Encapsulation capsule dosage form

Unlike the tablet dosage form, dmg particles in a capsule are not subjected to high compression forces, which tend to compact the powder or granules and reduce the effective surface area. Hence, upon disruption of the shell, the encapsulated powder mass should disperse rapidly to expose a large surface area to the G1 fluid. This rate of dispersion, in turn, influences the rate of dissolution and, therefore, bioavailability. It is, therefore, important to have suitable diluents and/or other excipients in a capsule dosage form, particularly when the drug is hydrophobic (Fig. 9.3). 

Figures 23.3 through 23.5 illustrate the stepwise process low typically utilized in wet and dry granulation techniques for the manufacture of tablet dosage forms. For capsules, the process tends to be simpler with utilization of Lrst three steps from dry granulation followed by encapsulation in appropriate-size capsule shells. Depending on the batch size, a manual LHer (e.g., Bonapace), semiautomatic encapsulator (e.g., Capsugel Ultra 8), or automated encapsulator (Zanasi, Macofar, etc.) could be utilized for manufacturing.

Encapsulation is a critical step in the production of capsules, similar to the compression step for tablet dosage forms. The materials to be encapsulated will need to have good flow properties and a consistent density. The materials may also need to be compressible in order to be dosed into the capsules however, they should also be easily deaggregated so not to adversely affect the dissolution of the drug. 

The manufacture and formulation of hard gelatin capsules has not been the subject of as much research as tabletting, partly because encapsulation unlike compression is not a science shared by many other disciplines. Nevertheless, there has been important work performed on this dosage form, and much of it is captured in Hard Capsules Development and Technology (Ridgway 1987). 

The capsule has the potential to be an efficient drug delivery system. The hard gelatin shell encapsulating the formulation should disrupt quickly, and expose the contents to the G1 fluid, provided that excipients in the formulation and/or the method of manufacture do not impart a hydrophobic nature to the dosage form. 

Powders as such or encapsulated into hard shells (capsules) are alternatives to tablets. They are needed for example to obtain appropriately sized dosage units for children. Both powders and capsules are relatively easy to prepare (Ml a small scale. Often, pharmacists use commercially available medicines as a starting point to prepare the dosage forms, rather than starting ab initio from the active pharmaceutical substance with selected excipients. Pulverised tablets (if possible) can be used for the preparation of capsules with a lower dose than the one present in tablets intended for adults. Alternatively, the contents of capsules can be diluted to provide the dose required by the patient. 

In most cases, an entire batch of powder blend or granulation is encapsulated or tableted, then a random sample of capsules or tablets drawn and analyzed prior to final release. Failure of a sample often means rework or disposal of the entire batch. Characterization of intact dosage forms by NIR is a significant advantage because it offers the potential for on-line or at-line qualification of dosage forms. Loss of batches could be avoided, because problems could be detected and addressed immediately. 

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