Capsules are solid dosage forms in which the drug substance is enclosed within either a hard or soft soluble shell, usually formed from gelatin. The capsule may be considered a container drug delivery system that provides a tasteless and odorless dosage form without need for a secondary coating step, as may be required for tablets. Their availability in a wide variety of colors makes capsules aesthetically pleasing. Gelatin is obtained by the partial hydrolysis of collagen obtained from the skin, white connective tissue, and bones of animals. Gelatin capsule shells may be hard or soft, depending on their composition. Hard Gelatin Capsules Soft Gelatin Capsules The shells may be composed of two pieces, a body and a cap, or they may be composed of a single piece. hard-shell capsules are two piece capsules whereas soft shell capsules are one piece capsules. Hard Gelatin Capsules: Most capsule products manufactured today are of the hard gelatin type. The community pharmacist also uses hard gelatin capsules in theextemporaneous compounding. The empty capsule shells are made of gelatin, sugar, and water. Normally, hard gelatin capsules contain 13% to 16% of moisture. However, if stored in an environment of high humidity, additional moisture is absorbed by the capsules, and they may become distorted and lose their rigid shape. In an environment of extreme dryness, some of the moisture normally present in the gelatin capsules is lost, and the capsules may become brittle and crumble when handled. Therefore, it is desirable to maintain hard gelatin capsules in an environment free from excessive humidity or dryness. Advantages for HGC: Hard gelatin capsules often have been assumed to have better bioavailability than tablets. Hard shell capsules allow a degree of flexibility of formulation not obtainable with tablets. Modern capsule filling equipment makes possible the multiple filling of diverse systems such as beads, granules, small tablets and powders. Hard gelatin capsules are ideally suited for clinical trials and are widely used in preliminary drug studies. For comparative bioequivalence studies tablets can even be hidden in capsules to ensure the test being blinded. Disadvantages of HGC: The number of suppliers of shells is limited. Filling equipment is slower than tableting. Generally, hard gelatin capsule products tend to be more costly. Highly soluble salts (e.g., iodides, bromides, and chlorides) generally should not be dispensed in hard gelatin capsules. Their rapid release may cause gastric irritation owing to the formation of a high drug concentration in localized areas. Manufcaturing of HGC: Hard gelatin capsule shells are manufactured in two sections, the capsule body and a shorter cap. The two parts overlap when joined, with the cap fitting snugly over the open end of the capsule body. Some capsule shells are designed to lock in place when closed. Hard gelatin shells are manufactured by a process in which stainless steel mold pins are

1. Capsules

2. Definition and Introduction
• Capsules are solid dosage forms in which the drug substance is
enclosed within either a hard or soft soluble shell, usually formed
from gelatin.
• The capsule may be considered a container drug delivery system
that provides a tasteless and odorless dosage form without need
for a secondary coating step, as may be required for tablets.
Their availability in a wide variety of colors makes capsules
aesthetically pleasing. Gelatin is obtained by the partial
hydrolysis of collagen obtained from the skin, white connective
tissue, and bones of animals.

3. Types
• Gelatin capsule shells may be hard or soft, depending on their
composition.
• Hard Gelatin Capsules
• Soft Gelatin Capsules
• The shells may be composed of two pieces, a body and a cap, or
they may be composed of a single piece. hard-shell capsules are
two piece capsules whereas soft shell capsules are one piece
capsules.

4. Hard Gelatin Capsules
• Most capsule products manufactured today are of the hard gelatin type.
• The community pharmacist also uses hard gelatin capsules in the
extemporaneous compounding. The empty capsule shells are made of
gelatin, sugar, and water.
• Normally, hard gelatin capsules contain 13% to 16% of moisture.
However, if stored in an environment of high humidity, additional
moisture is absorbed by the capsules, and they may become distorted
and lose their rigid shape. In an environment of extreme dryness, some of
the moisture normally present in the gelatin capsules is lost, and the
capsules may become brittle and crumble when handled. Therefore, it is
desirable to maintain hard gelatin capsules in an environment free from
excessive humidity or dryness.

5. Advantages of HGC
• Hard gelatin capsules often have been assumed to have better
bioavailability than tablets.
• Hard shell capsules allow a degree of flexibility of formulation not
obtainable with tablets.
• Modern capsule filling equipment makes possible the multiple
filling of diverse systems such as beads, granules, small tablets and
powders.
• Hard gelatin capsules are ideally suited for clinical trials and are
widely used in preliminary drug studies. For comparative
bioequivalence studies tablets can even be hidden in capsules to
ensure the test being blinded.

