Capsules and Their Applications

Study Notes

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.

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).

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.

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.

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.

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.

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.