Definition and properties
An effervescent tablet is an uncoated tablet that is dissolved or allowed to disintegrate in water before administration. The resulting solution or suspension is drunk or, less commonly, used in other ways. For example, effervescent tablets exist for cleaning dentures or cold remedies with essential oil for inhalation. Effervescent tablets are usually prepared with sufficiently cold – not tempered – tap water. However, some medications are also administered as a hot drink. The solution may be additionally stirred with a spoon before consumption. Effervescent tablets should not be taken without prior preparation.
Chemical Basics
Effervescent tablets contain a base such as a carbonate or hydrogen carbonate (e.g., sodium hydrogen carbonate) as an excipient on the one hand. On the other hand, they contain an organic acid such as citric acid, vitamin C or tartaric acid. When these two substances come into contact with water, the gas carbon dioxide is formed, which causes the tablet to dissolve. The pharmacopoeia requires that the disintegration must have occurred within five minutes.
- Sodium hydrogen carbonate (NaHCO3) + acid (H+) sodium (Na+) + water (H2O) + carbon dioxide (CO2, gaseous)
Effervescent tablets contain other excipients such as sweeteners, binders, lubricants, preservatives and dyes. They are much larger than ordinary tablets because they are not swallowed directly.
Advantages
One advantage of this dosage form is that the active ingredients are already dissolved. This may allow a faster onset of action, which is desirable in pain management, for example. This has been shown for paracetamol, for example. Effervescent tablets are also suitable for patients with swallowing difficulties and for children. They may also be better tolerated by the stomach.
Disadvantages
They are more cumbersome and less discreet to take because a glass or cup of water is needed and the tablet must be dissolved. Effervescent tablets must be made and stored away from moisture. They are specially packaged so that they do not become damp and the reaction begins too soon. They are often sold in tubes that contain a desiccant in the lid. They may also be wrapped in foil or individually blister packaged. Effervescent tablets are more fragile than ordinary tablets and can break quickly. The taste of the active ingredients can be a problem for the formulation.
Divisibility
Some effervescent tablets have a breaking groove and can be divided. If they do not have one, two unequal halves may result. The remaining half has a limited shelf life of a few days in the blister according to the SmPC.
Examples
Some examples of active ingredients formulated as effervescent tablets:
