Extraction

“Extraction” may be defined as the treatment of the plant or animal tissues with solvent,
whereby medicinally active constituents are dissolved, and most of the inert matter remains
undissolved. OR
Extraction is the method of removing active constituents from a solid or liquid by means of
liquid solvent.
•Menstruum- The solvent used for extraction is known as Menstruum.
•Marc- The inert insoluble material that remains after extraction is called Marc.
•Galenical- A medicine prepared by extracting one or more active constituents of a plant.
The various Processes used for Extraction are-
1. Infusion 2. Decoction 3. Maceration
4. Percolation 5. Digestion.
Solvents used in Extraction processes- The various solvents is employed in extraction process
which is capable of penetrating the tissues of the drug and dissolve the active principles
contained in its cell.
Solvents used in Extraction Processes:-
In extraction process a solvent is employed which is capable of penetrating the tissues of the
drug and dissolve the active principles contained in its cell.
The various solvents used are as under-
1. Water:- Water is a solvent for protein, colouring matter, gums, glycosides, sugars,
alkaloidal salts, enzymes, many organic acids and most of the organic salts.
Waxes, fats, fixed oils and most alkaloids are insoluble in water.
2. Alcohol:- Alcohol is a solvent of alkaloids, alkaloidal salts, glycosides, volatile oils and
resins.
Alcohol also dissolve many forms of colouring matter, tannins, many organic acids and
salts.
Alcohol does not dissolve albuminous matter, gums, waxes, fats, fixed oils and sugar.
3. Ether:- It is used for the extraction of oils, fats and most alkaloidal bases.
4. Chloroform:- Useful in extraction of compounds such as terpenoids, flavonoids, fats
and oils.
5. Glycerin:- This is a good solvent for tannins. It reduce the oxidation of phlobatannins to
insoluble phlobaphenes.
 Process used for Extraction
Infusion
• It consist of pouring water over the drugs
↓
• Then allowing it to keep in contact with water for the stated period, usually 15
minutes, with occasional stirring
↓
• Finally filtering off the liquid.
• The marc is not pressed.
Apparatus:-
• Coffee pot or Teapot is the simplest form of apparatus used for preparing infusion.
• Drug is placed at the bottom of the pot.
• Water is added and it is well stirred 3 or 4 times.
• Infusion can also be prepared by enclosing the drug in a muslin bag and then
suspending it just below the level of the water in a beaker.
• Stirring is not required because water slowly circulate due to increase in specific
gravity of water near the drug.
• When water comes in contact with the drug, it dissolve active constituents and
become heavier.
•Heavier layer come down and their place is taken fresh water.
• As a result, there is slow circulation of water and hence stirring is not required.
• Special pots known as “infusion pot” used for preparation of infusion.

There are two types of infusion:-

1. Fresh Infusion
2. Concentrated infusion.
Fresh Infusion:-
• 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 because it has more penetration power and dissolve
the active constituents.
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 Infusion:-
• It is prepared by double or triple maceration process.
• Concentrated infusions are 8 times stronger than fresh infusion.
• Alcohol in the concentration of 20-25% is used as menstruum.
• Hence these preparation can be stored for longer period due to preservatives action
of alcohol.
e.g. Concentrated infusion of Quassia and concentrated compound infusion of Chirata.

Decoction
Drug is boiled with water for stated period usually 10 minutes.
↓
After boiling, the liquid is strained and water is passed through the content of the
strainer to make the required volume.
This process is mainly used for vegetables drugs of hard and woody nature having
thermostable water soluble constituents.

Maceration
Various types of maceration process:-
1. A Process for tinctures made from organised drug e.g. roots, stems, leaves etc. This
process is called ‘Simple Maceration’.
2. A process for tinctures made from unorganised drugs such as oleo gum resins. This
process is known as ‘Maceration with Adjustment’.
3. Process for concentrated preparations which include both ‘Double Maceration’ and
‘Triple Maceration’.
Maceration process for tincture made from organised drugs (Simple Maceration)
Apparatus-
• A wide mouthed bottle or any other container which can be well stoppered is used
for maceration process.
• A closed container is essential to prevent the evaporation of menstruum which is
mostly concentrated alcohol.
• No adjustment in volume is made.
Method:-
•Drug is placed with the whole of the menstruum in a closed vessel for seven days.
• During is period shaking is done occasionally.
• After seven days, the liquid is strained and marc is pressed.
 • It is then filtered to make a clear liquid.
• The final volume is not adjusted.
Example:-
1. Tincture of Orange.
2. Tincture of Lemon.
3. Tincture of Squill.

