Materials For Making Hollow Plant Capsules

Vegetable hollow capsules use natural plant-based ingredients as an alternative to traditional gelatin. They offer advantages such as being animal-free and having a low risk of allergies, making them suitable for vegetarians and specific religious groups. The primary materials include:

1. Core Materials

Hydroxypropyl Methylcellulose (HPMC): Chemically modified from natural cellulose. It is highly stable, resistant to heat and moisture, and ideal for hygroscopic or light-sensitive drugs. It disperses easily in cold water and is internationally certified. As the mainstream choice, it accounts for over 80% of the market.

Pullulan: Produced through starch fermentation. It forms flexible, transparent films without plasticizers. With excellent oxygen barrier properties, it suits easily oxidized drugs. It is fully biodegradable and eco-friendly, widely used in premium pharmaceuticals and supplements.

Starch and Derivatives: Sourced from corn, potatoes, etc. They are cost-effective but brittle, requiring plasticizers to improve flexibility. They are mainly used in economical OTC drugs or supplements.

Sodium Alginate: Extracted from brown algae. It forms stable gels via calcium ion cross-linking, suitable for sustained-release or enteric-coated formulations. It has good biocompatibility but requires strict pH control during molding.

2. Excipients

Plasticizers: Such as glycerin, sorbitol, or PEG, used to improve flexibility and prevent brittleness.

Opacifiers: Such as titanium dioxide or iron oxide, to protect light-sensitive drugs from degradation.

Lubricants: Such as magnesium stearate or talc, to reduce friction and facilitate demolding.

Preservatives: Added only when necessary to inhibit microbial growth in moisture-containing formulations.

3. Material Selection Criteria

Selection depends on drug properties and target markets.

For hygroscopic drugs, low-moisture-permeability HPMC or Pullulan is preferred; light-sensitive drugs require opacifiers; pH-sensitive drugs should avoid sodium alginate due to its calcium cross-linking requirement. Additionally, non-animal materials are prioritized for vegetarian/Halal certifications, while Pullulan or starch-based capsules are better for eco-friendly demands.