Over-encapsulation involves the blinding of a solid dosage form (e.g. capsule, tablet) into another capsule shell. It is now a widely accepted blinding method used throughout the pharmaceutical industry.  The principle of over-encapsulation is simply the addition of product to a hard gelatin capsule, which may be backfilled with an inactive excipient. This process can be used for comparator products, investigational supplies and/or placebos, providing our clients with visually identical capsules for each product and strength.

Key aspects of the over-encapsulation process include:

  • Selection of Capsule Shell – Importance should be placed on selection of a capsule specifically designed for the process including double locking body/cap and appropriate shell coloring.
  • Selection of Back-fill Component – Select a suitable excipient present in the dosage form to be over-encapsulated with the use of additional lubricants minimized.
  • Selection of Over-Encapsulation Method – Manual and automatic options available.

Depending on the quantity of material to be over-encapsulated, the shape of the product and the number of input components, we maintain a series of processes available to meet your needs.

At VxP Pharma, we utilize manual and semi-automatic capsule fillers, and fully automated fillers. This equipment can also be used for the straight fill of powders and liquid-in-capsule dosage forms as well.  For smaller scale projects (<1000 units) we have bench top capsule filling equipment available.


  • Precisely over-encapsulate uniquely shaped tablets so your actives, comparators and placebos are concealed
  • Enable blinding without altering the dosage form
  • No need for time-consuming splitting, grinding or coating tablets which can alter the dosage form
  • Minimum stability testing and potentially no bioequivalence testing required, reducing your product development time
  • Use of inactive excipients (backfill) reduces unnecessary regulatory compliance

We have experience with these and other creative approaches to blinding study materials.  Give us a challenge, and we’ll propose a compliant and cost-effective solution.  Our seasoned scientists have the knowledge and equipment to customize your over-encapsulation project and suit your specific clinical trial needs today.

Contact us today for a free consultation with our scientific team and discover how VxP can be a valuable resource and partner for your organization.