Solid Dosage Forms: Processing of Capsules

What are the 2 types of capsules?

• Regular capsules

• Controlled release systems

What are the 2 types of regular capsules?

• Hard gelatin

• Soft gelatin

What are 2 types of controlled release systems in capsules?

• Coated granules

• Coarse dispersion

Capsules may not be first choice (compared to tablets) due to speed of production.

Why do we use hard shell capsules?

• Hard capsules can hold bulk drugs

• Capsules are useful for drugs that are not suitable for compression

• Capsules can be used in dry powder inhalers

Where do you get gelatin?

• Gelatin is a protein substance commonly derived from collagen from animals

• It is produced by partial hydrolysis of connective tissues

• There’s type A gelatin produced by acid hydrolysis and type B gelatin produced by basic hydrolysis

How do you manufacture empty capsules?

• Hard gelatin capsules have 2 parts. A cap and a body.

• Soft gelatin capsules are one operation.

How do you fill a gelatin capsule?

A dosator. You can control how much amount you can put in.

Why are glidants and lubricants added?

Reduces friction and improves flow

Why are diluents added?

They are required for low dose drugs

There is non-powder filling of hard gelatin capsules/

A variety of materials other tan powders can be filled, like granules and pellets, semi solids, non aqueous liquids.

The self locking capsules lock in the non powder filling

What are the potential problems with capsules?

• Crosslinking

  • Gelatin crosslinking reactions may make the capsule insoluble

• Embrittlement

  • Water loss to fill material or atmosphere causes brittle capsules to crumble

• Sticking/solvation

  • Water entry hydrates the capsule, making it sticky and may start to dissolve

• Leaking

  • Poor seal at the capsule body may cause leaking

Soft gelatin capsules

• Made of continuous gelatin shell surrounding a liquid or semi-solid matrix material

• Compounds which are soluble or dispersible in oil, hydrophilic liquids, or a combination benefit from formulaton as a soft gelatin capsule

• Capsules are formed, filled, and sealed in one operation

• There are many different sizes and shapes

What are the advantages of soft gelatin capsules?

• No need to compress drugs (these drugs are usually poorly compressible at high doses)

• No drug content uniformity and powder flow issues as drug is dissolved or dispersed in a liquid which is accurately dosed volumetrically.

• There is chemical stability of dispersed drug (the oily vehicle will protect drugs sensitive to oxidation or hydrolysis)

• Drug formulations as self-emulsifying oils increase oral bioavailability

What are the limitations of soft gelatin capsules?

• Drugs or excipients containing high concentration of water or other gelatin solvents cannot be incorporated

• Not great for o/w or w/o emulsions, which will become unstable as water is lost from shell

• Surfactants affect the capsule seal

• You have to avoid pH below 2.5 and above 7.5