Galenicals
Syllabus:
Principles and methods of preparation of extraction,
preparation of infusions, decoctions, tinctures, liquid, soft and dry extracts.
Introduction and classification of dosage forms.
Reference Books:
1.
Introduction to Pharmaceutics - A.K.Gupta [Diploma -
1st year]
2.
Pharmaceutics - R. M. Mehta [Diploma - Ist year]
3.
Remington’s Pharmaceutical Sciences.
4.
Cooper & Guns Dispensing
5.
Cooper & Gun’s Tutorial.
6.
Bentley’s Text Book of Pharmaceutics.
EXTRACTION
Definition:
extraction involves the
separation of medicinally active portions of plant or animal
tissues from the inactive or inert components by using selective
solvents in standard extraction procedures.
N.B.
Belladonna extract is obtained
from the leaves of the plant Atropa belladonna.
The active ingredient is atropine. Besides atropine, starch, lignin, pigments
etc. are also present. So to extract the atropine from the leaves a selective
solvent has to be used so that only atropine is soluble in it. Thus the active
ingredient can be separated from the plant.
Source of drugs (active
ingredients) may be plant or animal.
Plant source: Emetine
from Ipecac root,
reserpine
from Rauwolfia serpentina root,
atropine
from Belladonna leaves.
Animal source: Cochineal
from insect Coccus cacti.
General procedures:
Let us take some dried leaves
(known as the crude drug) in a
container, add water in it. The active ingredient will come out in the water.
Here water, i.e. the solvent of extraction is called menstruum. Later the water is filtered.
The filtrate is known as the extract.
The damp crude drugs (damp leaves) are called marc. This marc can be expressed i.e., pressed in a chamber
to get the residual liquid, which is mixed with the previous extract.
 |
MACERATION
Principle:
In this process solid ingredients
are placed in a stoppered container with the whole of the solvent and allowed
to stand for a period of at least 3 days (3 - 7 days) with frequent agitation,
until soluble matter is dissolved. The mixture is then strained (through sieves
/ nets), the marc pressed and the combined liquids clarified (cleaned by
filtration) or by decantation, after standing.
N.B.
Stoppered container is generally taken to reduce the
loss of solvents by evaporation. If the volume of solvent is reduced by
evaporation then the extract may become concentrated, which may not be desired.
The drug is allowed to stand for few days
i) to help the solvent to
penetrate the cells of the drugs,
ii) to provide the time for
partitioning the active ingredient into the solvent and
iii) to transfer the drug out of
the cells into the bulk of the solvent.
Frequent agitation is required to reduce the
localized concentration around the cells and tissues.
Organized drug:
Unorganized
drug:
Classification:
1.
Simple maceration
- a process for tinctures made from organized drugs e.g. roots, stems, leaves
etc.
2.
Maceration with
adjustment - a process for tinctures made from unorganized drugs such as
oleo-resins and gum resins.
3.
Multiple
maceration - a process to prepare concentrated extract. It includes ‘Double
maceration’ and ‘Triple maceration’.
SIMPLE MACERATION
Crude drugs: Organized drugs having specific cell
structures like roots, stems, leaves, flowers etc. are extracted by this
procedure.
Apparatus
A wide mouthed bottle or any other
container, which can be tightly closed. This is required to prevent the loss of
menstruum by evaporation.
Method
Water or alcohol is used as
menstruum and the drug menstruum ratio is 1 : 10.
·
The drug is placed with the whole of the
menstruum in a closed vessel for seven days. During this period shaking is done
occasionally.
·
After 7 days the liquid is strained and marc is
pressed.
·
The expressed liquid is mixed with strained
liquid.
·
It is then filtered to make a clear liquid.
·
The final
volume is not adjusted.
N.B.
·
Shaking of the drug during maceration is essential in order to replace
the saturated layers around the drug with fresh menstruum.
·
After straining, the marc is pressed in a filter press, hydraulic press
or hand press etc. The marc can be squeezed out of a fine muslin piece, when
the quantity of the drug is very small.
·
The pressed liquid is mixed with the strained liquid and then filtered.
No final adjustment is made, since the volume of pressed liquid is likely to
vary with the process of pressing the marc. If the final adjustment in volume
is made, it will give variation in the concentration of active principle
although the volume of the final preparation may be the same.
·
Filtration is necessary to remove insoluble cell contents obtained
during the pressing of marc.
Examples: The tinctures made by simple maceration process are-
1. Tincture of Orange 2. Tincture of Lemon 3.Tincture of Squill
MACERATION WITH ADJUSTMENT
Crude drugs: The process
is used for unorganized drugs.
Apparatus: Same as simple
maceration.
Method:
·
The unorganized drug is placed with 4/5th
of the menstruum in a closed vessel for a period of 2 days. During this
period, shaking is done occasionally .
·
After the stated period, the liquid is filtered
and the volume is made up by passing the remaining 1/5th of
the menstruum through the filter.
·
The marc is not pressed.
Example
1.
Tincture of tolu
2. Compound
tincture of benzoin.
N.B.
1. 