Maceration Process for Unorganised drugs or Maceration with adjustment-

Method-
• Unorganised drug is placed with 4/5th of the menstruum in a closed vessel for period of 2-7
days.
• Shaking is done occasionally.
• After stated period, liquid is filtered and final volume is made up by passing remaining 1/5th
of the menstruum.
• The marc is not pressed.
Example:-
1. Tincture of tolu.
2. Compound tincture of benzoin.

Maceration Process for Concentrated Preparations or Multiple Maceration Process

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 into
three parts in triple maceration process.
Double Maceration Process:-
• 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.
• The quantity of menstruum required for two macerations are calculated as-
1. Volume of menstruum required for first maceration=
Total vol. of menstruum − vol. to be retained by drug + vol. to be retained by drug
2
2. Volume of menstruum required second maceration=
Total vol. of menstruum − vol. of menstruum used in first maceration
• In double maceration process, whole of the drug is macerated for 48 hours with the
quantity of menstruum required for first maceration.
• Strain the liquid and press the marc.
• Mix the liquid obtained from two maceration and allow it to stand for 14 days and then
filter.
Example-
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 is used for each
maceration.
The quantity of menstruum required for three maceration is calculated as follows-
1. Vol. of menstruum required for first maceration
Total vol. of menstruum – Vol. to be retained by the drug + Vol. to be retained by the drug
3
2. Vol. of menstruum required 2nd and 3rd maceration
Total vol. of menstruum – Vol. of menstruum used in 1st maceration
2
• The whole of the drug is macerated for one hour with a part of menstruum required
for first maceration and strained.
• Macerate again for one hour with part of menstruum required second maceration
and strained.
• Macerate again for one hour with part of menstruum required for third maceration
and strained.
• Press the marc lightly.
•Then combine the liquid obtained from second and third maceration and evaporate it
to specified extend.
• Mix it with liquid obtained from first maceration.
• Add alcohol 90% equal to 1/4th of the volume of the finished product.
• Adjust volume with water.
• Allow it to stand for 14 days and filter.
Example-
1. Concentrated infusion of Quassia.
2. Liquid extract of Senna.
 Percolation Process
The various percolation processes used for the extraction of drugs are-
1. Simple Percolation or percolation process for tinctures.
2. Percolation processes for concentrated preparations such as:
a) Reserve percolation process
b) Modified percolation process
3. Continuous hot percolation or Soxhelation.
Apparatus:-
1. Conical percolator
2. Cylindrical percolator
3. Steam jacketed percolator
Method:-
Simple percolation process used for the preparation of tincture.
• There are three stages in the official method for the preparation of tincture-
a) Imbibition
b) Maceration
c) Percolation
Imbibition:-
• The powdered drug is moistened with sufficient quantity of menstruum and allowed to
stand for 4 hours in a closed vessel.
• Pack the moistened drug into percolators and add sufficient quantity of menstruum to
saturate the material.
• When liquid starts coming out from outlet of percolators the outlet is closed.
• Then the sufficient quantity of menstruum is added in order to leave a layer above the
drug.
Maceration:-
• The moistened drug is left in contact with menstruum for 24 hours.
• During this period, the menstruum dissolves the active constituents of the drug and
becomes almost saturated with it.
Percolation:-
• It consist of downward displacement of saturated solution formed in maceration and
extraction of the remaining active constituents present in the drug by slow passage of the
menstruum through the column of the drug.
• After collecting 3/4th of the required volume of the finished product or when the drug is
completely exhausted, the marc is pressed.
• Mix the expressed liquid with percolate.
• Add sufficient quantity of menstruum to produce required volume and then filter.

Steps involving maceration:-

• The powdered drug is moistened with some of the menstruum and set aside for 4 hours.
The moistened drug is packed in the percolator uniformly.
• A filter paper is then placed on the packed drug. A layer of sand is then placed over the
filter paper to prevent the disturbance of the top layers of the drug when the menstruum is
added.
• Then the required quantity of menstruum is added over the packed column of the drug to
form a layer above it, it is then set aside for 24 hours.
• Percolation is then commenced and 85 percent portion of the percolate is collected. The
marc from the percolator is collected in a cloth, pressed and expressed liquid is collected
which is then mixed with 85 percent of the percolate already collected.
• It is then adjusted to the required volume with more menstruum, finally it is filtered.
Examples:-
Strong tincture of Ginger.
Tincture of Digitalis.
Compound tincture of Cardamom.
Tincture of Belladona