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Pills, until almost completely replaced by compressed tablets around the middle of this century, were the most widely used dosage form. By definition, they were small spherical or ovoid products incorporating a medicinal agent in a doughy matrix. The pill mass consisted of two parts: the active ingredient, and the excipient used to form the pill, giving it the proper consistency and acting as a diluent. |
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Great strides have been made in the management of disease through the intervention of drugs over the past decade. This has been effected with the concomitant recognition of various intricacies associated with the treatment of numerous diseases. Simultaneously, the area of the pharmaceutical technology has undergone a tremendous change in the last decade from the standpoint of maturation as well as implementation of innovative ideas in the process of drug development. This has been coupled with the various intriguing, if not fascinating, attempts to design and fabricate novel drug delivery systems. Yet, the primary concerns governing drug product development such as excipients in dosage forms, dissolution modeling in dosage form design, and the ever-bearing, in vitro-in vivo correlation have not been clearly understood. This chapter focuses on these three areas. First, it provides an insight into the importance of the role of excipients in pharmaceutical drug development. Second, it demonstrates the significance of simulation (modeling) of dissolution performance in the design of dosage forms through the use of the Makoid-Banakar function. Finally, it presents a new approach to correlate in vitro-in vivo data employing the System Response Correlation Concept. |
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II. Role of Excipients in Drug Development |
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The choice of the proper excipient required, if not mandated, is dependent on the formulator's knowledge of chemistry, materia medica, and physics. The bulk of the final product in dosage forms such as tablet, capsule, etc., the speed of disintegration, rate of dissolution/release of drug, protection against moisture, and stability during storage, as well as compatibility, are determined by the excipient(s). |
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Excipients can be divided into three categories: |
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Adhesive excipients commonly used include such materials as syrup, honey, acacia, tragacanth mucilages, starch glycerides, glycerin, etc. Their purpose, |
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