inorganic compound with the formula K2[Fe2S2(NO)4]. This metal nitrosyl was first described by Zacharie Roussin in 1858, making it one of the first synthetic iron-sulfur clusters.
A nitrovasodilator is a pharmaceutical agent that causes vasodilation by donation of nitric oxide (NO), and is mostly used for the treatment and prevention of angina pectoris.
Biological functions of nitric oxide are roles that nitric oxide plays within biology.
Cyanometallates or cyanometalates are a class of coordination compounds, most often consisting only of cyanide ligands. Most are anions. Cyanide is a highly basic and small ligand, hence it readily saturates the coordination sphere of metal ions. The resulting cyanometallate anions are often used as building blocks for more complex structures called coordination polymers, the best known example of which is Prussian blue, a common dyestuff.
In organometallic chemistry, transition metal complexes of nitrite describes families of coordination complexes containing one or more nitrite ligands. Although the synthetic derivatives are only of scholarly interest, metal-nitrite complexes occur in several enzymes that participate in the nitrogen cycle.