The period of maceration is reduced from 7 to 2 days
in some cases, because the unorganized drugs behave like simple chemicals that
dissolve in the solvent very easily and quickly.
The period of maceration is reduced from 7 to 2 days
in some cases, because the unorganized drugs behave like simple chemicals that
dissolve in the solvent very easily and quickly.
2. 4/5th of the menstruum is
used to keep the drug in contact with it in order to take into account the
increase in volume after dissolving the soluble matter of the drug. The volume is
made up at the end with 1/5th of the menstruum remained.
3. The marc left is a compact
gummy matter. It does not retain the menstruum and hence it is not necessary to
press the marc.
4. The final volume is made up
because all the active constituents of drug get dissolved in the menstruum.
Marc is not pressed. hence, there is no change in the concentration of the
preparation in case the final volume is made up.
MULTIPLE MACERATION
Multiple maceration process is
carried out in the same way as simple maceration process, but the menstruum
used is divided into two parts in double maceration process and three parts in
triple maceration process
Double
maceration process:
In this process, the drug is macerated twice by using the
menstruum which is divided into two parts in such a manner that the same volume
is used for each maceration.
Total volume of menstrrum =
Volume1 + Volume2
Volume2 = Total vol. of menstruum - Vol. of menstruum used in first
maceration
N.B. The volume of menstruum to be retained by the drug
is determined by experiment, in a test batch of drug by adding a known volume
of menstruum to known weight of the drug. After maceration, straining and
pressing of the marc, measured volume of liquid (extract) is obtained. Difference
in the volume of extract and the volume used represents the volume retained by
the weighable quantity of the drug used.
Method
1.
The crude drug + Volume-1 ®macerated for 48 hours ®
liquid is strained and the marc is pressed ® Extract-1.
2.
Marc + Volume-2 ® macerated for 24 hours ®
liquid is strained and the marc is pressed ® Extract-2.
3.
Extract-1 + Extract-2 ® mixed and allowed to
stand for 14 days ®
filter.
Examples:
The following concentrated
infusions are prepared by double maceration process:
1.
Concentrated infusion of orange.
2.
Concentrated compound infusion of chirata.
3.
Concentrated compound infusion of gentian
Triple maceration process
In this maceration process, the
drug is macerated thrice by using the menstruum which is divided into three
parts in such a manner that the same volume for three parts is used for each
maceration. The quantity of menstruum required for three macerations is
calculateas follows:
Total volume of
menstruum = Volume 1 +
Volume 2 + Volume 3
Volume2 = Volume3
= 
Method
·
The whole of the drug + Volume1 ®
macerated for one hour® strained. ® Extract-1 is collected.
·
The marc + Volume-2 ® macerated for one hour ®
strained. ®
Extract-2 is collected
·
The marc + Volume-3 ® macerated for one hour ®
strained. ®
Extract-3 is collected.
·
Extract-2 + Extract-2 ® evaporated to a specified
concentration. This concentrated liquid is mixed with Extract-1.
·
90 % alcohol equal to 1/4th of the volume of the
finished product is added.
·
Volume adjusted with water and allowed to stand
for 14 days and then filtered.
Examples
The following concentrated
infusions are prepared by triple maceration process:
1.
Concentrated Infusion of Quassia
2.
Liquid Extract of Senna
PERCOLATION PROCESS
1. Simple percolation process
2. Percolation process for
concentrated preparations
(a)
Reserved percolation
(b)
Modified percolation
3. Continuous hot percolation /
Soxhlet Extraction / Soxhlation
SIMPLE PERCOLATION
Apparatus:
Three types of apparatus are
generally used,
i)
Conical percolator
ii) Cylindrical
percolator
iii) Steam
jacketed percolator [for higher temperature extraction]
Stages:
1. Size reduction:
The drug to be extracted is
subjected to suitable degree of size reduction, usually from coarse powder to
fine powder,
i)
to increase the surface area of the drug exposed to the
menstruum,
ii) for
uniform packing of the percolator,
iii) to
slow down the movement of the menstruum and
iv) to
ensure complete exhaustion of the drug.
2. Imbibition:
During imbibition the powdered
drug is moistened with a suitable amount of menstruum and allowed to stand for
four hours in a well closed container. During this period the drug swells up as
the menstruum penetrates the cell walls. The preliminary moistening of the drug
is necessary because:
i) the
dried tissue swells when it comes in contact with the menstruum but if packed
in the dry condition subsequent swelling will reduce the porosity of the
material and choke the percolator,
ii) the
air present in the interstices (in between particles) is removed by menstruum,
which will otherwise disturb the packing of the percolator due to which the
menstruum will run through the channels results in inefficient extraction,
iii) it
does not allow the fine particles to be washed out of the percolator during
percolation.
3. Packing:
After imbibition the
moistened drug is evenly packed into the percolator. Cotton wool or fibres of
flax; previously moistened with menstruum is placed on the perforated plate of
the percolator.
The packing should not be too tight, it will lead to slow
extraction rate. Similarly, loose packing will allow the menstruum to pass
through quickly resulting in incomplete contact with the drug.
