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Tablets & Capsules September 2019 33 Another benefit of hard-shell liquid-filled capsules is that they can be used with hot-melt extrusions. Both gel- atin and HPMC capsules can withstand temperatures greater than 70°C, making them suitable for use with high-viscosity materials where the API requires heating to lower its viscosity for accurate filling. Applications for liquid-filled hard-shell capsule combination products Many pharmaceutical and nutraceutical companies are adding liquid-filling capabilities and combination prod- ucts to their current portfolios. Changes often involve differentiation from commonly available products and implementing innovative ideas to attract new consumers. The increase in the development of cannabis products in the past three years has partly been promoted by increasing familiarity with filling hard-shell capsules with oils. This may form part of a strategy to portray such products in a clinical light, as opposed to being merely recreational products. Like pharmaceutical APIs, certain nutraceutical ingre- dients show increased bioavailability when solubilized. A study investigating vitamin E and coenzyme Q 10 used NanoSolve technology to solubilize both ingredients. The results indicated ten- and five-fold bioavailability increases for vitamin E and coenzyme Q 10 , respectively, Scientists developing new drug products may also encounter several issues that must be tackled in the early stages. For example, during formulation studies, research- ers may identify a suitable solvent for improving bioavail- ability but then experience multiple problems once this liquid is placed into a gelatin or HPMC capsule for feasi- bility testing. Gelatin capsules may crack and HPMC capsules may dissolve. If this occurs, the problem is most likely attributable to the use of a moisture-sensitive API and a solvent that is incompatible with HPMC capsules. The only option may be to reformulate, which will likely increase costs, delay the drug development sequence, and potentially derail long-term project plans. Familiarity with the solvents used in drug development plays a vital role in this process, as the solvent must be compatible with the capsule that works best for a specific API. The same is true for ingredients used to produce banding solutions. Once the capsule is filled, a banding solution is applied to the joint between the capsule body and cap to prevent the capsules from leaking. A typical solution for banding gelatin capsules contains gelatin, polysorbate 80, colorants, and purified water. A banding solution for HPMC capsules may contain a mixture of HPMC colorants, purified water, isopropyl alcohol, and ethyl alcohol. In either case, the filled capsules may degrade if appropriate processes are not applied [7]. Figure 3 Liquid filling of hard-shell capsules with SEDDS and SENDS Empty capsules are loaded and separated by vacuum No-capsule detection Bush cleaning station by air and vacuum Station for liquid filling Filled-capsule discharge Optional station for pellet or tablet or capsule filling Capsule cap and body closing station Station for liquid filling Unopened-capsules ejection 1 2 3 4 5 6 7 8 9 10 Source: Milind Biyani. "Technology of liquid filled hard capsules." Express Pharma News Bureau. January 5, 2018.