by Steve Lee
Speed is a critical factor when taking new products to market. For solid-dose formulations, marketing and product development personnel must consider how the dosage form chosen will affect the speed in which the product reaches the shelf. From a manufacturing standpoint, capsules will save time in several key areas.
The two-piece capsule reduces the time and materials needed for formulators developing solid-dose products, as the capsule is a “ready-made” container for the dose. For tablets, formulators must start at ground zero each time, overcoming obstacles of compressibility, hardness, thickness, friability and disintegration. To overcome these challenges, a greater number of excipients must be sourced, tested and qualified for performance. In producing capsules, formulators can rapidly determine universal factors such as flow and lubricity, sending the product to manufacturing much more quickly. In addition, when working with tablets, new tooling sizes or shapes can add four to six weeks to the start time.
Perhaps the greatest savings are realized in the material preparation stage. Capsule formulations require fewer processing steps and less equipment. For capsules, the process is simple: weigh, blend, encapsulate. To develop powder for tableting, the particles must have the proper characteristics for strong bonding, without sticking to punch surfaces. The product development team will determine whether to use direct compression or a prepared granulation. When using direct compression, higher compression forces will lead to more money spent on tooling and press parts, while having a greater tendency for processing issues. To alleviate, many choose to develop a tablet granulation. The process to prepare a granulated blend for tableting is intensive in terms of time, equipment and personnel. And each step of the process requires operators, equipment, cleaning, process validation and quality involvement, and presents another opportunity for failure.
First-time products in scale-up manufacturing can be unpredictable and troublesome. When running capsules or tablets, an area of difficulty is often weight variation. To combat this, most capsule-filling machines are designed with multiple tools to help overcome inconsistencies. On tamping style fillers, there are five adjustable stations used to prepare and fine tune the product dose. Other tools such as bowl level, dosing disc size and machine speed can also be used effectively to regulate product weight.
Tablet weight is a measure of volume, dependent on the product to flow consistently into the die. If product development does a good job with the granulation procedure, and if the manufacturing group prepares the material correctly, no problem. However, if one of the many preparatory steps is not completed correctly, product re-work will likely be required. Most tablets are also coated, which represents another step, another machine and an opportunity to lose the whole batch if not carefully controlled.
Two-piece capsules offer many benefits over other delivery systems. On one hand, capsules are inherently easy to swallow, have no unpleasant tastes or odors and therefore are preferred by many consumers over other delivery systems including tablets. According to a study of patient preferences, 66 percent of patients preferred capsules, with 18 percent preferring coated tablets and 4 percent uncoated tablets (Pharm World Sci. 2001 Oct;23(5)185-8).
Additionally, capsules play an important role in building brand recognition, as companies can choose customized two-color capsules with many print options, greatly increasing brand identity. All this can be done in advance through the supplier of empty capsules.
Steve Lee is the technical service manager with CapsCanada (CapsCanada.com) .