The drug should occupy 2/3rd
capacity of the percolator. After packing , a piece of filter paper is placed
over top of the bed, on which small quantity of washed sand is placed to
prevent disturbance of the packed material.
4. Maceration:
After packing sufficient
menstruum is added to saturate the material. When the liquid begins to drip
from the bottom of the percolator, the tap fitted at its bottom is closed. More
menstruum is added if required, so that a shallow layer of menstruum is
maintained over the drug bed.
The percolator is allowed to
stand for 24 hours to macerate the drug.
5. Percolation:
After 24 hours maceration, the lower
tap is opened and liquid collected therein is allowed to drip slowly at a
controlled rate until 3/4th volume of the finished product is obtained.
Sufficient amount of menstruum is
simultaneously added over the drug because at no time packed material should be
allowed to become dry. After collecting 3/4 th volume, the percolate is tested
for complete exhaustion of the drug by various tests.
Tests to check complete
exhaustion of the drug:
i)
Take a few ml of the last percolate and evaporate to
dryness, it no residue remains - it shows that the drug is completely
exhausted.
ii) The
specific gravity of last few ml of percolate is measured. If it is equal to the
specific gravity of the fresh menstruum the exhaustion is taken to be complete.
iii) Specific
chemical tests may be performed on the percolate for the drugs containing
alkaloids, glycosides, tannins, resins or bitter constituents.
·
The marc
is then pressed and the expressed liquid is added to the already
collected percolate.
·
More menstruum is added to produce the required
volume.
·
The liquid is then allowed to stand to settle
the suspended particles, decanted or clarified by filtration.
Examples:
i)
Tincture of belladonna
ii) Compound
tincture of cardamom
iii) Strong
tincture of ginger etc.
2.(a) RESERVE PERCOLATION
·
In this process, the first portion (about 3/4 th
of the final product) of the percolate which contains the maximum amount of
active constituents is reserved. Subsequently, percolation is completed as
usual until the drug is exhausted but the last part (about 1/4th of the final
product) is collected separately.
·
The second dilute part is then evaporated to get
a syrupy consistency which is then mixed with the reserved first portion of the
percolate.
·
Finally volume is adjusted by adding more
menstruum.
Example:
Liquid extract of liquorice
Advantages:
i)
The reserved part of the percolate which contains the
maximum amount of dissolved active principles is not subjected to heat, only
the dilute portion is evaporated. Hence, the major portion of the active
constituents of the drug are saved from deterioration.
ii) The
process is economical as the whole of the percolate is not evaporated.
2.(b) MODIFIED PERCOLATION
In percolation process for
preparation of tinctures the drug/percolate (d/p) ratio is about 1:4. The d/p
ratio is reduced to 1:3 by modifying the percolation process and hence, there
is a lot of saving in heat, time and menstruum.
Example:
In simple percolation process:
Drug Imbibition Maceration Percolation and collect
the
(1000 g) (for 4 hrs) (for 24 hrs) percolate, i.e. 3/4th of the
volume
of finished preparation
Drug : Percolate = 1000
g :
4000 ml = 1 : 4
In modified percolation process:
Drug Imbibition Maceration Percolation and collect
(1000 g) (for 4 hrs) (for 24 hrs) 1000 ml of percolate
Maceration Percolation &
collect
(for
12 hrs) 1000 ml of
percolate
Maceration Percolation &
collect
(for
12 hrs) 1000 ml of
percolate
Drug : Percolate = 1000
g :
3000 ml = 1 : 3
CONTINUOUS HOT PERCOLATION PROCESS / SOXHLET EXTRACTION / SOXHLATION
This process is used for those
drugs
·
where the penetration of the menstruum into the
cellular tissues is very slow and
·
the solute is not readily soluble into the
solvent and
·
the quantity of the menstruum is very less.
In such cases Soxhlet extractor
is used where small volume of hot menstruum is passed over the drug time and
again to dissolve out the active constituents until the drug is exhausted. The
process is known as Soxhlation.
Apparatus:
i)
A round bottom flask in which the menstruum is boiled.
ii) An
extraction chamber in which drug is filled, is fitted with side tube and a
siphon.
iii) A
reflux condenser.
The size of the drug is reduced.
The drug is packed in a ‘thimble’ made of filter paper which is
then placed into the wider part of the extractor.
[N.B. thimble is used to
prevent choking of the lower part of the extractor.]
Menstruum is placed in the flask
and boiled. The vapor rises through the side tube to the condenser, where the
vapor is condensed and fall on the packed drug, through which it percolates and
extract out the active constituents.
As the volume of menstruum in the
extractor increases, the level of liquid in the siphon also increases till it
reaches the maximum point from where it is siphoned out into the flask.
On further heating the menstruum
vaporizes while the dissolved active constituents remain behind in the flask.
The alternate filling and emptying of the body of the extractor goes on
continuously till the drug is exhausted. Thus the same quantity of menstruum is
made to percolate repeatedly, about 14 to 15 times through the drug and the
active constituents are collected in the flask.
Limitations of continuous hot percolation process:
1.
Physical character of the drug: If the physical
character of the drug is such that it would block the Soxhlet apparatus then
this method is not suitable. e.g opium, gum, resin, orange peel etc.
