Solid dosage form

Water-soluble drugs present in a solid dosage form will dissolve in any moisture which has 

One of the main ways in which the excipients of the solid dosage form can affect the degradation of dmgs is by increasing the moismre content of the preparation. Excipients such as starch and povidone have particularly high water contents (povidone contains about 28% equilibrium moisture at 75% relative humidity). However, whether this high moismre 

Other studies on the influence of tablet excipients on dmg decomposition have identified problems with stearate salts and it has been suggested that these salts should be avoided as tablet lubricants if the active component is subject to hydroxide-ion-catalysed degradation. The degradative effect of the alkali stearates is inhibited in the presence of malic, hexamic or maleic acids owing, it is thought, to competition for the lubricant cation between the dmg and the additive acid. 

The base used in the formulation of suppositories can often affect the rate of decomposition of the active ingredients. Aspirin decomposes in several polyoxyethylene glycols which are often incorporated into suppository bases. Degradation was shown to be due in part to transesterification, giving the decomposition products salicylic acid and acetylated polyethylene glycol. The rate of decomposition, which followed pseudo first-order kinetics, was considerably greater than when a fatty base such as cocoa butter was used. Analysis of commercial batches of 100 mg indometacin-polyethylene glycol 

Excipients present in tablet formulations can have an impact on the photostability of the product, the effect arising in many cases from impurities present in the excipients. For example, free radical reactions involving 

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Bourquin J, Schmidli H, van Hoogevest P, Leuenberger H. Application of artificial neural networks (ANN) in the development of solid dosage forms. Pharm Dev Technol 1997 2 111-21. 

Many solid dosage forms made with green tea extracts can be seen in the market, and several are standardised to a content of polyphenols or catechins. 

Pharmaceutical Engineering Guides for New Facilities , 1998, Vol. 2, Oral Solid Dosage Forms, ISPE/FDA, February. 

Some antihistamines such as diphenhydramine, dimenhy-drinate, and meclizine are available without a prescription, making self-treatment convenient for patients. Antihistamines are available in a variety of dosage forms, including oral capsules, tablets and liquids. Liquid formulations are convenient for children or adults who are unable to swallow solid dosage forms. 

The most common extravascular route is oral. When a solution or a rapidly dissolving solid dosage form is given orally, the absorption process often obeys first-order kinetics. In these cases, absorption can be characterized by evaluating the absorption rate constant, ka, using plasma concentration versus time data. 

Incompatibilities have also been observed in solid dosage forms. A typical tablet contain binders, disin-tegrants, lubricants and fillers. Compatibility screening for a new drug should consider two or more excipients from each class. Serajuddin et al. have developed a drug-excipient compatibility screening model to predict interactions of drug substances with excipients [49],... 

Fractional Order. In the decomposition of pure solids, the kinetics of reactions can often be more complex than simple zero- or first-order processes. Carstensen [88] has reviewed the stability of solids and solid dosage forms as well as the equations that can be used in these cases. In addition to zero- and first-order kinetics, solid-state degradations are often described by fractional-order equations. 

In the time path solid dosage forms (tablets or capsules) must eventually to be manufactured for the clinic... 

If the areas under the curves are denoted by A, then (based on equal dose) All/Al is the fraction absorbed by oral route. Alll/All is the fraction efficiency of the solid dosage form. The reason for this latter is, of course, that the solid dosage form has to dissolve before the drug contained in it is available for absorption. It is the latter ratio that is important to the investigating pharmaceuticist, and therefore the outcome of the parenteral form is actually not a consideration from a formulation point of view. It is critical overall and if it is low, it may, at the point of parenteral data acquisition, be advisable to stop the program and evaluate the possibility of derivatives that would give better availability. 

J. T. Carstensen, Pharmaceutics of Solids and Solid Dosage Forms, Wiley-Interscience, New York, 1977, pp. 6, 41. 

The most common solid dosage forms in contemporary use are tablets, which may be defined as... 

Some tablets combine sustained-release and rapid disintegration characteristics. Products such as K-Dur (Key Pharmaceuticals) combine coated potassium chloride crystals in a rapidly releasing tablet. In this particular instance, the crystals are coated with ethylcellulose, a water-insoluble polymer, and are then incorporated into a rapidly disintegrating microcrystalline cellulose (MCC) matrix. The purpose of this tablet is to minimize GI ulceration, commonly encountered by patients treated with potassium chloride. This simple but elegant formulation is an example of a solid dosage form strategy used to achieve clinical goals. 

Another area of interest is that of microbiological contamination of solid dosage forms, which is thought to arise chiefly from raw materials rather than the... 

Colorants do not contribute to therapeutic activity, nor do they improve product bioavailability or stability. Indeed, they increase the cost and complication of the manufacturing process. Their main role is to facilitate identification and to enhance the esthetic appearance of the product. In common with all material to be ingested by humans, solid dosage forms are severely restricted in the coloring agents that are allowable. This situation is complicated by the lack in international agreement on an approved list of colorants suitable for ingestion. 

With liquid and semi-solid dosage forms, the rate and the extent of desorption are influenced by the solvent system of the preparation, pH, and temperature conditions during processing and storage. If a severe problem exists, it will usually manifest itself via an outward sign, such as container collapse, product discoloration, or precipitation [14]. 

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