Fast-dissolving preparations

The serum levels of digoxin may be reduced by about one-third if metoclopramide is given with slowly dissolving forms of digoxin. No interaction is likely with digoxin in liquid form or in fast-dissolving preparations. 

Table 1.5 Novel preparations for improving bioavailability of drugs Oral drug delivery Fast-dissolving tablets...

Matrix mini-tablets based on starch/microcellulose wax mixtures have been described (31,32). The possibility with these and other mini-tablets is that different dose levels can be administered by changing the number of mini-tablets within a capsule for adults or using single units for children. It is also possible to utilize fast-dissolving mini-tablets to prepare liquid dosages extemporaneously. 

Effervescent preparations, powders and granules, chewable dosage forms and fast-dissolving/disintegrating preparations in the oral cavity. 

Information is very limited, but the interaction seems to be established. It is not likely to occur with solid form, fast-dissolving digoxin preparations (e.g. liquid-filled capsules) or digoxin in liquid form, but only with those preparations which are slowly dissolving (i.e. some tablet formulations). A reduction in digoxin levels of one-third could result in under-digitalisation. There seems to be no information about digitoxin. 

Fibers possess several advantages in the preparation of fast-dissolving oral DDSs. First, they have an extraordinarily high surface area per unit mass. 

Normally hard capsules are swallowed whole, but when they need to be administered to infants, pharmacy-prepared capsules may be opened before administration and the contents mixed with a small amount of suitable liquid or soft food. However, solid dosage forms that provide flexible dosing, such as fast dissolving granules (sprinkles) and uncoated mini-tablets may be preferable for paediatric patients because taste and smell can be masked and therefore compliance may improve [3]. 

S. Jacob, A. Shirwaikar, A. Joseph, K. Srinivasan, Novel co-processed excipients of mannitol and microcrystalline cellulose for preparing fast dissolving tablets of ghpizide, Indian... 

H. Shimoda, K.Taniguchi, M. Nishimura, K. Matsuura, T. Tsukioka, et al.. Preparation of a fast dissolving oral thin film containing dexamethasone A possible application to antiemesis during cancer chemotherapy, European J. Pharm. Biopharm., 73 361-365, 2009. 

Preparation of the sulphones. Dissolve the 2 4-dinitrophenyl-sulphide in the minimum volume of warm glacial acetic acid and add 3 per cent, potassium permanganate solution with shaking as fast as decolourisation occurs. Use a 50 per cent, excess of potassium permanganate if the sulphide tends to precipitate, add more acetic acid. Just decolourise the solution with sulphur dioxide (or with sodium bisulphite or alcohol) and add 2-3 volumes of crushed ice. Filter off the sulphone, dry, and recrystaUise from alcohol. 

Printing Inks. Printing ink preparation is similar to many coating systems. The resin is dissolved in the solvent, followed by pigment dispersion to produce the ink. In most printing operations, the solvent must evaporate fast for best production speed. Alcohol—hydrocarbon solvent combinations are used with polyamide resins for some printing processes (see Inks). 

Fast Color Salts. In order to simplify the work of the dyer, diazonium salts, in the form of stable dry powders, were introduced under the name of fast color salts. When dissolved in water they react like ordinary diazo compounds. These diazonium salts, derived from amines, free from solubilizing groups, are prepared by the usual method and are salted out from the solutions as the sulfates, the metallic double salts, or the aromatic sulfonates. The isolated diazonium salt is sold in admixture with anhydrous salts such as sodium sulfate or magnesium sulfate. 

In some materials, semiconductors in particular, interstitial atoms play a crucial role in diffusion. Thus, Frank and Turnbull (1956) proposed that copper atoms dissolved in germanium are present both substitutionally (together with vacancies) and interstitially, and that the vacancies and interstitial copper atoms diffuse independently. Such diffusion can be very rapid, and this was exploited in preparing the famous micrograph of Figure 3.14 in the preceding chapter. Similarly, it is now recognised that transition metal atoms dissolved in silicon diffuse by a very fast, predominantly interstitial, mechanism (Weber 1988). 

Procedure. Prepare an indicator solution by dissolving 0.5 g of fast sulphon black F in 100 mL of de-ionised water. 

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