2.
Solvent: Only pure solvents or constant boiling
mixtures (like alcohol-water) can be used for this purpose.
3.
Chemical constituents of the drug: The process
is unsuitable for thermolabile active constituents, e.g. enzymes, alkaloids,
anthraquinone derivatives, esters etc.
Examples:
Soxhlation process of extraction is used to
(i) extract of cantharidins from cantharides with
benzene
(ii) alkaloids from the seeds.
INFUSION
This method is used for those
drugs
i)
which are soft in nature so that water may penetrate
easily to the tissues and
ii) the
active constituents are water soluble.
Apparatus:
Coffee-pot or tea-pot is the
simplest form of apparatus used for preparing infusion. Sometimes special pots
known as infusion pots are used for
the preparation of infusions. It consists of a loose perforated shelf resting
on a projection near the top of the pot.
Method:
In coffee-pot or tea-pot:
i)
The drug is placed at the bottom of the pot. Water is
added and it is well stirred three or four times during the period of infusion.
ii) Infusion
can also be prepared by enclosing the drug in a muslin bag and then suspending
it just below the level of water in a beaker. Stirring is not required in this
case because the water slowly circulates due to the increase in specific
gravity of water near the drug.
In infusion pot:
The drug is placed on the perforated shelf. The pot is
filled with water and the perforated shelf is adjusted below the surface of
water.
* Final volume is not
adjusted.
There are two types of infusions:
1. Fresh
infusion, 2.
Concentrated infusion
Fresh infusions:
A fresh infusion is an aqueous
solution of active constituents of a vegetable drug prepared by the process of
infusion e.g. Fresh infusion of Quassia.
Coarse powder of drug is used in
the preparation of infusion. Water is used as menstruum.
Pharmacopoeia states that fresh
infusion should be used within 12 hours after its preparation because it gets
spoiled due to fungal or bacterial growth.
Concentrated infusions
Concentrated infusions differ
from fresh infusions in that the concentrated infusions are prepared by
maceration or percolation process and alcohol is used either as a menstruum or
as a preservative.
An infusion containing 20 - 25 %
alcohol can be stored for sufficiently long time.
e.g. Concentrated compound
infusion of chirata and
Concentrated compound infusion of
gentian.
DECOCTION
Decoction is the process in which
the water soluble and heat stable constituents of hard and woody crude drugs
are extracted out.
Water is used as menstruum and
the drug, cut in small pieces, is boiled with the menstruum for 10 to 15
minutes.
After boiling, the liquid is
cooled and filtered, more water is passed through the marc to produce the
required volume.
Adjustment to final volume is
necessary to get a uniform product.
A freshly prepared decoction
should only be dispensed and the same must be consumed within 24 hours.
At present no decoction is
official in IP or BP.
EXTRACT
Extracts are concentrated
preparations containing the active principles of vegetable or animal drugs. The
drugs are extracted with suitable solvents and the product is concentrated to
one of the three types of extract -
Liquid extract - of which 1 ml usually contains the active
constituents from 1 g of the drug.
Dry extract - obtained by completely removing the solvent under
reduced pressure.
Soft extract - obtained by evaporation to a plastic mass.
DIFFERENCE BETWEEN MACERATION AND
DECOCTION
Maceration
|
Decoction
|
1.
Menstruum may be water or hydroalcoholic solvents.
2.
The crude drug is macerated for 3-7 days.
3.
The drug is kept in contact with cold or warm
menstruum.
4.
After extraction the marc is expressed.
5.
Extra menstruum is not added to make up the required
volume.
6.
Alcohol acts as a preservative, hence it may be
dispensed after 24 hours also.
|
1.
Menstruum is water.
2.
Just 10 to 15 minutes is required to complete the
process.
3.
Boiling water is passed through the crude drug.
4.
After extraction the marc is not expressed.
5.
Extra menstruum is passed through the extracted drug
to make up the volume.
6.
A freshly prepared decoction should be taken within
24 hours because microorganisms may grow in aqueous medium.
|
INTRODUCTION AND CLASSIFICATION OF DOSAGE FORMS
DEFINITION OF DRUG
A drug may be defined as an agent,
intended for use in the diagnosis, mitigation, treatment, cure or prevention of
disease in man or in animals.
DOSAGE FORM
Drugs are rarely administered in
their original pure state. They are converted into suitable formulation which
are called dosage forms. Every
dosage form is a combination of the drug and other non-drug components.
The non-dug components are known as “additives”. The additives are used to
give a particular shape to the formulation, to increase its stability and also
to increase its palatability as well as to give more elegance to the
preparation.
Ques.
Why the drug should be converted into
dosage forms ?
Ans.
Transformation of drug into different dosage forms is done for the following
reasons:
1. To
protect the drug from oxidation (e.g. Vitamin C, Ferrous sulfate), hydrolysis
(aspirin) and reduction. e.g. coated tablets, sealed ampoules.
2. To
protect the drug from destructive effect of gastric juice (HCl) of the stomach
after oral administration e.g. enteric coated tablets.
