Capsules have evolved and advanced over the years into a versatile dosage form. From a variety of capsule shell materials to choose from to different capsule sealing techniques and the flexibility of encapsulating different materials – capsules have come a long way. The developmental advancements in capsule technology have enabled nutraceutical manufacturers to exercise high flexibility in enhancing the product characteristics of capsule-based formulations in response to consumer needs. As a promising and cost-effective technology to address physicochemical challenges associated with the use of nutraceutical ingredients (most of which are naturally derived), liquid-filled hard capsule (LFHC) has shifted the paradigm of product formulation opening newer avenues for innovation.

A particularly interesting and key feature of LFHC is its ability to accommodate tablets, capsules, pellets, or a combination of these in addition to liquid fill. In this format, pellets or a formulated capsule (i.e., liquid-filled or dry-filled) or tablet is inserted inside an outer liquid-filled capsule. Each of the inner component is intended to achieve an objective (such as immediate or controlled release). LFHCs with the capacity to contain several such combination fills are an ideal carrier for multi-particulate units. Multi-particulate drug delivery systems, (that consist of multiple discrete drug-containing particles) are on the rise because of the number of advantages they offer – such as reduced risk of dose dumping, flexible release pattern, enhanced bioavailability and so on. 

With LFHCs, not only are formulators able to achieve multiple release patterns in one delivery system but also develop products with multiple active ingredients without causing incompatibility. This technology allows for delivery of compounds to two different regions of the gastrointestinal tract, and even delivery to the colon with the addition of enteric coatings. LFHCs are available in both gelatin and hydroxypropyl methylcellulose (HPMC) shells.

To summarise, LFHCs leverage its versatility with combination fills by allowing for the incorporation of multiple discrete dosage units in a single dosage form. The various possibilities that can be explored using these capsules are:

• Delivery of two or more incompatible ingredients in a single dosage form
• Multiple release profiles 
• Novel delivery system for combination therapy
• Achieving dose accuracy of multi-particulate units (powders, pellets, granules, beads)
• Better bioavailability for low water-soluble actives
• Enhanced patient/consumer adherence and convenience
• Improved product aesthetics
• Strong brand differentiation
• Effective anti-counterfeit solution (since difficult to replicate)