Thiols and cysteine
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.Sodium nitroprusside is used in a separate urinalysis test known as the cyanide nitroprusside test or Brands 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. Amines
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. Sodium nitroprusside is similarly used as a presumptive test for the presence of alkaloids (amine-containing natural products) common in illicit substances.
Sodium nitroprusside (SNP), sold under the brand name Nitropress among others, is a medication used to lower blood pressure. 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. It is used by continuous injection into a vein. Onset is nearly immediate and effects last for up to ten minutes. It has been known to cause reflex tachycardia. It is often used as the vasodilator of choice in acute, emergency situations. The pharmacological activation is in relation to the release of nitric oxide which occurs from sodium nitroprusside which serves to activate Sodium Guanylyl Cyclase. Common side effects include low blood pressure and cyanide toxicity. Other serious side effects include methemoglobinemia. It is not generally recommended during pregnancy due to concerns of side effects. High doses are not recommended for more than ten minutes. It works by increasing nitric oxide levels in the blood, which increases cGMP levels in cells, and causes dilation of blood vessels.Sodium nitroprusside was discovered as early as 1850 and found to be useful in medicine in 1928. It is on the World Health Organizations List of Essential Medicines. Sodium nitroprusside is light sensitive, so it needs to be shielded from light to prevent degradation. Medical use
Sodium nitroprusside is intravenously infused in cases of acute hypertensive crises. Its effects are usually seen within a few minutes.Nitric oxide reduces both total peripheral resistance and venous return, thus decreasing both preload and afterload.