Soft gelatin capsules (sometimes referred to as softgels) consist of a hermetically sealed outer shell of gelatin that encloses a liquid or semisolid medicament in the unit dosage. Soft gelatin capsules are a completely sealed dosage form and cannot be opened without destroying the capsules.
Soft gelatin capsules are capsules made from a more flexible, plasticized gelatin film than hard gelatin capsules. Several advantages of soft gelatin capsules derive from the fact that the encapsulation process requires that the drug be a liquid or at least dissolved, solubilized, or suspended in a liquid vehicle.
This article focuses on the advantages and disadvantages of soft gelatin capsules.
Advantages of Soft Gelatin Capsules
The advantages of soft gelatin capsules include:
1. Soft gelatin capsules provide a patient-friendly dosage form for peroral administration of nonpalatable and/or oily liquids.
2. Solutions or suspensions with an unpleasant odor or taste can be easily ingested in a soft gelatin capsule dosage form, which offers tidy appearance and convenient ingestion.
3. The proper choice of vehicle may promote rapid dispersion of capsule contents and drug dissolution.
4. Higher degree of reproducibility is achieved during the manufacture of soft gelatin capsules than is possible with powders or granules feed in the manufacture of tablets or hard gelatin capsules since the liquid fill is metered into individual capsules via positive displacement pump.
5. Soft gelatin capsules can be particularly advantageous for low dose drugs that are lipid-soluble because it can allow greater uniformity of content between dosage units than the conventional tablet dosage form.
6. It can also be more suitable than a tablet dosage form for the encapsulation of liquid, water-insoluble drugs.
7. The capsules can be formulated to be immediate-release (IR), slow or sustained-release (SR), or enteric-coated.
8. Soft gelatin capsules are hermetically sealed as a natural consequence of the manufacturing process. Thus, this dosage form is uniquely suited for liquids and volatile drugs. Many drugs subject to atmospheric oxidation may also be formulated satisfactorily in this dosage form.
Disadvantages of Soft Gelatin Capsules
The disadvantages of soft gelatin capsules include:
1. Moisture-sensitive drugs may not be stable in soft gelatin capsules due to the relatively higher water content in soft gelatin shell (20–30% w/w).
2. The use of soft gelatin capsule shell imposes significant limitations on the drug formulations that can be encapsulated in this dosage form, that is, restricted to liquids and semisolids.
3. Soft gelatin capsules are not an inexpensive dosage form, particularly when compared with direct compression tablets.
4. The manufacturing process is relatively tedious and difficult to optimize (e.g., ribbon thickness, fill weight, and weight variation). In addition, the breakage of even one capsule during the manufacturing can lead to the coating of drug formulation on the outer surface of several other capsules. This can also happen during storage in multiple-use containers, such as high-density polyethylene (HDPE) bottles.
5. There is more intimate contact between the shell and its liquid contents than exists with dry-filled hard gelatin capsules, which increases the possibility of interactions. For instance, chloral hydrate formulated with an oily vehicle exerts a proteolytic effect on the gelatin shell; however, the effect is greatly reduced when the oily vehicle is replaced with polyethylene glycol.
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Advantages and Disadvantages of Soft Gelatin Capsules