Developing a Quality Capsule Product

Developing a Quality Capsule Product
by Lucy MacLoughlin

Inthe natural products industry, there are numerous dosage form options availableto product developers and consumers. In addition to the traditional capsule andtablet formats, new and novel delivery systems are an emerging trend. However,regardless of the format chosen, all have intrinsic challenges and advantagesthat must be handled from a manufacturing perspective in order to achieve afinished product that is both aesthetically pleasing and conforms to requiredspecifications. Using encapsulation as a case study, we can explore challengesfrequently encountered during encapsulation, and explore various pre-processingoptions to overcome those issues.

Aside from homogeneity of the starting blend, which isintegral to the finished product quality of all dosage forms, the key elementsof utmost importance in the production of a quality capsule are:

It is common for different materials in multi-ingredientblends to vary in particle size. Likewise, a single ingredient product maycontain clumps of aggregated powder; in both cases this lack of uniformity, ifnot addressed, will compromise the materials flow potential (and in the caseof the blend, homogeneity), leading to problems in encapsulation. Milling andscreening are two forms of pre-processing that are used to standardize particlesize. Milling breaks up clumps and larger particulates inpreparation for screening. During screening, material is passed through a finewire mesh. The powder that does not pass through the screen is milledagain and rescreened to ensure all material is of a more uniform size.

In addition to particle size, other factors such as thematerials physical characteristics affect flow potential. Sticky materials donot flow well through a powder hopper into capsule shells. In these cases, aprocessing aid may be needed to reduce the adhesiveness. Excipients such asmagnesium stearate provide lubrication, while flow agents such as silicondioxide improve flow and facilitate a consistent fill. Hygroscopic materials mayalso have poor flow characteristics, and in these cases silicon dioxide is oftenused.

When the density of the material is incompatible with thecapsules target fill weight (e.g., too dense or too fluffy), processing orfillers are required. Fluffy material can make it difficult to achieve a fillweight close to the capsule shells maximum potential capacity. In thesecases, the density of raw materials can be increased through chilsonation, orslugging. In chilsonation, raw materials are put into the chilsonators hopperand from there fed into a roller compaction device. The rollers have grooves inthem, into which the raw material is compacted under high pressure emergingafter processing as thin strips. These strips (or sometimes pellets) are thenmilled and sifted through the appropriate mesh screen to produce a powder with amore uniform particle size.

Slugging is a method of densification wherein a tablet pressis used to compress powder into large slugs, which are then milled andscreened.The high pressure the powder is subjected to compresses the particlesresulting in a larger number packed into a smaller area, again facilitating ahigher fill weight.

In the opposite circumstance where powder is too dense tocompletely fill the capsule inert materials must be added to bulk up the productto prevent headspace. Headspace is a phenomenon wherein a portion of thecapsule shell remains empty, and in the case of clear capsules, transparent.This type of capsule is substandard aesthetically and often leads consumers toquestion whether they are getting full value for their purchase. Anotheraesthetically important consideration is the luster of the finished capsules.Certain materials are particularly dusty and leave a fine film of powder on thecapsule shells. Polishing removes this film resulting in a shiny, clean andcosmetically pleasing product.

Manufacturing quality capsule products requires a goodknowledge of the physical and mechanical properties of materials, the ability toanticipate potential problems and determine contingencies to address them,personnel who are thoroughly trained on and comfortable with the encapsulationequipment being used, and quality control before, throughout and after theproduction process in a GMP (good manufacturing practice) environment.

Lucy MacLoughlin is chief operating officer with Bellingham,Wash.-based Rhema Industries Inc. (www.rhemaindustries.com). Rhema, a cGMP contract manufacturer/packager, offersformulation expertise, new product development, hard shell encapsulation, tabletpressing and coating, and more.3