Capsules are solid dosage forms where the drug is enclosed within a hard or soft shell, typically made of gelatin. They provide rapid release of their contents once ingested. There are two main types - hard gelatin capsules which contain dry powders, granules or pellets and are filled using auger, dosator or dosing disc methods, and soft gelatin capsules which have a continuous gelatin shell surrounding a liquid inner core formed in a single operation. Capsules offer advantages like taste masking, easy swallowing and suitability for clinical trials but have disadvantages like higher cost and not being suitable for highly soluble compounds.

1. CAPSULES
• solid dosage form
• the drug is enclosed within either a hard or soft shell
 shell is typically made of gelatin
• primarily intended for oral delivery
• provide a rapid release of contents

2. Gelatin
protein, prepared from hydrolysis of collagen (animal
bones and skin)
 type A : pI = 7-9, pig skin
 type B : pI = 5, animal bones
possesses 4 essential properties
• stable when dry
• subject to microbial degradation when moist
• Digested
• absorbed

3. Hard Gelatin Capsules
contain 12 - 16 % moisture
typically filled with dry solids
 powders
 granules
 pellets
 tablets
also contain
 colorant
 preservatives SIZE VOLUME (cm3
)
000 1.37
00 0.95
0 0.68
1 0.50
2 0.37
3 0.30
4 0.21
5 0.13

5. Manufacture

13. Capsule Filling

14. Filling
operations involved
 rectification of empty capsules
 separation of caps from bodies
 filling capsule bodies
 replacing caps and ejecting filled capsules
3 basic methods for powder filling
 auger or screw
 dosator
 dosing disc

15. Capsule Filling
 auger
• semi-automatic operation
• filling based on volume
• need good powder flow properties

16.  Dosator
• fill based on weight
• continuous operation

17. Capsule Filling
 dosing disc
• filled based on weight
• continuous operation

18. Bioavailability
factors which influence bioavailability

19. Hard Gelatin Capsules
Advantages
 tasteless and odorless
 swallowing is easy
 flexibility in formulating
 uniquely suitable for blinded clinical trials
 useful for extemporaneous compounding by pharmacist
Disadvantages
 tend to be more expensive to produce than tablets
 not suitable for highly soluble salts

20. Soft Gelatin Capsules (Softgels)
• consist of a continuous gelatin shell surrounding a
liquid core
• formed, filled, and sealed in one operation
• shells are softened by addition of glycerin or
polyhydric alcohol (ex. sorbitol)
• oblong, spherical, elliptical in shape

21. Manufacture

22. Bioavailability

23. Soft Capsules
ADVANTAGES
 may contain liquids, suspensions, pastes
 rapid release of contents
 useful for drugs prone to oxidation
DISADVANTAGES
 have a greater tendency to adhere to each other
 more expensive
 increased possibility of interactions between drug and shell