Is That “Delayed Release” Capsule Really Delayed Release?

When you choose a delayed-release capsule for your product, you do so because a delayed release is what your formulation requires. You need a capsule that will pass through the acidic environment of the stomach intact and then disintegrate in the small intestine.

Today many capsule companies are selling two-piece empty capsules that they claim have delayed release properties. The question is: Does the reality match the claims?  

To answer this question, we have taken the opportunity to check on some of these capsules and have found some interesting facts.  

Very few manufacturers of hard-shell two-piece empty capsules are able to incorporate delayed release properties within the film of the whole capsule. Instead, they simply coat the outside of the capsule with materials that can also affect the capsule’s performance and safety.   

While these coated capsules could be claimed as having delayed release properties, there are some significant drawbacks associated with taking this approach.

Some of the most important considerations are: 

1. Safety of the coating material

There is no clarity regarding the materials used to give these capsules their claimed delayed release profile. Are these materials safe to use?  

2. Distribution of the coating material

Coating a capsule is a complex task. To ensure that the delayed release properties will function as claimed, the coating film must be evenly distributed over the entire capsule, for every capsule in the lot. Unfortunately, this does not always happen. Internal studies have shown evidence that approximately 20% of these coated capsules rupture and fail within the first 10 minutes in disintegration tests, primarily because they were not properly coated.  

3. Impact on capsule functionality

Coating a capsule adds a process that stresses its mechanical capability to function properly. Studies have demonstrated that 40% of the coated capsules tend to separate during disintegration tests (i.e., the cap separates from the body). This makes the claim of delayed-release worthless because this separation exposes the filling material to the stomach’s acid media.  

As this demonstrates, claims regarding the delayed release properties of an empty capsule must be taken with caution. Clearly, not all delayed-release or enteric capsules perform as expected. To protect both your company and your consumers, evidence of performance must be assured. This is one of the many reasons why it is so important to only work with reputable capsule manufacturers that can offer both full traceability of their raw materials and reliable quality control.