Capsules are solid dosage form in
which medicinal agent or inert substance is enclosed in a portion of gelatin.
Gelatin capsules shell may be
hard or soft, depending upon their composition. Most filled capsules are
intended to be swallowed whole. However, it is fairly common in hospital and
extended care facility for a care giver to open capsule or crushed tablets to
mix with food or drink especially tablets or other patients unable to swallow
solid dosage form.
Capsule:
This should be done with co-occurrence
of pharmacist since the drug release characteristics of certain dosage form can
be altered and adversely affect the patient. Dosage forms must be left
intactinclude among enteric coated tablets, designed for pass through the
stomach for drug release and absorption in intestine.
Extended release dosage forms
designed to provide prolonged release and medication. Sublingual and buccal
tablets, formulated to dissolve under the tongue and mouth.
If the patients could not swallow
an intact solid dosage form, an alternative product such as; chewing tablets,
instant dissolving tablets, oral liquid or nasal inhalation solution, injection
or suppositories may be complied.
Hard gelatin capsules:
Gelatin:
Gelatin is prepared by partial
hydrolysis of collagen obtained from skin, connective tissues and bones of
animals. In commercial, it is available in in fine powder a coarse powder,
shreds flasks or sheets. Gelatin is stable in air when dry but it is subjected
to microbial decomposition when it becomes moist. However, it stored
environment of high humidity, additional moisture is absorbed by capsule and
they become distorted and lose their rigid shape.
In an environment of extreme
dryness, some of the moisture normally present in the gelatin capsule is lost
and capsule brittle and crumble when handled. Therefore it is desirable to
maintain hard gelatin capsule in an environment free from exercise, humidity or
dryness, because moisture may be absorbed by gelatin capsule and affect
hygroscopic agent within many capsules are packed along with small packet or desiccant material to protect
against the absorption of atmospheric moisture. The desiccant materials most
used are dried salica gel, clay, and activated charcoal. Prolonged exposure to
high humidity can affect in vitro capsule dissolution, such change have been
observed in capsule containing tetracycline, chloramphenicol etc.
Gamma scintigraphy:
A number of methods have been
developed to track the passage of capsule and tablets through the GIT to made
their transit fine and drug release patterns. A non-invasive procedure that entails
use of gamma ray emitting radiotracer incorporated into the formulation with
gamma camera and coupled to a data recorder system.
The quantity of the material
added to allow gamma scintigraphy is small and does not compromise vivo
characteristics of dosage form being studied.
When the scintigraphy is combined
with pharmacokinetic studies the resultant pharmacoscintigrphic evaluation
rides information about the transit and drug release pattern of the dosage form
as well as the rate of drug absorption from the regions of GIT.
This method is particularly
useful in;
·
Determining whether a
correlation exists between in vivo and vitro bioavailability for immediate
release powder.
·
Assessing the integrity and
transit time for enteric coated tablets through the stomach and route.
·
Drug and dosage form
evaluation in new product development.
Manufacturing of hard gelatin capsules:
Hard gelatin capsules are
manufactured in two sections;
-
Capsule body
-
Shorter cap
1. The two parts overlap when joined with cap fitting snugly over
the open end of capsule body.
2. The shells are produced industrially by mechanical dipping of
pain or pegs of desired shape and diameter into a temperature controlled
reservoir of melted gelatin is mixture.
3. The pegs are made up of magnesium bronze are affixed to plates
each capsule of handing up to about 500 pegs.
4. Each plate is mechanically lowered to the gelatin bath, the pegs
submerged to the desired depth and maintained for desired period to achieve the
proper length and thickness coating.
5. Then pegs and plates are slowly lifted from bath and gelatin
dried by flow of hot and humidity controlled.
6. When dried each part of capsule trimmed mechanically to the
proper length, and removed from the pegs, capsule bodies and caps are joined
together.
7. It is important that the thickness of gelatin walls be strictly
controlled so that the capsules body and cap fit snugly to prevent
disengagement.
8. The pegs on which the capsules were formed are slightly longer
in diameter than the pegs on which bodies are formed.
9. In capsule shells production there is continuous dipping, drying
and removing.
