Nature of the Shell:
Soft gelatin capsules (softgels) consist of a single, seamless, and pliable shell that encloses the drug or formulation in liquid or semi-solid form. (Nature of Shell)
The shell is primarily composed of:
Gelatin: The main component, derived from animal collagen (Type A or Type B).
Plasticizers: Substances like glycerin, sorbitol, or propylene glycol are added to make the shell flexible and soft.
Colorants and Opacifiers: Enhance appearance and prevent photodegradation. Titanium dioxide is commonly used as an opacifier.
Preservatives: Like methylparaben and propylparaben, to prevent microbial growth.
Key Characteristics:
Soft and elastic, unlike hard gelatin capsules.
Acts as a barrier against oxygen, moisture, and light.
Nature of Capsule Content:
Softgels are designed to encapsulate liquid or semi-solid formulations, including:
Solutions: Drugs dissolved in non-aqueous solvents (e.g., oils like soybean or medium-chain triglycerides).
Suspensions: Drugs dispersed in a suitable liquid carrier.
Emulsions: Oil-in-water or water-in-oil emulsions.
Microemulsions or Self-Emulsifying Systems: Formulations that enhance bioavailability of poorly water-soluble drugs.
Exclusions:
Aqueous formulations cannot be encapsulated in softgels as water can degrade the gelatin shell.