Effervescent stability

Uses. Commercial monocalcium phosphate is available as both the anhydrous and the monohydrate salts. Most uses are based on acidic properties. Monocalcium phosphate is used to control acidity in powdered drink mixes, as an ingredient in effervescent tablets, as a plastics stabilizer, and in ceramics. Its single largest appHcation is as a leavening agent in bread, cake mixes, and self-rising flour. 

Figure 9. Stabilizing effect of methylcellulose on foams generated by a suspension of effervescent antacid granules containing magnesium trisilicate and aluminum hydroxide...

Figure 9 illustrates the stabilizing effect of methylcellulose on the foams generated by a suspension of effervescent antacid granules containing magnesium trisilicate and ammonium hydroxide. Samples 1 and 2 are identical, except for 0.01% of methylcellulose contained in sample 1. The foam in sample 1 (methylcellulose) is stable even after 5 minutes, while the sample without methylcellulose has virtually no foam after 30 seconds. 

Stability of Lead Carbonate, (a) To a neutral lead nitrate solution add Na2CC>3 solution drop by drop, noting the white precipitate and the absence of effervescence. 

Shortly after the discovery of this reaction, a number of observers questioned whether radicals were intermediates or whether the reaction proceeded by purely cationic chemistry by the aryl cation mechanism (Scheme 2). If this were the case, then the formation of products such as the alcohols 4 would proceed equally well in the absence of TTF. The vigor of the effervescence seen immediately on addition of TTF, together with the long-term stability of solutions of the diazonium salts in solution in moist acetone and other solvents in the absence of TTF, immediately disproves this, but additional experiments were performed to show the special character of TTF in the reactions. 

The greatest problem with effervescent products is the loss of reactivity with time if exposed prematurely to moisture (i.e., the stability of the effervescent system). In addition, the stability of the drug and some excipients, such as flavors, also must be considered. 

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. ... 

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. 

The effect of environmental moisture on the physical stability of effervescent tablets in foil-laminate packages containing microscopic imperfections was examined. Physical stability, after storing at different RH and temperature conditions, was assessed by noting whether the tablet components reacted prematurely. 

Anderson, N.R. Banker, G.S. Peck, G.E. Quantitative evaluation of pharmaceutical effervescent systems II stability monitoring by reactivity and porosity measurements. J. Pharm. Sci. 1982, 71, 7-13. 

The stability and shelf-life of effervescent powders are essentially assured by protection against external moisture. Single-dose sachets are manufactured with suitable complexes to prevent premature reaction caused by external moisture or excess internal moisture from the granulation process. Special stability studies under different conditions are required for these powders. The dissolution time must be less than 3 min this is an index of stability. 

Vitamins are very often incorporated in effervescent granules. Table 76 gives details of a multivitamin effervescent granule formulation developed in the laboratory. The chemical stability of this guide formulation has not yet been tested. 

Table 147 gives a guide formulation developed in the laboratory for effervescent tablets for children, containing 1 g of micronized crospovidone as the active ingredient. No problems are to be expected with the chemical stability of this formulation. However, moisture-proof packaging is recommended, to stabilize the physical properties of the tablets for the duration of their intended shelf-life. 

To overcome insufficient stability in liquid state, dispersible tablets and effervescent dosage forms provide a dry alternative to liquid but are not without inherent issues (large volume of diluent, bicarbonate ingestion, sodium and/or potassium content not suitable for renally impaired patients, difficult taste masking). 

M. Iijima, T. Hakata, S. Kimura, T. Okabe, Y. Uchino, H. Sato, K. Sugibayashi, and Y. Morimoto, Stability evaluation of effervescent suppositories [in Japanese], Yakuzaigaku 53, 102-108(1993). 

Multivitamin Effervescent Tablets, WG 4. Chemical and physical stability (20-25 °C)... 

The fact that the phenomenon of effervescence may be exacerbated due to a large number of microcavities in tartrate microcrystals is an additional reason for ensuring the thorough tartrate stabilization of still wine intended for sparkling wine production. Treatment parameters at this stage must take into account the destabilizing... 

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. 

Gas bubbles are relevant to various aspects of the atomization and sprays. In flashing process or flash atomization, bubbles are formed inside the liquid which significantly alter the atomization process (see Chap. 10). Also in effervescent atomizers, high-pressure air is injected inside a liquid and disperses as small bubbles. In addition, bubbles are formed in cavitating nozzles, which significantly alter the atomization process. Gas bubbles go through volume oscillations in addition to shape oscillation discussed in the previous section. In this section, dynamic evolution and stability of a spherical bubble undergoing volume oscillation is discussed. 

The successful operation of effervescent atomizers has been dependent on the ability to maintain a stable uniform sized bubble flow. Bubbly flows depend on nozzle geometry, air and liquid flow rates, and they become influenced by pressure and velocity instabilities. The stability of bubbly flows depends upon two factors (1) bubble coalescence and (2) characteristics of the bubble formation, which may affect their coalescence. The bubble formation may occur at various regimes, which... 

There are also few numerical and theoretical studies on the effect of various parameters on the effervescent spray characteristics. Neglecting the secondary atomization and following a stability analysis, Lund et al. [36] obtained the following theoretical correlation for the spray SMD... 

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