10. And joining of capsules as the pegs containing plates rotate in
and gelatin bath.
Capsule sizes:
Empty gelatin capsules are
manufactured in various length, diameters and capacities. The size selected for
use in determined by the amount of material to be encapsulated. The density and
compressibility of the fill largely determine to what extent it may be packed
into capsule shell.
For human use emptying capsules
ranging in size from 000 (largest)
to 5 (smallest) are commercially
available for perception requiring compounding hard gelatin capsule permit a
wide prescribing by physician. The pharmacist may be compound capsule of single
medicinal agent or combination of agents at the precise dosage prescribed for
individual patients.
Preparation of filled hard gelatin capsule:
The large scale or small scale
preparation of filled hard gelatin capsule is divided into following steps.
Developing and preparing the formulation and selecting the size of capsule.
1. Filling the capsules shells
2. Capsule sealing (optional)
3. Cleaning and polishing the filled capsule
Soft gelatin capsules
are made of gelatin to which glycerin or a poly hydric alcohol such as sorbitol
has been added. Soft gelatin capsule which contain more moisture than hard
capsule may have preservative such as melting soft gelatin capsule may be oval,
oblong or round. They may be single colored or 2 tone or may be imprinted with
identified markings, as with hard gelatin capsules, they may be prepared with
opaquant to reduce transparency.
Soft gelatin capsules are used to
encapsulate and hermetically sealed liquids, suspensions, pasty material and
dry powders and even preformed tablets such as cod liver oil, fish liver oil
and many vitamins.
Preparation of soft gelatin capsules:
Soft gelatin capsules can be
prepared by following methods;
-
Plate process
-
Rotary die process
-
Reciprocating die process
Plate process:
Soft gelatin capsules can be
prepared by plate process by using a set of molds. In this process warm sheets
of plain and colored gelatin is placed on the bottom plate of the mold and
liquid containing medication is evenly poured on it. Then second sheet of
gelatin is carefully placed on the top of the plate of molds is put into place.
Pressure is then applied to mold
to form fill and seal the capsule simultaneously. The capsule are removed and
washed with solvent harmless to capsule.
Rotary die process:
Rotary process is more efficient
process. Most soft gelatin capsule are prepared by rotary die process by this
method liquid gelatin flowing from an overhead tank formed into 2 continuous
ribbons by rotary die machine and brought together between rotating disc.at the
same time metered fill material is infected between the ribbon precisely at the
moment that the disc from pockets of gelatin ribbions.
These pockets of fill containing
gelatin sealed by pressure and heating then separated from the ribbion use of
ribbon of two different colors results in bicolored capsule.
Reciprocating die process:
Reciprocating die process is a
process by which capsules are filled and sealed in a continuous operation plate
process. This process is similar to the rotary process in the ribbons of
gelatin are formed and used to encapsulate the fill.
The gelatin ribbons are fed
between a set of vertical dies that continuously open to close form rows of the
pockets in the gelatin ribbons. These pockets are filled with the medication
and are sealed shaped and cut out, as they process through machinery. As, the
capsule are cut from ribbons they fall into represented tanks at prevent the
capsule from adhering to are another.
Uses of Soft gelatin Capsules:
1. Soft gelatin capsules are prepared to contain a verity of
liquid, pastes and dry fill.
2. Water immiscible, volatile, and non-volatile liquids such as
vegetables and aromatic oils, aromatic and aromatic hydrocarbons, chlorinated
hydrocarbons, ethers, ester, alcohols and organic salts,
3. Water miscible non-volatile such as polyethylene glycols, glucose
and as polysorbate.
4. Water miscible and relatively non-volatile compounds such as
propylene glycol, isopropyl alcohol. Liquids that can easily migrate through
the capsule shell are not suitable for soft gelatin capsule.
Compendial requirements:
Some of the added substances are
added to the final production of the preparation.
Added substances:
Substances added to official
preparation including capsule to enhance their stability, usefulness or
elegance to facilitate their manufacturing may be used only if they;
Are harmless in the
quantities used
Don’t exceed the minimum
amount required to provide their intended effect.
Don’t impair the product
availability, therapeutic effected safely.
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