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| Table 7 Continued | | In Vivo Parametera | | | | | Cmax | T50% | Microcapsules |  |
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Bacampicillin hydrochloride |
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| | Cmax | 1/T50% | | Flufenamic acid | | Cmax | %D60 min | |
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Uncoated tablets, capsules (SR), tablets (SR) |
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| Theophylline | | Cmax | kd | | Alproclate | |
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In vivo release rate |
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In vitro release rate |
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| OROS tablets | Oxprenolol | |
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Time to invasion |
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Time for dissolution |
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| Tablets | Molsidomine | | MDTin vivo | MDTin vitro | Film-coated tablets | Alproclate | | MT (invasion) | MDT (in vitro) | |
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Tablets (extended release) |
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| Theophylline | | a%Dn, percentage of dose dissolved in n minutes; %Tp, time to dissolve p percent of the dose; F%, bioavailability percent (relative to solution or IV); AUC, area under the plasma concentration time curve; Cmax, peak plasma concentration; Ae, amount of unchanged or total drug excreted in the urine; kd, rate constant for dissolution; MDT, mean dissolution time. | | b SR, Slow release. |
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order to arrive at pharmaceutically efficient dosage forms. Despite the huge number of such investigations undertaken and reports published, very few good correlations exist. The countless attempts to modify dissolution-rate testing equipment do not help in achieving a reasonably good and universal method that can be employed in designing a protocol for such in vitro-in vivo correlation experimentation. Such and many other factors have contributed to the development of varied and diversified theoretical as well as practical approaches in testing and correlating in vitro and in vivo data. |
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The selection of meaningful single parameters to characterize drug performance, both in vitro and in vivo, is of crucial importance. Empirical single in vivo parameters can be advantageous as their calculation may not require complex mathematical modeling, but they often exhibit enormous variability, e.g., Cmax, Tmax. Characterization of the entire concentration-time profile can be achieved by statistical moments by computation of parameters such as Mean Residence Time (MRT), Mean Dissolution Time (MDT), etc. (Yamaoka et al., 1978; Block and Banakar, 1988; Banakar and Block, 1984). |
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