Capsules, Its Types and Preparation of Capsule

§  Capsules are dosage form containing unit doses of drugs enclosed in a soluble shell of gelatin, starch or similar material and intended to be swallowed whole orally.

§  Capsules can also be defined as dosage form in which gelatin shell used to fill an individual dose of powdered.

§  Capsules can be filled with dry material semisolid and liquids that are non-solvents of gelatin.

§  The basic empty shells are made from the mixture of gelatin, sugar and water and are clear, colorless and essentially tasteless.

Components of Gelatin:

§  Gelatin USP is a product obtained by the partial hydrolysis of collagen obtained from the skin, white connective tissue and bones of animals.

Characteristic of Gelatin:

§  Gelatin is stable in air when dry but it subjects to microbial decomposition when it becomes moist or when it is maintained in aqueous solution.

§  Soft gelatin capsules have higher moisture contents than hard gelatin capsules.

§  Hard gelatin capsules contain 9-12% of moisture.

§  If stored in highly humid environment, additional moisture is absorbed by the capsules and they may become distorted and lose their rigid shape.

§  If stored in highly dried environment, some of moisture present in gelatin capsules may be lost and the capsulesmay become brittle and may cramble when handled.

Advantages of capsules:

§  Capsules may be used for dispensing solid, semi-solid and liquid drugs.

§  Avoidance of the contact with the unpleasant odor and flavor of medicines.

§  Easy to swallow.

§  Disintegration is both satisfactory and reliable.

§  Attractive dosage form.

§  Shells can be colored to give protection from light.

§  Shells are physiologically inert and are easily and quickly digested in GIT.

§  Less adjuncts are necessary than for tablets.

§  If properly stored, the shells contain 12-15% of moisture which gives flexibility and consequently very considerable resistance to mechanical stresses.

Disadvantages of capsules:

§  Capsules are expensive than tablets.

§  They cannot be used for aqueous or alcoholic solutions as they will attack the shell.

§  Salts which are very readily soluble should not be capsulated as their sudden release will cause the irritation.

§  Deliquescent or hygroscopic substances cannot be capsulated.