3. To
provide a safe and convenient delivery of accurate dosage.
4. to
conceal the bitter (e.g. chloramphenicol), salty or obnoxious taste or odor of
a drug substance e.g. capsules, coated tablets and flavored syrups etc.
5. To
provide for the optimum drug action through inhalation therapy. e.g. inhalation
aerosols and inhalants.
6. To
provide for the drug into one of the body-cavities e.g. rectal suppositories.
7. To
provide for the maximum drug action from topical administration sites. e.g.
creams, ointments, ophthalmic preparations and E.N.T. (ear, nose and throat)
preparation.
8. To
provide sustained release action through controlled release mechanism. e.g.
sustained release tablets, capsules and suspensions.
9. To
provide liquid dosage form of the drugs soluble in a suitable vehicle e.g.
solutions.
CLASSIFICATION OF DOSAGE FORMS
 |
Route of administration
|
Dosage forms
|
Oral
|
Powders, tablets, capsules,
solutions, emulsions, syps, elixirs, magmas, gels, cachets, pills.
|
Parenteral
|
Solutions, suspensions, emulsions.
|
Transdermal
|
Ointments, creams, powders, pastes,
lotions, plaster
|
Rectal
|
Suppositories, tablets, ointments,
creams, douches, foams.
|
Urethral
|
suppositories
|
Sublingual
|
Lozenges, tablets
|
Intranasal
|
Solutions, sprays, inhalations.
|
Conjunctival
|
Ointments
|
Intra-ocular
|
Solutions
|
Intra-respiratory
|
Aerosols
|
Classification
according to physical state:
DOSAGE FORMS
SOLID
|
SEMISOLID
|
LIQUID
|
GAS
|
MISCELLANEOUS
|
|
Cachets
Capsules
Powders
Insufflations
Dentrifices
Effervescent granules
Lozenges
Pessaries
Tablets
Suppositories
|
Creams
Jellies
Ointments
Pastes
Ophthalmic ointments
|
Applications
Aromatic water
Collodion
Draught
Ear drops
eye drops
Nasal drops
Elixirs
Mixtures
Emulsions
Suspensions
Enemas
Gargles
|
Gels
injections
Irrigations
Linctuses
Liniments
Lotions
Mouthwashes
Spirits
Sprays
Syrups
Tinctures
Paints
|
Aerosols
inhalation
|
Transdermal drug delivery systems
Sustained release drug delivery
system
Ophthalmic drug delivery systems.
Implants
|
SOLID DOSAGE FORMS
 |
CACHETS
Cachets consists of a dry powder
enclosed in a shell. The shell is prepared from a mixture of rice flour and
water by moulding into suitable shape and then dried.
Two types or cachets are there: (i)
Wet seal and (ii) Dry seal cachet.
Use:
They are used for administering
the drug with unpleasant taste and a large dose. Before administration, a
cachet should be immersed in water for
few seconds and then placed on the tongue and swallowed with water.
CAPSULES
Capsule are the solid unit dosage form of medicament in
which the drug or drugs are enclosed in a practically tasteless, hard or soft
soluble container of shell made up of gelatin.
Hard gelatin capsules are made up of two cylindrical
halves, one slightly larger in diameter but shorter in length known as cap
and the other slightly shorter in diameter but longer in length known as base.
Soft gelatin capsules are flexible in nature.
They may be spherical, ovod cylindrical or tubes. The small spherical capsules
are also known as ‘pearls’. soft gelatin capsules are used to enclose solids,
semisolids or liquids.
For oral administration the capsule is placed on the tongue
and swallowed with a drink of water.
DUSTING POWDER
These are meant for external application on to the skin and
are generally applied in a very fine state of subdivision to avoid local
irritation.
Dusting powders are of two types:
(i) Medical and (ii) Surgical Dusting powder
Medical dusting powders are mainly used for
superficial skin conditions and for antiseptics, antipruritic, astringent,
antiperspirant, absorbent, protective and lubricant purposes.
e.g. dicophane
dusting powder
zinc and
salicylic acid dusting powder
zinc,
starch and talc dusting powder.
Surgical dusting powders are used in body cavities,
and also on major wounds as a result of burns and umbilical cords of infants.
Surgical dusting powders must be sterilized before their use.
e.g. Neosporin powder.
INSUFFLATIONS
These are finely divided powders meant for introduction into
the body cavities such as ears, nose, tooth sockets and vagina with the help of
an apparatus known as ‘insufflator’. Insufflator sprays the powder into stream
of finely divided particles all over the site of application.
Use: The
insufflations are used to produce a local effect, as in the treatment of ear,
nose and throat infection with antibiotics or to produce a systemic effect from
a drug that is destroyed in the gastrointestinal tract.
DENTRIFICES (Tooth Powders)
Dentrifices are preparations which are generally used with
the help of tooth bush for cleansing the surfaces of the teeth. They are
available in the form of fine powders and pastes.
They contain
1.
a suitable detergent of soap
2.
some abrasive substance like calcium sulfate, magnesium
carbonate, sodium carbonate in fine powder.
