Citric acid effervescent tablet formulations

Verain and coworkers (3) described the formulation of an effervescent paracetamol tablet dosed at 500 mg, containing saccharose and sorbitol as diluents. Other components were anhydrous citric acid, sodium or potassium bicarbonate, PVP, and sodium benzoate. The tablets were characterised by measurement of a number of responses, in particular the friability, the volume of carbon dioxide produced per tablet when it is put in water, and the time over which the tablet effervesced. The objective was to study the effects of 4 factors, the quantities of sorbitol and of citric acid per tablet, the nature of the bicarbonate (whether sodium or potassium bicarbonate), and the effect of different tableting forces on these responses. The... 

Tablet disruption following production of carbon dioxide is another mechanism used to enhance disintegration. This uses a mixture of sodium bicarbonate and a weak acid such as citric acid or tartaric acid and is exploited for effervescent formulations.

Lozenges These are compressed tablets formulated, without a disintegrant and must be allowed to dissolve in the mouth. They are used for local activity (throat lozenges) or for systemic effect (vitamins). Effervescent tablets These tablets undergo quick dissolution of actives in water due to internal liberation of carbon dioxide. By combining alkali metal carbonates or bicarbonates with tartaric or citric acid, carbon dioxide is liberated when placed in water. 

Effervescent tablets were produced using four different formulations that contained citric and/or tartaric acid and NaHCOs with polyvidone and PEG 6000. The adhesion of each formulation to the metal faces of the punch tips was determined by means of electron microscopy, surface-roughness measurements, and quantification of punch-weight variations during tablet production. The basic formulations were inherently adhesive and produced tablets with a weak, porous structure the tablets were rougher than conventional, non-effervescent compressed tablets. Both formulations that contained tartaric acid produced tablets with a lower surface roughness and had less... 

Citric acid (as either the monohydrate or anhydrous material) is widely used in pharmaceutical formulations and food products, primarily to adjust the pH of solutions. It has also been used experimentally to adjust the pH of tablet matrices in enteric-coated formulations for colon-specific drug delivery. Citric acid monohydrate is used in the preparation of effervescent granules, while anhydrous citric acid is widely used in the preparation of effervescent tablets.Citric acid has also been... 

Malic acid is used in pharmaceutical formulations as a general-purpose acidulant. It possesses a slight apple flavor and is used as a flavoring agent to mask bitter tastes and provide tartness. Malic acid is also used as an alternative to citric acid in effervescent powders, mouthwashes, and tooth-cleaning tablets. 

As an excipient, potassium bicarbonate is generally used in formulations as a source of carbon dioxide in effervescent preparations, at concentrations of 25-50% w/w. It is of particular use in formulations where sodium bicarbonate is unsuitable, for example, when the presence of sodium ions in a formulation needs to be limited or is undesirable. Potassium bicarbonate is often formulated with citric acid or tartaric acid in effervescent tablets or granules on contact with water, carbon dioxide is released through chemical reaction, and the product disintegrates. On occasion, the presence of potassium bicarbonate alone may be sufficient in tablet formulations, as reaction with gastric acid can be sufficient to cause effervescence and product disintegration. 

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