Sodium Bicarbonate

Category

Alkalizing Agents; therapeutic AgentsAcid-Base regulator; Effervescent Disintegrant; Buffer (in solution); Freeze-drying Stabilizer; Gas forming Agents

Molecular Formula

NaHCO3

Molecular Weight

84.01

Grade

Pharmceutical Excipients

Description

Sodium bicarbonate occurs as an odorless, white, crystalline powder with a saline, slightly alkaline taste. The crystal structure is monoclinic prisms. Grades with different particle sizes, from a fine powder to free-flowing uniform granules, are commercially available.

UNII

8MDF5V39QO

Chemical Name

Carbonic acid monosodium salt

CAS Number

144-55-8

Synonyms

Baking soda; E500; Effer-Soda; monosodium carbonate; natrii hydrogenocarbonas; Sal de Vichy; sodium acid carbonate; sodium hydrogen carbonate

Administration route

Injections; ophthalmic; oral

Dosage Form

Injections; ophthalmic preparations; oral capsules, solutions, and tablets

Stability and Storage Conditions

When heated to about 50℃, sodium bicarbonate begins to dissociate into carbon dioxide, sodium carbonate, and water; on heating to 250-300℃, for a short time, sodium bicarbonate is completely converted into anhydrous sodium carbonate.

Source and Preparation

Sodium bicarbonate is manufactured either by passing carbon dioxide into a cold saturated solution of sodium carbonate, or by the ammonia-soda (Solvay) process, in which first ammonia and then carbon dioxide is passed into a sodium chloride solution to precipitate sodium bicarbonate while the more soluble ammonium chloride remains in solution.

Applications

Sodium bicarbonate is generally used in pharmaceutical formulations as a source of carbon dioxide in effervescent tablets and granules. It is also widely used to produce or maintain an alkaline pH in a preparation.

Safety

Sodium bicarbonate is used in a number of pharmaceutical formulations including injections and ophthalmic, otic, topical, and oral preparations. Sodium bicarbonate is metabolized to the sodium cation, which is eliminated from the body by renal excretion, and the bicarbonate anion, which becomes part of the body’s bicarbonate store. Any carbon dioxide formed is eliminated via the lungs. Administration of excessive amounts of sodium bicarbonate may thus disturb the body’s electrolyte balance, leading to metabolic alkalosis or possibly sodium overload with potentially serious consequences. The amount of sodium present in antacids and effervescent formulations has been sufficient to exacerbate chronic heart failure, especially in elderly patients. Orally ingested sodium bicarbonate neutralizes gastric acid with the evolution of carbon dioxide and may cause stomach cramps and flatulence.When used as an excipient, sodium bicarbonate is generally regarded as an essentially nontoxic and nonirritant material. LD50 (mouse, oral): 3.36 g/kg LD50 (rat, oral): 4.22 g/kg

Incompatibilities

Sodium bicarbonate reacts with acids, acidic salts, and many alkaloidal salts, with the evolution of carbon dioxide. Sodium bicarbonate can also intensify the darkening of salicylates.In powder mixtures, atmospheric moisture or water of crystallization from another ingredient is sufficient for sodium bicarbonate to react with compounds such as boric acid or alum. In liquid mixtures containing bismuth subnitrate, sodium bicarbonate reacts with the acid formed by hydrolysis of the bismuth salt. In solution, sodium bicarbonate has been reported to be incompatible with many drug substances such as ciprofloxacin, amiodarone, nicardipine, and levofloxacin.