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Pharmaceutical Capsules - Types and Size of Capsules

Pharmaceutical Capsules - Types and Size of Capsules

Pharmaceutical capsules are solid dosage forms in which the drug substance is enclosed within hard or soft soluble shells of a suitable form of gelatin.


  • Capsules are attractive in nature.
  • They are easy to handle and carry.
  • Mask the taste and odour of unpleasant drugs by enclosing in the tasteless shell.
  • Fewer adjuncts are required as compared to tablets.
  • They are economical.
  • The shells of the capsule are physiologically inert and easily digested in GIT.
  • They can alter the release rate of the drug.


  • They may be difficult for some people to swallow.
  • Hygroscopic drugs are not suitable for filling into capsule because they absorb water present in the capsule shell and make shell very brittle and ultimately lead to crumbling into pieces.
  • The concentrated solutions which require the previous dilution before administration are unsuitable for capsule because if administered as such lead to irritation into the stomach.
  • They are subjected to the effects of relative humidity and to microbial contamination.
    Deliquescent materials can’t be incorporated because they may cause hardening or brittle capsule.
  • Capsules are not suitable for extremely soluble drugs like KCl, KBr and NH Cl due to a sudden release of such compounds in the stomach can produce irritating concentration.
  • They are also not suitable for efflorescent, deliquescent and eutectic mixtures also avoid.

Types of pharmaceutical capsules

The pharmaceutical capsules have two types.
1. Hard gelatin capsule
2. Soft gelatin capsule

Hard gelatin capsule

The majority of capsule products are made of hard gelatin capsules.
Hard gelatin capsules are made of two shells:
1. Capsule body
2. Shorter cap
The cap fits easily over the open end of the capsule body. The basic hard gelatin capsule shells are made from mixtures of gelatin, sugar, and water. They are clear, colourless, and essentially tasteless.
Normally, hard gelatin capsules contain 13–16% of moisture. Hard gelatin capsule shell may lose their rigid shape and become distorted if additional moisture is absorbed upon storage under high relative humidity environment. In an opposite environment of extreme dryness, capsules may become too brittle and may crumble during handling.

Soft gelatin capsule

Soft gelatin is also known as softgel or soft elastic. Soft gelatin capsules consist hermetically-sealed soft shells. Soft gelatin capsules also contain a plasticizer, such as glycerin or polyhydric alcohol (e.g., sorbitol), to gelatin. The plasticizer makes gelatin elastic. Soft gelatin capsules come in various shapes such as spherical, elliptical, oblong, and special tube shapes with and without twist off. They can contain non-aqueous liquids, suspensions, pasty materials, or dry powders. They are especially important to contain volatile drug substances or drug materials susceptible to deterioration in the presence of air.

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