6. Disadvantages of HGC
• The number of suppliers of shells is limited.
• Filling equipment is slower than tableting.
• Generally, hard gelatin capsule products tend to be more costly.
• Highly soluble salts (e.g., iodides, bromides, and chlorides)
generally should not be dispensed in hard gelatin capsules. Their
rapid release may cause gastric irritation owing to the formation of
a high drug concentration in localized areas.

7. Manufacture of HGC shells
• Hard gelatin capsule shells are manufactured in two sections, the
capsule body and a shorter cap. The two parts overlap when joined,
with the cap fitting snugly over the open end of the capsule body.
Some capsule shells are designed to lock in place when closed. Hard
gelatin shells are manufactured by a process in which stainless steel
mold pins are dipped into warm gelatin solutions and the shells are
formed by gelatin on the pin surfaces. Gelatin is the most important
constituent of the dipping solutions, but other components may be
present.

8. Hard Shell Sizes and Shapes
• For human use, empty gelatin capsules are manufactured in eight
sizes, ranging from 000 (the largest) to 5 (the smallest). The largest
size normally acceptable to patients is a No. 0. They provide greater
fill capacity without an increase in diameter. Although the standard
shape of capsules is the traditional, symmetrical bullet shape, some
manufacturers have employed distinctive proprietary shapes. Hard
gelatin capsules are made self-locking by forming indentations or
grooves on the inside of the cap and body portions. When fully
engaged, a positive interlock is created between the cap and body
portions.

10. Self locking system of HGC

11. Preparation of filled HGC
• The large-scale or small-scale preparation of filled hard gelatin
capsules is divided into the following general steps:
• Developing and preparing the formulation and selecting the
capsule size
• Filling the capsule shells
• Capsule sealing (optional)
• Cleaning and polishing the filled capsules

12. Preparation of filled HGC
• Developing the formulation and selecting the Capsule size
In dry formulations, the active and inactive components must be
blended thoroughly to ensure a uniform powder mix. Care in blending
is important for low dose drugs, since lack of homogenecity in
blending may result in significant therapeutic consequences. Hard
gelatin capsules are used to encapsulate about 65 mg to 1 g of
powdered material. In the extemporaneous compounding, the best
capsule size to use is determined by trial. Use of the smallest size
capsule, properly filled, is preferred. A properly filled capsule should
have its body filled with the drug mixture, not the cap. The cap is
intended to fit snugly over the body to retain the contents.

13. Preparation of filled HGC
• Filling Hard Capsule shells
When filling a small number of capsules in the pharmacy, the
pharmacist may use the punch method. An empty capsule body is
held between the thumb and forefinger and punched vertically into
the powder cake repeatedly until filled. Surgical gloves (latex or other
material) or finger cots to avoid handling the capsules with bare
fingers. Because the amount of powder packed into a capsule depends
on the degree of compression, the pharmacist should punch each
capsule in the same manner and weigh the product after capping.

14. Preparation of filled HGC
• Filling Hard Capsule shells
Pharmacists who prepare capsules on a regular or extensive basis may
use a hand operated filling machine. Various types of machines have
capacities ranging from 24 to 300 capsules and, when efficiently
operated, are capable of producing about 200 to 2,000 capsules per
hour. The required number of empty capsules is placed in the lower
plate and the upper plate. The powder is moved around on the plate
allowing the capsules to fill. It is generally necessary to use a tamper
to aid in packing the powder in the capsules to allow more powder to
be accommodated.

15. Preparation of filled HGC
After all the powder is filled in the capsule bodies, the plate with the
capsule caps is then placed on the lower plate and the plates are
pressed together. The upper plate is removed and all the capsules
checked to confirm a good seal is made with all of them. The lower
plate is removed and the capsules allowed to fall out of the plate onto
a surface for examination. Machines developed for industrial use
automatically separate the caps from empty capsules, fill the bodies,
scrape off the excess powder, replace the caps, seal the capsules as
desired, and clean the outside of the filled capsules at up to 165,000
capsules per hour.

17. Preparation of filled HGC
• Capsule sealing
Capsules may be sealed through a heat-welding process that fuses the
capsule cap to the body through the double wall thickness at their
juncture. The process results in a distinctive ring around the capsule
where heat welded. Still another process uses a liquid wetting agent
that lowers the melting point in the contact areas of the capsule's cap
and body and then thermally bonds the two parts using low
temperatures

18. Preparation of filled HGC
• Cleaning and polishing of capsules
Small amounts of powder may adhere to the outside of capsules after
filling. The powder may be bitter or otherwise unpalatable and should
be removed before packaging or dispensing. On a small scale, capsules
may be cleaned individually or in small numbers by rubbing them with
a clean gauze or cloth. On a large scale, many capsule-filling machines
are affixed with a cleaning vacuum that removes any extraneous
material from the capsules as they exit the equipment.

