GALENICALS....

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.
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