3.
sweetening agent e.g. saccharin sodium
4.
a suitable flavor e.g. peppermint oil, clove oil.
EFFERVESCENT GRANULES
The effervescent granules are specially prepared granular
solid dosage form, meant for oral intake. They contain a medicament mixed with
citric acid, tartaric acid and sodium bicarbonate. Sometimes saccharin or
sucrose may be added as a sweetening agent. In water citric acid and tartaric
acid reacts with sodium bicarbonate and produce carbon dioxide that bubbles out
rapidly. This CO2 produces the effervescence.
Medicaments: Often inorganic salts containing water
of crystallization are incorporated. e.g. magnesium and sodium sulfates, sodium
phosphate and lithium citrate.
Use: Before
administration, the desired quantity is dissolved in water, the acid and
bicarbonate react together producing effervescence. The carbonated water
produced from the release of carbon dioxide serves to mask the bitter and
saline taste of drugs.
More over carbondioxide stimulates the flow of gastric juice
and helps absorption of medicament.
LOZENGES
Lozenges are solid dosage form of medicaments which are
meant for slow dissolution in the mouth. Along with medicament they contain a
sweetening agent, flavouring agent and a strong binding agent.
They may be prepared either by moulding or by compression.
Examples are compound bismuth lozenges, liquorice lozenges.
POWDERS
Powders are solid dosage form of medicament meant for
internal and external use. The powders meant for internal use are known as oral
powders whereas those meant for external use are known as dusting powders.
When the powders are dispensed in large quantities in a
container and the patient is asked to measure a specified quantity as a dose
then these powders are known as bulk powders.
1. Bulk powder for internal use;
e.g.
Compound sodium chloride and
dextrose oral powder.
Compound
rhubarb oral powder
2. Bulk powder for external use;
e.g. Snuffs
Talc
dusting powders
Tooth
powder.
TABLETS
Tablets are unit solid dosage form of medicament or
medicament with or without suitable diluents. They are prepared usually by
compression. Tablets are generally meant for oral administration but may be
used by other routes of administration. e.g.
aminophylline tablets, paracetamol
tablets, antacid tablets etc.
SUPPOSITORIES
Suppositories are special shaped solid dosage form of
medicament for insertion into body cavities other than mouth. These products
are so formulated that after insertion, they will either melt of dissolve in
the cavity fluids to release the drug.
Suppositories vary in shapes, sizes and weights. General
suppositories from 1 to 2 gm are prepared with either cocoabutter or glecero-
gelatin base.
e.g. aminophylline
suppositories, glecerol suppositories.
PESSARIES
Pessaries are solid unit dosage form of medicament meant
for introduction into vagina. The bases used for the manufacture of pessaries
are such that at room temperature they retain the original shape but when
inserted into the body cavity either it melts or dissolve in the cavity fluids
to release the medicament.
They may be prepared either by moulding or by compression.
e.g. lactic acid pessaries, nystatin pessaries
SEMISOLID DOSAGE FORMS
CREAMS
Creams are viscous semisolid emulsions intended for
application to the skin i.e. for external use.
Creams are of two types, aqueous creams and oily
creams. In case of aqueous creams the emulsions are oil-in-water type and in
case of oily creams emulsions are of water-in-oil type.
JELLIES
Jellies are transparent or non-greasy semisolid preparations
meant for external application to the skin or mucous membrane. They are used
for medication or lubrication purposes.
They are used for lubrication of catheters, surgical gloves
and rectal thermometers.
The gelling agents may be gelatin, or a carbohydrate such as
starch, tragacanth, sodium alginate or cellulose derivative.
OINTMENTS
Ointments are the soft semisolid, greasy preparations meant
for external application onto the skin or mucous membrane (rectum and nasal
mucosa).
They usually contain a medicament dissolved, suspended or
emulsified in the base.
Ointments are used for their emollient and protective action
to the skin.
e.g. compound
benzoic acid ointment, cetrimide
emulsifying ointment
PASTES
Pastes are semisolid preparations meant for external
application to the skin. they generally contain large amount of finely
powdered solids such as starch, zinc oxide, calcium carbonate etc.
They provide a protective coating over the areas to which
they are applied.
The base may be anhydrous (liquid or soft paraffin) or
water-soluble (glycerol or a mucilage). Their stiffness make them useful as
protective coatings.
e.g. magnesium
sulfate paste, zinc and
coal-tar paste
OPHTHALMIC OINTMENTS
Ophthalmic ointments are meant for application to the eye.
They should be sterile and free from irritation. They should be packed in
sterile containers that should keep the preparation sterile until whole of it
is used up.
e.g atropine
eye ointment, chloromycetin eye ointments
LIQUID DOSAGE FORMS
APPLICATIONS
Applications are liquid or viscous preparations intended for
application to the skin. usually, they are suspensions or emulsions.
Most of the official preparations contain paraciticides and
are intended for only a limited number of applications.
They should be dispensed in colored fluted bottles in order
to distinguish them from preparations meant for internal use. The container
should be labeled “FOR EXTERNAL USE ONLY”.
Examples of applications are: Calamine application compound
B.P.C., Dicophane application B.P.C.
