Capsules and Their Applications

Capsules: Objectives

• Capsules are solid dosage forms enclosing medicinal agents/substances in a gelatin shell. Hard or soft shells exist.
• Capsules are commonly swallowed whole. Hospitals and care facilities sometimes open or crush them to mix with food.
• Advantages of capsules include elegance, ease of administration, portability, and tasteless/taste-masking shell, and low number of excipients.
• Disadvantages include issues with highly soluble salts (iodides, bromides, chlorides) potentially causing irritation, and capsules potentially getting lodged in the esophagus.
• Hard gelatin capsules are used in commercially available medications and clinical trials.

Hard Gelatin Capsules

• Shells are made from gelatin, sugar, and water (13-16% water content).
• They are transparent, colorless, and tasteless.
• Possible to add colorants (FD&C and D&C dyes).
• Can be opaque with opaquing agents.
• Preservatives can also be added.

Hard Gelatin Capsule Manufacturing

• Two sections: capsule body and cap.
• Shells are made by mechanically dipping pins into a heated gelatin mixture.
• Several steps involve dipping, drying, stripping, trimming, and joining.
• The manufacturing process is relatively complex, taking about 45 minutes overall (mostly drying time).

Hand-fill (punch method) for Filled Hard Gelatin Capsules

• Thoroughly blend active and inactive ingredients to ensure uniform powder.
• Consider particle size for uniform distribution.
• Mix potent drugs with inert diluents like lactose, microcrystalline cellulose, or pregelatinized starch.
• In cases of incompatible materials, consider placing one in a smaller capsule, then enclosing the other in a larger capsule.
• Capsules sizes are generally numbered from 000 (largest) to 5 (smallest), with specific volumes, densities, and capacities associated with each.

Filling the Capsule

• Place the powder on paper, flatten it, and avoid a layer thicker than 1/3 of the capsule length.
• Use surgical gloves to help keep hands and capsule clean.
• Repeatedly press the capsule body into the powder.
• Weight each filled capsule for accuracy (prescribing).
• Use capsule-filling machines (2000+ per day).
• Also consider cleaning capsules.

Sealing Techniques for Tampering Control

• Manufacturers use colored bands of gelatin (or other methods) to secure the capsule halves.
• Heat welding techniques precisely bond capsule halves.
• Low temperature, liquid wetting agents (melting-point-lowering) creating a seal.

Soft Gelatin Capsules

• Advantages: Liquid/dissolved drug formulations promote homogeneity, uniform drug release rate, and are suitable for volatile/labile drugs. The shell itself forms a barrier against oxygen thus promoting stability for some drugs.
• Disadvantages: Requires specialized manufacturing, cost can be significantly higher, and more likely interaction between drug and the capsule shell.
• Consist of gelatin plasticized by glycerin, sorbitol, or propylene glycol, plus other additives, dye, preservatives, flavor.

Vcaps Plus Hypromellose Capsules

• A recent advancement in capsule technologies providing various advantages.
• Offer quick and predictable dissolving at a range of pH levels regardless of cations/other food components.
• Advantages include low moisture content suitable for hygroscopic and moisture sensitive drugs, inert and robust against extreme storage conditions, and excellent mechanical properties.
• Plant based and renewable, globally recognized.