Effervescent products tableting

With regard to compressibility and compactibility, the considerations pertaining to raw materials in effervescent products are similar to the ones that prevail in evaluating raw materials intended for conventional tablets. However, poor compactibility cannot usually be compensated for by the use of binders, as this will prevent a rapid dissolution of the effervescent tablet. Addition of a binder is generally not as critical for the dissolution of effervescent granules or powders. 

A very important property for effervescent products is the adsorption/desorption isotherm of the raw material and, consequently, its moisture content. To avoid a premature effervescent reaction in the tablets. 

Conventional processing equipment (mixers, granulators, roller compactors, drying equipment, and mills) can be used to produce effervescent preparations if the influence of atmospheric moisture is considered. As a rule, tablet presses have to be adapted to handle effervescent products, except for tablets with a sufficient proportion of a self-lubricating substance, such as acetylsalicylic acid. 

Some effervescent tablet products are successfully produced by direct compression (e.g., acetylsalicylic acid products). Direct compression normally requires careful selection of raw materials to achieve a free-flowing, non-segregating, compressible mixture. Effervescent products present the same problems as conventional products in direct compression. 

Effervescent tablets were produced using four different formulations that contained citric and/or tartaric acid and NaHCOs with polyvidone and PEG 6000. The adhesion of each formulation to the metal faces of the punch tips was determined by means of electron microscopy, surface-roughness measurements, and quantification of punch-weight variations during tablet production. The basic formulations were inherently adhesive and produced tablets with a weak, porous structure the tablets were rougher than conventional, non-effervescent compressed tablets. Both formulations that contained tartaric acid produced tablets with a lower surface roughness and had less... 

Both chemical and physical properties have to be considered when evaluating effervescent products. In this review, only the physical properties will be discussed, except where the chemical characteristics are especially influenced by the effervescent base. For more detail, Ph. Eur. includes a special disintegration test for effervescent tablets and granules. ... 

The disintegration and dissolution times are very important characteristics of effervescent products. A well-formulated effervescent tablet will disintegrate and dissolve within 1-2 min to form a clear solution. Consequently, the residue of undissolved drug must be minimal. The temperature of the water influences the dissolution time. It is, therefore, important to choose a water temperature that is actually used by consumers (e.g., cold tap water). Ph. Eur. includes a general requirement on disintegration time of 5 min in water 15-25°C.t ... 

Even the moisture in the air may be enough to initiate the effervescent reaction of an effervescent product if it is not properly protected. When the consumer opens the container, the effervescent product will again be exposed to the moisture in the air. Consequently, the packaging of all effervescent products is very important. The time between tablet production and start of packaging operation should be kept as short as possible. 

Effervescent products are usually packed in individual aluminum foil pouches and effervescent tablets are often packed in metal tubes. To avoid excessive laminate stress, the dimensions of the sachets should be adapted to the dimensions of the tablet or the amount of granulate. These pouches are arranged in conveniently sized strips and stacked in a paperboard box. 

The commercial manufacturing of effervescent products involves controlling air humidity in the production area. Special tablet machines are generally required, and the package is a very important part of the effervescent product. Over-the-counter analgesics have been very successful as effervescent tablets on certain markets. 

Chemical stability, disintegration rate, dissolution profile, friability, and hardness are the major stability attributes for the tablet dosage form. An unoptimized tablet formulation may become soft or very hard after storage, with altered dissolution profiles, and as a result, its dissolution profile and bioavailability may not be appropriate. If effervescent products are not properly formulated, manufactured, and packaged, the premature acid-base reaction will cause the product s self-destruction. 

Spray-dried particles have also been incorporated into effervescent products. In one study, spray drying was used to protect a degradation-sensitive active by coating fine particles of the drug with a sugar alcohol solution (50). In vivo results of tablets made using the spray-dried particles combined with coated citric add and sodium bicarbonate revealed that the active was rapidly absorbed from the tablet. 

The criteria to choose the raw materials for effervescent products are not very different from those for conventional tablets, since in both cases good compressibility and compactability are the targets to be achieved. 