AROMATIC WATERS
Aromatic waters are also known as medicated waters. They are
dilute , ususlly satureated, aqueous solutions of volatile oils (e.g.
peppermint oil, cinnamon oil) or volatile substances (e.g. camphor). Some of
them have a mild therapeutic action but mainly they are used as flavouring
agemts in preparations meant for internal use.
COLLODIONS
Collodions are the liquid preparations meant for external
application on to the skin. Use: They are convenient applications for
small cuts and abrasions and are also used when a prolonged contact between the
skin and the medicament is required.
Preparation: The vehicle used is volatile and
evaporates on application to the skin leaving a flexible protective film
covering at the site of application. They are applied with a brush or rod.
Composition: Flexible collodion contains pyroxillon
(nitrocellulose), castor oil and alcohol in solvent ether. Alcohol and solvent
ether are used as vehicle, pyroxillon as film producing agent and castor oil
gives flexibility.
The unmedicated collodions are useful for protecting small
cuts and abrasions, while the medicated form provide prolonged contact between
the skin and the medicament.
DRAUGHT
A draught is a liquid oral preparation taken as a single dose
(10 to 15 ml). If several doses are prescribed, each dose is dispensed in
separate container.
e.g. male fern extract draught and paraldehyde draught.
EAR DROP
Ear drops are liquid preparations in which the drug pr drugs
are dissolved or suspended I a suitable vehicle, like water, dilute alcohol,
glycerin or propylene glycol and are intended for instillation into the ear
with a dropper.
They are generally used for cleansing the ear, drying
weeping surfaces, softening the wax and for treating the mild infections.
The containers should be labelled “FOR EXTERNAL USE ONLY”.
e.g. Hydrogen
peroxide ear drops, Phenol ear drops etc.
EYE DROPS
Eye drops are sterile aqueous or oily solutions or
suspensions for instillation into the eye. They are usually applied in the
space between the eye-ball and eyelids or o to the corneal surface.
The main requirements of eye drops are: they should be
sterile, usually isotonic, buffered and free from foreign particles to avoid
irritation to the eye. They usually have antiseptic, anaesthetic,
anti-inflammatory, mydriatic or miotic properties.
Eye drops are dispensed in glass or suitable plastic
containers with dropper or narrow nozzle.
e.g. chloramphenicol,
atropine eye drop, pilocarpine eye drop.
ELIXIRS
Elixirs are clear, pleasantly flavored, sweetened
hydroalcoholic liquid preparations for oral administration.
The main ingredients of elixirs are ethanol and water but
glycerin, sorbitol, propylene glycol, flavoring
agents, sugar and preservatives may be incorporated to the preparation.
The elixir may be medicated or non-medicated. The medicated
elixirs usually contain very potent drugs such as, antibiotics, antihistaminics
and sedatives.
The non-medicated elixirs are used as flavors and vehicles.
e.g. chloramphenicol
elixir, diphenhydramine elixir, paracetamol elixir, paediatric (for children)
piperazine
citrate elixir etc.
Some unstable drugs are dispensed as dry elixirs.
Before dispensing, ir is dissolved in a suitable vehicle.
EMULSIONS
Emulsions are the biphasic liquid dosage form of medicaments
in which two immiscible liquids (generally one of which is water and the other
is some lipid or oil) are made miscible by the addition of a third substance
known as emulgent or emulsifying agent.
Emulsions are of two types (a) oil-in-water (o/w), (b)
water-in-oil (w/o).
O/w types of emulsions are generally for oral administration
where as the w/o type of emulsion is generally for application onto the skin.
Emulsion should be supplied in wide mouthed containers
labeled with “SHAKE THE BOTTLE BEFORE USE” message.
e.g. Castor oil
emulsion, Liquid paraffin emulsion, Liquid paraffin and phenolphthalein
emulsion etc.
ENEMAS
Enemas are aqueous, oily solutions or suspensions intended
for introduction into the rectum for their purgative, sedative, anthelmintic
(killing the worms), anti-inflammatory effects. They may be used for X-ray
examination of the lower intestine.
Commonly used drugs in solution form which act as cleansing
enemas include isotonic solution of sodium chloride, sodium bicarbonate, sodium
phosphate, magnesium sulfate, soap and a combination of these substances.
The other drugs in the form of enemas include olive oil,
arachis oil, chloralhydrate, paraldehyde, alum, tannic acid, barium sulfate
etc.
Usually solutions in volume of 500 ml to 1000 ml, depending
on the age and condition of the patient, are introduced as enema.
Commercially available concentrated enemas are introduced in
small volume of 100 to 200 ml.
Large volume enemas should be warmed to body temperature
before administration.
e.g. Paraldehyde
enema, Soap enema etc.
GARGLES
Gargles are aqueous solutions used for the prevention or
treatment of throat infections. Usually they are concentrated solutions and
should be diluted with warm water before use. In using the gargles they are
brought into intimate contact with the mucous membrane of the throat and are
allowed to remain there for a few moments after which they are thrown out of
the mouth.
Gargles should be dispensed in white fluted bottles.
e.g. aspirin gargle.