19. Soft Gelatin Capsules
Soft gelatin capsules (sometimes referred to as softgels) are made
from a more flexible, plasticized gelatin film than hard gelatin
capsules.
Soft gelatin capsules are made of gelatin to which glycerin or a
polyhydric alcohol such as sorbitol has been added. Soft gelatin
capsules, which contain more moisture than hard capsules, may have
a preservative, such as methylparaben and/or propylparaben, to
retard microbial growth. Soft gelatin capsules may be oblong, oval, or
round. Soft gelatin capsules are used to encapsulate and hermetically
seal liquids, suspensions, pasty materials, dry powders, and even
preformed tablets. Soft gelatin capsules are pharmaceutically elegant
and are easily swallowed.

20. Soft Gelatin Capsules
Composition of the Shell
Similar to hard gelatin shells, the basic component of soft gelatin
shells is gelatin. However, the shell has been plasticized by the
addition of glycerin, sorbitol, or propylene glycol. Other components
may include dyes, opacifiers, preservatives, and flavors. The ratio of
dry plasticizer to dry gelatin determines the hardness of the shell and
can vary from 0.3 to 1.0 for a very hard shell to 1.0 to 1.8 for a very
soft shell. Up to 5% sugar may be included to give the shell a
chewable. The basic gelatin formulation from which the plasticized
films are cast usually consists of 1 part gelatin 1 part water, and 0.4 to
0.6 parts plasticizer. The residual shell moisture content of finished
capsules is in the range of 6 to 10%

21. Advantages of SGC
• A higher degree of homogenecity is possible in liquid systems than
can be achieved in powder blends.
• Due to the liquid nature of the fill a rapid release of the contents
with potentially enhanced bioavailability.
• Soft gelatin capsules are hermetically sealed so this dosage form is
uniquely suited for liquids and volatile drugs.
• Soft gelatin capsules are available in a wide variety of sizes and
shapes. A wide variety of dosage forms can be encapsulated.

22. Disadvantages of SGC
• Sophisticated filling equipment, expertise and quality control
measures are required.
• Soft gelatin capsules are an inexpensive dosage form.

23. Preparation of SGC
Soft gelatin capsules may be prepared by
• Plate process.
• Rotary die process
• Reciprocating die process

24. Preparation of SGC
• By the plate process, a warm sheet of plain or colored gelatin is
placed on the bottom plate of the mold, and the medication
containing liquid is evenly poured on it. Then a second sheet of
gelatin is carefully placed on top of the medication, and the top
plate of the mold is put into place. Pressure is then applied to the
mold to form, fill, and seal the capsules simultaneously. The
capsules are removed and washed with a solvent harmless to the
capsules.

25. Preparation of SGC
• Most soft gelatin capsules are prepared by the rotary die process.
By this method, liquid gelatin flowing from an overhead tank is
formed into two continuous ribbons by the rotary die machine and
brought together between twin rotating dies. At the same time,
metered fill material is injected between the ribbons precisely at
the moment that the dies form pockets of the gelatin ribbons.
These pockets of fill containing gelatin are sealed by pressure and
heat. Use of ribbons of two different colors results in bicolored
capsules.

26. Preparation of SGC
• The reciprocating die process is similar to the rotary process in that
ribbons of gelatin are formed and used to encapsulate the fill, but it
differs in the actual encapsulating process. The gelatin ribbons are
fed between a set of vertical dies that continually open and close to
form rows of pockets in the gelatin ribbons. These pockets are filled
with the medication and are sealed, shaped, and cut out of the film
as they progress through the machinery. As the capsules are cut
from the ribbons, they fall into refrigerated tanks that prevent the
capsules from adhering to one another.

27. Application of SGC
Soft gelatin capsules are prepared to contain a variety of liquid, paste,
and dry fills. Liquids that may be encapsulated into soft gelatin
capsules include the following:
• Water-immiscible volatile and nonvolatile liquids such as vegetable
and aromatic oils, aromatic and aliphatic hydrocarbons, chlorinated
hydrocarbons, ethers, esters, alcohols, and organic acids.
• Water-miscible nonvolatile liquids, such as polyethylene glycols,
and nonionic surface-active agents, such as polysorbate 80.
• Water-miscible and relatively nonvolatile compounds such as
propylene glycol and isopropyl alcohol, depending on factors such
as concentration used and packaging conditions.

28. Application of SGC
• Liquids that can easily migrate through the capsule shell are not
suitable for soft gelatin capsules. These materials include water
above 5% and low molecular weight water soluble and volatile
organic compounds such as alcohols, ketones, acids, amines, and
esters. Solids may be encapsulated into soft gelatin capsules as
solutions in a suitable liquid solvent, suspensions, dry powders,
granules, pellets, or small tablets.

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