Effervescent Tablets. Effervescent tablets are another means of supplying medications to the elderly. This type of formulation provides the patient with an easy-to-swallow product that is aesthetically pleasing (i.e., forms a clear solution, rather than a cloudy... 

Effervescence these systems that consist for instance of a carbonate or bicarbonate salt and an organic acid like e.g. citric acid, develop carbon dioxide gas on contact with water and are well known in pharmaceutical/health food tablets. A few market products exist that make use of this system but for reasons explained above this system is not that suitable for detergent tablets with a high content of surfactants. 

Sales of Ca supplements alone were 875 million in the United States in 2002, and comprised 60% of all mineral supplement sales (Anonymous, 2004). In 2004, sales of Ca supplements increased by 9.3% (Uhland et ah, 2004), possibly to some extent in response to the Surgeon General s report on bone health that was issued that year. More recently in 2006, it was projected that dietary supplement sales in the United States would approach 5 billion (Anonymous, 2006). While Ca derived from a balanced diet is preferable, Ca supplements are a popular noncaloric alternative for increasing daily Ca intake. There are a vast number of oral Ca supplements available in the market place in the form of capsules, tablets, chewable tablets, effervescent tablets, liquids, powders, suspensions, wafers, and granules. However, not all Ca salts are equally soluble or bioavailable and the dose of Ca on the label of a supplement may not necessarily be reflective of the relative amount of available Ca once consumed. Furthermore, the same Ca salt may be more or less bioavailable depending on the production process and materials used to manufacture the supplement. 

Tablet disruption following production of carbon dioxide is another mechanism used to enhance disintegration. This uses a mixture of sodium bicarbonate and a weak acid such as citric acid or tartaric acid and is exploited for effervescent formulations.

Effervescent tablets normally have a high sodium content. In most of the effervescent analgesic products... 

The stability of three commercial effervescent and one dispersible aspirin tablet were evaluated by factorially designed experiments. Temperature affected the hydrolysis of all tablets, whereas humidity influenced one product in a plastic tube and one in an aluminum tube. ... 

Effervescent tablets are normally produced by machines with external lubrication systems. Most tablet machine manufacturers can add this type of equipment to their rotary machines. Products with a high proportion of acetylsalicylic acid can be manufactured without any traditional lubricants. Consequently, conventional rotary tablet presses can be used. Effervescent acetylsalicylic acid tablets are produced on ordinary high-speed rotary presses at the Pharmacia plant in Helsingborg, Sweden. 

As the mass of an effervescent tablet is, as a rule, many times larger than that of a conventional tablet, larger amoimts of raw material will have to be handled when packaging the same number of tablets. Therefore, the production area will be larger, too, unless a compact continuous line has been constructed. 

The metal tube is a multiple-use container sealed with a moisture-proof closure. The tablets are stacked on top of one another. Consequently, a minimum of air surrounds them. The tubes are seamless, extruded aluminum packages. They are closed by tightly fitting plastic snap caps that contain a desiccant chamber. Tubes of plastic materials, such as polyvinyl chloride or polypropene, have been tested with effervescent tablets. Acceptable stability was obtained with some of these products. Plastic tubes are used more often due to their lower cost and lower noise level during the packaging operation. 

Citric acid (as either the monohydrate or anhydrous material) is widely used in pharmaceutical formulations and food products, primarily to adjust the pH of solutions. It has also been used experimentally to adjust the pH of tablet matrices in enteric-coated formulations for colon-specific drug delivery. Citric acid monohydrate is used in the preparation of effervescent granules, while anhydrous citric acid is widely used in the preparation of effervescent tablets.Citric acid has also been... 

As an excipient, potassium bicarbonate is generally used in formulations as a source of carbon dioxide in effervescent preparations, at concentrations of 25-50% w/w. It is of particular use in formulations where sodium bicarbonate is unsuitable, for example, when the presence of sodium ions in a formulation needs to be limited or is undesirable. Potassium bicarbonate is often formulated with citric acid or tartaric acid in effervescent tablets or granules on contact with water, carbon dioxide is released through chemical reaction, and the product disintegrates. On occasion, the presence of potassium bicarbonate alone may be sufficient in tablet formulations, as reaction with gastric acid can be sufficient to cause effervescence and product disintegration. 

---