Tablet coats films

Okhamafe, A.O. York, P. Relationship between stress, interaction and the mechanical properties of some pigmented tablet coating films. Drug Dev. Ind. Pharm. 1985, 11 (1), 131-146. 

In a four-part article, Porter [130] provided a comprehensive review of tablet coating technology, with emphasis on contemporary practice. More specifically, a recent review [131] discusses characterization techniques for the aqueous film coating process and provides a useful influence matrix between process variables and final product attributes. 

In some instances there is a possibility that the efficacy of these preparations may be compromised by conditions associated with the digestive tract. Most function at pH values approaching neutrality. They would thus display activity possibly in saliva and particularly in the small intestine. However, the acidic conditions of the stomach (where the pH can be below 1.5) may denature some of these enzymes. Furthermore, the ingested enzymes would also be exposed to endogenous proteolytic activities associated with the stomach and small intestine. Some of these difficulties, however, may be at least partially overcome by formulating the product as a tablet coated with an acid-resistant film to protect the enzyme as it passes through the stomach. 

Tablets coated with the Eudragit-PEG 400 mixture were made with three different polymer film thicknesses 6, 10 and 15 mg (KET-R, 10 and 15 tablets). For these tablets it was not possible to obtain swelling measurements because this was prevented by the lake coating.

The inherent complexities of this process are well illustrated by the process operational boundaries highlighted in Figure 3. Although this diagram specifically references tablet coating in a side-vented pan, the concepts are applicable to the film coating of all types of products in a wide variety of coating machines. 

Tablet coating can occur by different techniques (e.g., sugar, film, or compression). Film coating has been the most common technique over recent years and will be the focus of this section.

Polyvinyl actetate phthalate (FVAPa). This is used often at concentrations of 9 to 10 percent for tablet enteric film coating. Insoluble in buffer solutions below pH 5 and soluble at pH values above 5, it shows a sharp solubility response with pH at 4.5 to 5. In addition to environmental pH, its solubility also can be influenced by ionic strength. 

Numerous formulation are available for all film-forming polymers offered in the market. Thus, it is possible to dispense with many of the preliminary tests and concentrate development work on the special problems of the formulation in question. In this chapter, we will focus on SEPIFILM and Kollidon VA 64. Table 16 presents proven basic formulations reported on in the literature [61] and polymers used for the most important commercially available film formers, which also can be used as a basis for further tablet coating. 

FIGURE 31 (a) Tablet coated with HPMC smooth film, medium discontinuity between film and core. (b) Tablet coated with SEPIFILM 752 white clear edge perfectly coated, good adhesion of film to core and continuity between film and core. 

Hess, H., and Janssen, H. J. (1969), Lacquered tablets and film coated tablets, Pharm. Acta Helv., 44, 581. 

Contents. Note the total number of tablets or other preparation in the container, together with an estimate of the total number which the container could hold if filled. Note the shape (flat, bevelled, biconvex, etc.), whether compression-coated, film-coated, enteric-coated, or sugar-coated, markings (numbers, letters, symbols, or score marks), exterior and interior colour, layered and core tablets, and mean weight, diameter, and thickness. 

Investigations, related to the photoprotection of nifedipine tablets using films containing titanium dioxide and/or tartrazine, revealed that the photoprotective effect of a film could be evaluated by using its concentration of colorant (C) and thickness (L) value. This value is the product of concentration of the colorant C and the film thickness L. Tablets coated with films having the same CL value had the same photodegradation rates. Degradation rates were found to be proportional to the CL value for every colorant system tested (18). 

Another example, which demonstrates the importance of the spectral overlay principle, is the fact that film coatings containing titanium dioxide provide sufficient protection for molsidomine (Thoma K, Aman W. In preparation) (4), whereas nifedipine tablets coated with such films still show photodegradation (19). 

Zeneca Pharmaceuticals Tablets Parenterals Film coatings Formulogic... 

Most of the samples being investigated by SEM in the field of pharmaceutical technology are powders prepared by different methods, granules, pellets, tablets, and films from coated tablets. The sample preparation of bulk materials includes the following steps ... 

Tablet-coating processes are commonly used in the pharmaceutical industry. Aqueous film coatings composed of cellulose derivatives and other polymers are useful for the control of dissolution of drug from the tablet. Gravimetric analysis and HPLC are often used to determine the endpoint of the coating process.

Copovidone is included in the FDA Inactive Ingredients Guide (oral tablets, oral film-coated tablets, sustained action). 

In tableting, polydextrose solutions are used as binders in wet-granulation processes. Polydextrose is also used in the manufacture of directly compressible tableting excipients. Polydextrose solutions may also be used, in conjunction with other materials, as a film and tablet coating agent. 

Stearic acid has been reported to cause pitting in the film coating of tablets coated using an aqueous film-coating technique the pitting was found to be a function of the melting point of the stearic acid. ... 

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