GELS
Gels are aqueous colloidal suspensions of the hydrated forms
of insoluble inorganic drugs.
e.g. aluminum
hydroxide gel, milk of magnesia, aluminum phosphate gel
INJECTIONS
Injections are the sterile liquid preparations containing
one or more medicaments dissolved or suspended in a suitable vehicle and are
meant for introduction into the body tissues by means of an injection needle
under or through, on or more layers of skin or mucous membrane.
e.g. ampicillin
injection, dextrose intraveous injection, gentamicin injection
IRRIGATIONS
These are solutions containing medicaments used o treat
infections of the bladder, vagina and nose. These are introduced into the
cavities by means of a soft rubber tube known as catheter. They are generally
used as antiseptics, anti-inflammatory or cleansing solutions.
LINCTUSES
Linctuses are viscous, liquid, oral preparations that are
usually prescribed for the relief of cough. They are simple solutions or
admixtures containing a high proportion of syrup and sometimes, glycerin which
has sweet taste and also have a demulcent effect on the mucous membranes of the
throat.
The dose is small (5 ml) and to have prolonged action,
should be sipped slowly and swallowed.
LINIMENTS
Liniments are liquid or semisolid preparations for external
application to the skin.
They may be alcoholic or oily solutions or emulsions.
Most are massaged onto the skin (counter irritants or
stimulant type). They should never be applied onto broken skin, because they
will be very irritating.
The label should carry the warnings:
“NOT TO BE APPLIED TO WOUNDS OR
BROKEN SKIN”
and “FOR
EXTERNAL USE ONLY”
e.g. Soap
Liniment BPC, Camphor Liniment BPC,, Methyl salicylate Liniment BPC
LOTIONS
Lotions are liquid solutions or suspensions meant for
external application to the skin but without friction.
They usually contain alcohol and glycerin, because alcohol
hastens drying and produces cooling sensation whereas glycerin keeps the skin
moist for a sufficiently long time.
About half of the official lotions are solutions. Their main
ingredients are simple salts.
e.g. copper
sulfate, zinc sulfate and lead subacetate which are soluble in water.
Salicylic
acid for which alcohol is the solvent
Lead
lotions, for sprains and bruises
Zinc
sulfate and salicylic acid lotion, for ulcers
Salicylic
acid lotion for dandruff
Calamine
lotion
N.B. Copper and zinc sulfate are astrigent while
Salicylic acid is keratolytic,
bacteriostatic and fungicidal.
All lotions are labeled, “FOR EXTERNAL USE ONLY”.
EXTRACTION METHODS
|
EXAMPLES
|
A. MACERATION
i) Simple maceration
ii) Maceration
of unorganized drug / Maceration with adjustment
iii) Multiple Maceration
a)
Double maceration
b)
Triple maceration
B. PERCOLATION
i) Simple percolation
ii) Reserved percolation
iii) Continuous hot percolation / Soxhlation
C. INFUSION
i) Fresh infusion
ii) Concentrated infusion
D. DECOCTION
|
i)
Tincture of Orange
ii)
Tincture of Lemon
iii) Tincture
of Squill.
i)
Tincture of Tolu Balsam
ii)
Compound Tincture of Benzoin
i)
Concentrated infusion of orange.
ii)
Concentrated infusion of chirata
iii) Concentrated
infusion of gentian
i)
Concentrated infusion of Quassia
ii)
Concentrated infusion of Senna
i)
Tincture of Belladonna
ii)
Compound tincture of cardamom
iii) Strong
tincture of ginger etc.
Liquid extract of Liquorice
i)
Cantharidin from cantharides
ii)
Alkaloids from seeds
Fresh infusion of Quassia
i)
Concentrated compound infusion of chirata
ii) Concentrated
compound infusion of gentian
No official preparations in IP or BP.
|
Comparison between extraction methods:
Extraction method
|
Time for extraction
|
Temperature
|
Characteristics of the active
constituents
|
Maceration
Percolation
Digestion
Infusion
Decoction
|
3-7 days
24 hours
Few days
Short period
15 mins
|
Room temp
Room temp
Moderately high
Cold or boiling
water
Boiling water
|
·
Soluble in the menstruum
·
Heat stable / unstable
·
Soluble in the menstruum
·
Heat stable / unstable
·
Heat stable
·
Readily soluble
·
Water soluble
·
Heat stable
|
QUESTIONS FOR FINAL EXAM
Ques.1. Describe the percolation process in details with a schematic
diagram of a typical percolator. [12]
Ans:- Simple percolation process.
Ques 2 What is reserved percolation? [4]
Ques.3. Short notes on Maceration and Decoction. [ 8] Ans:- Write
the difference between Maceration and Decoction.
Ques. 4. Short note on Soxhlet extractor with diagram. [ 8]
Ques.5. How does the method of preparation vary for concentrated
infusion and fresh infusion. [3]
Ans:- See ‘Infusion’.
Ques. 6. Difference between infusion and decoction? [2] Ans:- Write yourself.
Ques7. Classify dosage forms.
Ans. Classification according to physical state.
Ques.8. Classify dosage form according to route of administration.