Tablets & Capsules


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10 January/February 2021 Tablets & Capsules capsule is fully closed after filling, a lock ring on each sec- tion engages to prevent the capsule from opening prior to patient use. Suppliers ship empty capsules in a pre-locked configuration, which joins the capsule cap and body but does not close the capsule to the point of engaging the lock ring. Prior to filling, separated caps and bodies are commonly referred to as loose pieces. Loose pieces may occur when using a pneumatic conveying system to trans- fer the capsules from the carton to the capsule filler. If you're finding loose pieces in the capsule filler's hop- per, the first troubleshooting step is to note the condition of the capsules in the original carton. If the capsules in the carton are intact, then the pneumatic conveying sys- tem is likely the cause. To minimize capsule separation during transfer, ensure that the system is operating at an appropriate air pressure or vacuum and that the convey- ing run is free of sharp turns. Failure to separate From the hopper, the empty capsules are fed into capsule filler and rectified to orient the caps and bodies correctly. Then, the caps and bodies are separated by vacuum into the corresponding cap and body segment bores, as shown in Figure 2. If the vacuum is insufficient or the segments are dirty, the caps and bodies may fail to separate. Depending on the equipment design, reduced vacuum at the point of separation may be the result of dirty or clogged filters, leaks in the vacuum lines, or worn bushings. Dirty segments from sticky formulations may cause the capsules to bind in the segment bores. Dents, dimples, and punched ends Dents, dimples, or punched ends on the capsule caps and bodies tend to be caused by overfilling the capsules. Overfilling occurs when the fill height exceeds the cut edge of the capsule body. You can correct this issue by raising the tamping pin height, selecting the correct dos- ing disk, lowering the formulation level in the bowl, or adjusting the machine speed. If the fill is correct, then the operator should confirm that the segments are correctly aligned and clean. Misaligned or dirty segments may cause the cap and body to bind in the closing station, which can result in the closing pins exerting too much pressure on the capsule ends and damaging the capsules. Closing pins that are misaligned with the segment bores may cause crescent moon-shaped dents on the ends of the capsules. Splits, telescoping, and tucks Splits can be caused by capsule defects such as a small cap edge, which is a minor edge deformity on the cut line of the cap, that splits during closing; the cap wall thickness being too thin; or the capsules being brittle. Splits can also occur if the capsule is overfilled with formulation prior to closing; if the capsule is overclosed due to an incorrect closing pin height setting; or if powder or granules from the fill become lodged between the cap and body during closing, which creates excess pressure on the capsule wall. Photo 1: Dented ends are frequently caused by overfilling the capsule body, which creates excess pressure during closing when the closing pin presses against the capsule dome or the counter closing plate. Figure 2 Capsule separation Cap segment Body segment Vacuum Figure 1 Two-piece capsule components Body Lock ring Cap

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