Effervescent tablets are becoming increasingly popular especially in the supplements and pharmaceutical sectors due to the ease in which they can be consumed.¹
According to the Therapeutic Goods Administration (TGA) who are the regulatory body for therapeutic goods in Australia, ‘effervescent’, in relation to a tablet, means an ‘uncoated tablet generally containing acid substances and carbonates or hydrogen carbonates which react rapidly in the presence of water to release carbon dioxide, and that is intended to be dissolved or dispersed in water before administration’.²
HOW IT WORKS
Let’s take a trip back to high school when our chemistry teacher introduced us to acids and bases. If you weren’t paying attention then, here’s the lowdown. The effervescence (‘fizz’) is a result of a simple acid-base reaction. When an acidic material (a pH below 7) and a basic material (a pH above 7) are placed together, they react to neutralise the acid and base properties, producing a salt (which has a neutral pH of around 7).
The most commonly used acid in effervescent formulations is citric acid due to its citrus-like taste, good water solubility as well it’s cost effectiveness.³ Other acids such as tartaric, malic, fumaric and adipic acids can also be used but can be expensive or have low water-solubility in comparison to citric acid.³
The most commonly preferred base source is sodium bicarbonate (AKA baking soda) due to its low cost, high solubility and intense reaction potential.³
So, when citric acid and sodium bicarbonate get together in water, carbon dioxide gas is released (causing the fizziness/bubbles). To initiate the reaction, water is important. If there is no water, acids or bases cannot dissociate and the reaction cannot start. Once water is present, the reaction begins, and more water is generated (see Figure 1).
THE BENEFITS WITH EFFERVESCENTS
1. Simple to use
Effervescents are a simple option for those who don’t like tablets or who have difficulty with swallowing tablets (dysphagia). Dysphagia is estimated to be prevalent in the community between 7 and 22% and its incidence is as much as 40 to 50% among older people in long-term care facilities.⁴
2. Pleasant tasting
Effervescent tablets also contain other ingredients such as flavours and sweeteners which help improve the taste. The addition of flavours and sweeteners can help to improve compliance and make taking medications an easier and more pleasant experience.
3. Gentle on the stomach
Studies have shown that when effervescents are dissolved in water, the pH of the final solution causes the drug to transit faster from the stomach to the small intestine thereby having the ability to reduce gastrointestinal irritation.¹ ⁵
In comparison, conventional tablets dissolve gradually in the stomach once ingested and can sometimes only partially dissolve which can occasionally cause gastrointestinal discomfort.¹ ⁵
4. Increases your water intake
It is recommended that women and men aged 19 years and older consumer 8-10 cups (2.1- 2.6 L) of water per day.⁶ As water is a requirement for effervescent tablets, this helps increase water intake, thereby helping to meet an individual’s daily water consumption.
5. Better bioavailability
Bioavailability refers to the extent and rate at which a drug is absorbed from its site of administration and reaches the systemic circulation (blood stream), in order to elicit its therapeutic effect in the target location within the body.
There have been several studies published which indicate that effervescent dosage forms are more bioavailable than conventional dose forms such as tablets and capsules.⁷ This is due to the fact that the carbon dioxide gas produced from the acid-base reaction increases their permeability.⁷⁻¹² Also, as effervescents enter the gastrointestinal system as a solution, results have indicated higher absorption rates within the body.⁸ ⁹
A 2018 study investigated the bioavailability of 500 mg of acetaminophen in tablet, capsule and effervescent forms.⁹ Results indicated that a quicker effect of absorption was observed in effervescent form in comparison to tablets and capsules.⁹
The bioavailability of a 200 mg ibuprofen effervescent tablet was compared against a sugar-coated tablet.10 Results indicated that the effervescent dose form allowed for faster bioavailability than the tablet whilst also helping to improve compliance with subjects who preferred the effervescent dose form due to difficulty in swallowing.¹⁰
A bioavailability study on a 500 mg of paracetamol with 2318 mg of sodium bicarbonate effervescent powder was compared against a coated tablet which determined that the effervescent powder dose form absorbed at least twice as fast compared to the tablet at 2 hours.¹¹
Finally, a bioavailability study of a 50 mg diclofenac effervescent tablet was investigated and compared with a sugar-coated diclofenac tablet.¹² Results indicated that the effervescent tablet showed rapid absorption without lag time in comparison to the conventional tablet.¹²
THE TAKE-AWAY
The properties of effervescent tablets are strongly influenced by factors such as the physical and chemical properties of the ingredients as well as the ratios of powders and the process parameters of tableting. Thus, a lot of work goes into formulating effervescent tablets to help ensure that it still retains the benefits of a conventional tablet (such as stability and accurate dosage) whilst also providing the added benefits of improved palatability, better bioavailability as well as ease of use.
