Effervescent tablet
Effervescent tablet is a tablet intended to be dissolved or dispersed in water before administration.
It generally contains in addition to active ingredients, mixture of acids/acid salts and carbonate and hydrogen carbonates which release
carbon dioxide when mixed with water. Occasionally, active ingredient itself could act as the
acid or alkali metal compound necessary for effervescent reaction.
Effervescent tablets are uncoated
tablets that generally contain acid substances and carbonates or bicarbonates and which react rapidly in the presence of water by releasing carbon dioxide. They are intended to be dissolved or dispersed in water before use.
Effervescent mixtures have been known for over 250 years. The famous Rochelle salt (potassium sodium tartrate) dates back to 1731 in conjunction with such a mixture. In the 18th century, effervescent powders as saline cathartics were listed as “Seidlitz powders” in the official compendia.
In the 1930s, the effervescent products gained much importance with the technology of Alka Seltzer. These mixtures have been moderately popular over the years since along with medicinal activity they are attractive dosage form for the patients. Effervescent reactions have been used alternatively preparation of other dosage forms, such as suppositories (for
laxative effect), vaginal
suppositories (for contraceptive effect) and drug delivery system (floating system and orally disintegrating tablets) (1).
Effervescent tablet
Effervescence has also proved its utility as an oral drug delivery system in the pharmaceutical and dietary industries for decades. In Europe, effervescent dosage forms are widespread, and their use is growing in the US because they offer pharmaceutical and nutraceutical companies a way to extend their market share.
A wide range of effervescent tablets have been formulated over the years. These include dental compositions containing
enzymes, contact lens cleaners, washing powder compositions, beverage sweetening tablets, chewable dentifrice, dental cleansers, surgical instrument sterilizers,
analgesics and effervescent candies as well as many preparations of prescription pharmaceuticals such as antibiotics, ergotamines,
digoxin,
methadone and L- dopa. Preparations for veterinary use have also been developed.
Soluble effervescent tablets are prepared by
compression. In addition to active ingredients, they contain mixtures of acids and carbonates like sodium, potassium bicarbonate that release carbon dioxide when dissolved in water.
Storage: Effervescent products should be stored in tightly closed containers or moisture proof packs. They should be preserved in air tight containers and protected from excessive moisture. Desiccants are usually added to the containers.
The Effervescent Reaction
Effervescence is the evolution of gas bubbles from a
liquid, as the result of a chemical reaction. The most common reaction for pharmaceutical purpose is the acid base reaction between
sodium bicarbonate and
citric acid.
Acid-base reactions between alkali metal bicarbonates and citric or tartaric acid have been used for many years to produce pharmaceutical preparations that effervesce as soon as water is added.
This reaction starts in presence of water, even with small amount as catalyzing agent, and because
water is one of the reaction products, it will accelerate the rate of reaction, leading to difficulty in stopping the reaction. For this reason, the whole manufacturing and storage of effervescent products is planned by minimizing the contact with water. In such systems, it is practically impossible to achieve much more than an atmospheric saturation of the solution with respect to released CO2. The physical and chemical basis of the formulation depends on essentially the total dissolution of bicarbonate salts and the acids prior to formation of free acids.
Active Ingredients
There are several categories of active ingredients, which would be advantageous if formulated as effervescent tablet.
- Drugs difficult to digest or disruptive to the stomach : calcium carbonate tablets per example
- pH-sensitive drugs such as amino acids and antibiotics
- Drugs requiring a large dose: A typical effervescent tablet can include more than 2 g of water-soluble active ingredients in a single dose.
Effervescent delivery can be used in the following treatments:
- Arthritis, inflammation and pain management
- Ulcers and gastrointestinal
- Allergies
- Osteoporosis
Drugs and drug compositions used as effervescent products
- Acetylsalicylic acid (Aspirin)
- Paracetamol (Acetaminophen)
- Ibuprofen
- Antacid preparations
- Ascorbic acid and other Vitamins
- Calcium
- Acetylcysteine, a mycolytic agent used as an antidote for paracetamol overdosage.
- Activated charcoal preparations used in the management of theophylline poisoning
Advantages Of Effervescent Tablets (4,5,6)
- Fast onset of action : the absorption is faster and more complete than with conventional tablet. Faster absorption means faster onset of action
- No need to swallow tablets
- Good stomach and intestinal tolerance
- More portability : more easily transported than liquid medication
- Improved palatability The effervescent tablets essentially include flavorings so they taste much better than a mixture of a non-effervescent powder in water.
- Superior stability compared to liquid forms
- More consistent response : predictable and reproducible pharmacokinetic profiles are more consistent than tablets or capsules.
- Incorporation of large amounts of active ingredients
- Accurate dosing
- Improved therapeutic effect The effervescent components help in solubilization of poorly soluble
drugs.
- Other Considerations:
- Convenient and easy administration than other liquid medicines to administer
- Less chance of misuse
- Ability to combine multiple active ingredients, if therapeutically appropriate
- Innovative, yet less risky than unproven technology
