What Is Sodium Salicylate?
Sodium salicylate, with molecular formula C7H5NaO3 and molecular weight 160.10, is a compound of salicylic acid with a sodium salt, and is a white crystal or crystalline powder at room temperature. It is extremely soluble in water, soluble in acetic acid (100), and slightly soluble in ethanol (95).
It is characterized by gradual coloration by light, and thus by sunlight and air, and especially by exposure to ammonia gas.
Industrially, it is obtained by synthesizing sodium phenoxide and carbon dioxide at high temperatures and pressures. Also called sodium salicylate, it is decomposed by heating to produce oxygen dioxide.
Uses of Sodium Salicylate
Sodium salicylate has long been used in medicine for its anti-inflammatory and analgesic properties. It is particularly applicable to symptomatic neuralgia (nerve pain with an obvious cause, such as trauma, pressure, inflammation, or infection) that tends to occur in limbs and joints.
It is also used as a denaturant and preservative in cosmetics. In the case of cosmetics, the amount of sodium salicylate that can be contained is small, so it is not a major problem.
However, those with a history of hypersensitivity to salicylic acid compounds (such as aspirin) may experience flare-ups of allergic symptoms such as asthma. It may also aggravate symptoms in patients with ulcerative colitis and Crohn’s disease.
In animal studies, teratogenic effects and weak ductus arteriosus contraction in fetuses have been reported, so pregnant women are advised to reduce the dosage due to the possibility of fetal effects.
Miscibility With Other Drugs
Sodium salicylate liberates salicylic acid in acidic solutions and precipitates with iron salts in neutral solutions, forming insoluble iron salicylate. It may also precipitate with alkaloid salts as insoluble salicylate alkaloid salts.
Discoloration occurs when mixed with alkalis, iron salts, and nitrites. Alkali bicarbonate turns reddish brown, and iron salts turn purple. The discoloration caused by iron salts does not change the therapeutic effect.
In aqueous solution, the alkali may cause photo-oxidation, resulting in coloration or precipitation, but this reaction is catalyzed by copper, iron, and manganese, and can be prevented by adding hydrogen sulfite or thiosulfate to the mixture.
Uses in the Medical Field
Sodium salicylate is thought to exert its analgesic and anti-inflammatory effects by inhibiting cyclooxygenase and decreasing the synthesis of prostaglandins and thromboxane precursors from arachidonic acid, but this remains unclear. Unlike aspirin, however, it does not inhibit platelet aggregation.
The exact mechanism of action of its anti-inflammatory and analgesic effects is unknown. It is thought to exert its effects by inhibiting the synthesis of prostaglandins or other factors in inflammatory tissues, thereby blocking the generation of nerve impulses.