5. Disintegrants/ Dissolution aids
Disintegration of effervescent tablets is enhanced by the carbon dioxide released during effervescence reaction. Common disintegrants used in conventional granules and tablets are not used in effervescent tablets because disintegrants are selected in such a manner that a clear solution should be obtained within five minutes after adding the tablet to a glass of water.
Effervescent formulations often contain sweeteners e.g., sorbitol, sucrose, aspartame or other natural sweeteners. Saccharin sodium can be used with sodium cyclamate in a 9:1 ratio. Water-soluble flavors may be added to mask unpleasant taste and make the product palatable.
Dyes or lake pigments may be included in the formulation to produce colored solutions or products. Color stability is also important and thus, colorants should be chosen as anhydrous material. Dried flower bud, herbs, chamomile extract may be used for this purpose.
These are added to effervescent formulations to increase wettability.
9. Antifoaming agents
In some cases, antifoaming agents (e.g. Polydimethylsiloxane) may be included in the formulation to reduce foam formation, and consequently, reduce the tendency of drugs to stick to the wall of the glass above the water level.
Note: The constituents of effervescent dosage forms or excipients used in the manufacture of effervescent tablets are required to have low moisture content and should be easily soluble.
Manufacture of effervescent tablets
The manufacture of effervescent dosage forms is similar in many ways to that of conventional granules or tablets, although due to the hygroscopicity and potential onset of the effervescence reaction in the presence of water, environmental control of relative humidity and water levels is of major importance during manufacture. A maximum of 25 % relative humidity or less is sufficient to avoid problems of atmospheric moisture. Moderate to cool temperatures (25 ºC) in the manufacturing areas are also essential to prevent the granulations or tablets from sticking to the machinery and from picking up moisture from the air, which may cause product instability.
Effervescent tablets are manufactured by both direct compression method and by compaction via granulation. In the latter case, traditional wet granulation is seldom used; instead, granules are formed by the fusion of particles as a result of their partial dissolution during wet massing of a moistened powder.
The equipment used in the manufacture of effervescent tablets are also the same as that for conventional tablets; the only difference is that it uses the rotatory press with special adaptations for compression.
Evaluation/ Quality Control of Effervescent tablets
The quality control parameters mentioned in pharmacopeias for the effervescent tablets are similar to those mentioned under conventional tablets. These include:
- Uniformity of Content
- Uniformity of Weight
- Disintegration time test
- Dissolution time test
Other parameters include:
- Thickness of tablets
- Crushing strength test
- Friability test
- pH of the solution
- Appearance of the tablets
- Determination of the carbon dioxide content (using gravimetric, colorimetric and volumetric methods)
- Water content (using the Karl Fischer’s method)
Read Also: Quality Control Tests for Tablets
Stability testing of effervescent tablets
Effervescent products are hygroscopic and unstable in the presence of moisture and as such premature exposure to moisture can lead to degradation or loss of reactivity. The elimination or inactivation of free water within the effervescent system is the key to stability, aside from manufacturing effervescent tablets in controlled environmental conditions.
After packaging, effervescent products are assessed by placing the product in a stability chamber set at 40 oC and 75 % relative humidity for at least 3 months. At the end of the 3 months, physical tests (package leak test, tablet appearance, disintegration time, tablet hardness, and sensory evaluation of the product) are performed to determine whether any off-notes developed during testing. Chemical assay of the active ingredient is also performed to determine if there has been any product degradation.
Read Also: Packaging of Effervescent Tablets
Examples of effervescent tablets
- Alka-Seltzer – Anhydrous citric acid, Aspirin, and Sodium bicarbonate (Bayer)
- Histac – Ranitidine HCl (Sun Pharma)
- Pepfiz-O&L – Papain, Fungal diastase and Simeticone (Sun Pharma)
- Effcal – CaCO3, Vitamin D3 (Sun Pharma)
- Tagamet – Cimetidine (Glaxo SmithKline)
- Zantac – Ranitidine (Glaxo SmithKline)
- Vitalmag – Magnesium citrate, Folic acid, Vitamin B6 (ICN Hungary)
- Calcium Sandoz – Calcium (ICN Hungary)
- Ca-C 1000 – Calcium, Ascorbic acid (ICN Hungary)
- Hangoverz – Aspirin, Caffeine (Pious Pharma. Ltd)
- Solpado – Paracetamol, Codeine phosphate (Sanofi-Aventis)
- Prolyte fizz – Glucose + Potassium Chloride + Sodium Bicarbonate + Sodium Chloride + Anhydrous Citric Acid (Cipla)
- Effer-K – Potassium citrate (Nomax Inc)
- Aspirin C – Acetylsalicylic acids (Bayer)
- Mohrle, R. (1989). Effervescent Tablets. In H. Lieberman, L. Lachman and J. Schwartz (Eds), Pharmaceutical Dosage Forms: Tablets, Volume 1 (pp.285-328), New York: Marcel Dekker, Inc.
- Ofoefule, S. I. (2002). Textbook of Pharmaceutical Technology and Industrial Pharmacy. Nigeria: Samakin (Nig) Enterprise.
- Patel, S. and Siddaiah, M. (2018). Formulation and Evaluation of Effervescent Tablets: A Review. Journal of Drug Delivery and Therapeutics, 8(6):296-303.
- Shayne, C. G. (2008). Pharmaceutical Manufacturing Handbook: Production and Processes. New Jersey: John Wiley & Sons, Inc.
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