How are Gelatin Capsules Made?
Two-piece hard gelatin capsules are one of the most popular oral dosage forms available. Makers of both nutraceutical and pharmaceutical products appreciate the way that gelatin capsules can be fully customized for branding purposes while also providing a flexible, cost-effective option that works with a wide range of formulations. Consumers appreciate the fact that gelatin capsules are easy to swallow (no worrying that the pill will melt in your mouth!) and can mask the unpleasant tastes associated with many active ingredients.
Gelatin capsule components
To understand the gelatin capsule manufacturing process, it is helpful to first understand the different components involved:
The ingredients
The main ingredient in gelatin capsules is, of course, gelatin. Gelatin is a protein made from animal products, specifically from collagen derived from the bones and connective tissues of cows and pigs.
It should be noted that the quality of the gelatin used can have a significant impact on the quality of the finished capsules. For this reason, choosing a vertically-integrated capsule manufacturer that owns and has complete control over its gelatin supply can be quite advantageous. Vertical integration also ensures that the manufacturer will have a continuous supply of gelatin, even in the face of today’s gelatin supply challenges.
In addition to gelatin, gelatin capsules can also contain water, plasticizers such as glycerin and polyhydric alcohol, colorants and opacifying agents such as titanium dioxide. Gelatin capsules made in manufacturing facilities that follow Good Manufacturing Practice guidelines do not require preservatives. For that reason, you should consider it a “red flag” if a gelatin capsule contains paraben esters—the manufacturing facility might not meet basic standards.
The design of the capsule shell
Hard gelatin capsules are made up of two parts: the capsule body and the capsule cap. Together these two cylindrically-shaped parts comprise the capsule shell.
The capsule body is designed to hold the material that will ultimately be encapsulated in the finished capsule. The capsule body has two air vents that allow air to escape from the capsule during the filling process. Its tapered rim and slightly smaller diameter enable it to fit perfectly into the capsule cap.
The capsule cap, which is about half the length of the capsule body, is designed to fit over and lock together with the capsule body. It features elongated dimples that help it maintain its precise, round diameter during the capsule joining process.
Since the two parts of the capsule shell must be separated before the fill material can be inserted, you might think that two-piece gelatin capsules are delivered in two separate pieces. Interestingly, they’re not. The capsule bodies and caps are joined together as part of the capsule manufacturing process and then separated by the capsule filling machine. This equipment is used to insert the fill material into the capsule body and then join the two parts back together again.
Gelatin capsules manufacturing process
Hard gelatin capsules are made using a 7-step dip-coating process:
Step #1: The gelatin solution is prepared by dissolving gelatin in demineralized water, heating it to a specified temperature, removing any air bubbles and then adding any desired colorants or pigments.
Step #2: Pairs of steel pins are dipped into the gelatin solution to form the capsule shells. Half the pins make the capsule bodies, while the other half, which are smaller, make the capsule caps.
Step #3: The gelatin-coated pins are rotated to ensure that the gelatin solution is evenly distributed over each pin.
Step #4: The gelatin is dried in stages until it achieves the desired level of moisture content.
Step #5: The capsules are removed from the pins and precision-trimmed to the proper length.
Step #6: The capsule bodies and caps are joined together, but only to a “pre-closed” position using a “pre-lock” mechanism.
Step #7: If desired, the finished capsules are custom printed for branding and/or product identification purposes.
Gelatin capsules customization options
Some gelatin capsules manufacturers offer a broad range of customization options, including:
Color
Both standard and custom colors are available, including the ability to match Pantone colors for branding purposes. Choose one color for the capsule body and another for the capsule cap, or make the entire capsule shell the same color. Once the capsules are filled, colored banding can also be applied.
Size
Hard gelatin capsules come in a range of standard sizes. As you can see on the chart below, size numbers are inverse to capsule size: a large capsule is size 000, while a small capsule is size 5.
Custom printing can be done during the capsule manufacturing process. Depending on the capabilities of the capsule manufacturer, print options include printing on the capsule cap, the capsule body or both, either horizontally or vertically (referred to as “axial” and “radial”) on the capsule, in one, two or multiple colors.
Quality considerations
As with most products, there are significant quality differences between different manufacturers’ gelatin capsules. Everything from the quality of the raw gelatin to the humidity in the equipment room and the design of the capsule shell itself can play a part in the finished product’s quality.
Why does quality matter? Because poor-quality capsules may not hold up or work properly on your capsule filling machines, thereby causing waste and re-work. An excellent way to test the quality of a particular brand of gelatin capsules is to schedule a manufacturing trial and see for yourself how the capsules perform.
