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aVaries with the particular model. Abbreviation: N/A, not applicable.

aVaries with the particular model. Abbreviation: N/A, not applicable.

high-speed tablet compression or powder-filling machines for capsules and, at first sight, suggest slow processing for liquid-filled capsule products. However, these filling rates should not be considered in isolation. Although conventional tablet compression-machines can operate at 10 times the speed of these capsule liquid filling systems, the relative complexities of the overall support processes differ significantly. The current disadvantage of relatively low production rate for liquid-filled capsules is offset by the advantage of minimizing other process support activities associated with conventional tablet or capsule dosage forms. For the hard capsule dosage form, a single bulk mix is prepared and can be filled and sealed in one continuous process, whereby formulated drug entering the filling machine is converted into the package-ready final dosage unit in as little as 10 minutes, according to the particular fill-seal system used. There is no need for coating to address product appearance or to provide taste-masking properties, which obviates the need for an otherwise complex series of additional operations. Since the liquid-filling process is essentially dust-free after the initial drug powder dispensing to prepare the bulk formulation, the need for the installation, running, and maintenance of expensive air-filtration facilities is minimized. This is particularly important for such actives as cytotoxics and highly-potent drugs, such as steroids and certain drugs, which act on the central-nervous-system, where support costs in the form of containment and clean-up may not be obvious but are, nevertheless, high.

The design of the liquid handling systems used by these filling machines generally promotes clean-running. However, incidents of empty capsule-feed failure can lead to rapid contamination of machine bushes and external capsule surfaces, resulting in the failure of any subsequent capsule sealing process. The availability and robustness of the filling machine for detecting missing capsule parts in the empty capsule feed system and its ability to subsequently halt the liquid filling pump or machine operation are critical features of these machines. Methods for detecting missing capsule parts may function by mechanical, light or pneumatic methods, or by combinations thereof, depending on the particular machine manufacturer, with each method having its advantages and disadvantages. For example, light-based fault detection systems may not be suitable for use with clear capsules. On the other hand, mechanical fault detection systems may stick whereas pneumatic systems may be vulnerable to the presence of shell fragments. Clean-running is also promoted by degassing of bulk fill material and by appropriate filling-nozzle design. These features are important in avoiding droplets or "pig-tailing" at the filling-nozzle tips, which is a common cause of bush contamination. Maintaining clean nozzle tips is also promoted in certain machines by mechanisms, which make a final, sharp movement between the capsule and nozzle at the end of the filling stroke, giving a "clean break" in the fill material stream at the nozzle tip.

In addition, useful output rates for filling machines need to be matched to those of the corresponding sealing units in order to minimize the time interval between initial capsule filling and final sealing during which leakage of the contents may occur. Currently, practical maximum output rates for single fill/seal machine combinations are around 60 k capsules per hour.

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