Effervescent Excipients in Solid Dosage Forms
To make the effervescent reaction happening a carbonate component and an acid are required. In the presence of water, carbon dioxide is formed, and the tablet disintegrates. This leads to the typical bubbling. Effervescent tablets have a separate monograph in the pharmacopoeia which e.g., limits the disintegration time.
Typical Excipients
- Organic acids as citric, malic acid or others are used as acid component.
- The carbon dioxide-supplying components are usually sodium carbonates and sometimes potassium carbonate.
Disadvantages of Effervescent Tablets
Effervescent tablets are very sensitive to moisture. Not only during storage but also during manufacturing. Once the effervescent reaction has started, water is formed which drives the reaction forward. This is hardly stoppable. This means, both, storage and manufacturing need low humidity when both components are combined.
Granulation of Effervescent Formulations
When a granulation step for the effervescent formulation is necessary, a wet granulation must be performed separately, in two steps for the acid and for the carbonate component. A dry granulation ca be performed in one step with both components present, when keeping the relative humidity below 15%.
Other use of Effervescent Excipients
Sometimes, effervescent excipients are used as disintegrant in tablets or to support disintegration without having an effervescent tablet. The concentrations of both components is then much lower. This is only possible, when the API shows no pH sensitivity, to the acid or carbonate, respectively.
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Resource: Solids Development Consult
