What Are Soft and Hard Gelatin Capsules?
Gelatin capsules are commonly used in the pharmaceutical industry as containers for drugs. Not only are they easy to manufacture, but they do not require complex formulations to produce unlike some other drug containers.
Soft Gelatin Capsules
Also called softgels, soft gelatin capsules are a case produced from a single piece of gelatin, rather than two halves attached together. They are used for solutions not based on water, as this would dissolve the gelatin, but for oil based solutions. The active ingredients is dissolved in the oil-based solution, and once the capsule is ingested, it dissolves within the body, releasing the drug. The capsule dissolves within minutes of reaching the stomach. The soft gelatin capsule is manufactured and filled using the same machine as part of a single process, and some have the brands or dosage strength printed on then. Gelatin is hygroscopic in nature, and the gels contain between 5-14% water.
Hard Gelatin Capsules
Hard gelatin capsules, unlike the soft form, are made of two parts, the body and the cap, each of a different colour. This form of capsule holds dry ingredients in powder form. The body is first filled with the mix of active ingredients and any excipients used, and then closed with the cap using either a manual or automatic press machine.
Once ingested, the hard capsules disintegrate within three minutes and quickly release the drug inside. Hard gelatin capsules are also hygroscopic and contain a higher water content than the soft capsules at around 12-15%.
Some drugs need to be released at certain points in the body, and therefore the capsule must release the drug at an earlier time. To enable this, the capsule can be filled with target release pellets. As well as powdered ingredients, the gelatin capsules can also be used to cover premade tablets.
Although gelatin capsules are simple to produce, the gelatin can facilitate growth of bacteria. It is therefore important that gelatin capsules are inspected and analyzed to check for any signs of bacterial growth. Another aspect that must be considered is that gelatin is produced from animal bones and are therefore unsuitable for strict vegetarians. To overcome this, there are vegetarian forms available made from a form of cellulose called hypromellose.
Gelatin capsules vary in size depending on the requirement. They range from between 0.13 mL to 28 mL capacity.