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ating variables for a dissolution device is important to the pharmaceutical scientist interested in product development, quality control, and research applications. Since the recognition of the fact that the dissolution rate of a drug from its dosage form can often become the rate-limiting process in the physiologic availability of the drug, interest has been focused on the development of a reliable in vitro dissolution test method that can positively characterize the in vivo dissolution rate-controlled absorption of drugs. |
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The appreciation and understanding of the role of pharmaceutical ingredients and excipients in the dissolution assessment is of paramount importance to gauging product success. The performance of the pharmaceutical product, both in vitro and in vivo, is virtually a function of the appropriate selection of the drug ingredients and its complimentary excipient(s). |
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The primary objectives of all investigations of the dissolution rate are to correlate in vitro and in vivo test results and to establish that control specifications have been met in the commercial production batches entering the market. Factors of major importance that influence the dissolution rate are categorized as follows (Banakar, 1992a). |
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1. Physicochemical factors of the active ingredient |
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a. Factors influencing dissolution |
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Polymorphism |
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Amorphous state and solvation |
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Chemical structure (acid, base, salt) |
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Complex formation, solid solution, eutectic mixture |
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Particle size |
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Presence of surface active agents |
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b. The role of the surface |
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Particle size |
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Manufacturing variables |
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2. Composition and manufacturing methods for the drug product |
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a. Tablets |
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Amount and type of excipients used |
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Applied tableting procedure |
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Size and size distribution of granules |
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Moisture content prior to tableting |
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Type and quantity of the disintegrating agent |
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Amount and type of surface active agent |
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Tableting pressure and rate |
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b. Capsules |
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Amount and type of excipients |
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Granulating procedure |
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Size and size distribution of granules and powder particles |
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