Short notes on the Classification of Dosage Form

A pharmacist is required to dispense a wide range of preparations. Some of them may require compounding and others dispensed in manufacturer's package or packed by the pharmacist according to the quantity required. However it is desirable that a pharmacist is familiar with all varieties of preparations that he handles. A classification of preparations along with a brief description is given. Preparations that may require compounding are underlined.

Definitions of Some dosage Forms

Aerosols:

Aerosols are suspensions of fine, solid or liquid particles in a gas. This preparation is also known as pressurized preparation. These are dosage forms for spraying in a solution, suspension or emulsion form with an atomizer device or nebulisers. Aerosols are packed in pressurized containers with suitable propellants that provide a steady stream of the liquid. They are most popular in the treatment of asthma or respiratory tract infection and skin conditions.

Applications:

These are fluid or semi-fluid preparations intended for application to the skin. These formulations are generally in the form of emulsion and suspension. Some official examples are used as antiparasites and also in other skin diseases.

Cachets:

Cachets are disc or cylinder shaped devices made from rice paper and consist of a lower and upper part, the latter having a slightly broader flange. Medication of disagreeable taste is enclosed between the two halves and sealed.

Capsules:

These are similar to cylindrical cachets and are available in different sizes. The material is however gelatin, hard or flexible (hard or soft gelatin capsules).

Collodians:

Fluid preparations for external use in the form of collodians contain substances dissolved in a volatile solvent which, after evaporation, leaves a thin film of the material on the surface.

Creams:

Highly viscous oil-in-water or water-in-oil emulsions meant for external application are considered as creams. Medicament may also be incorporated in them.

Draughts:

Liquid oral preparations packed as a single dose in separate containers and in large volumes are known as draught.

Dusting Powders:

This form of medication comprises of extremely fine particles to be dusted on the affected part.

Elixirs:

These are sweetened, clear and coloured, aromatic, hydroalcoholic liquids.

Emulsions:

Emulsions are mixtures of two immiscible liquids in which one phase is dispersed into the other in the form of minute globules. An emulsifying agent is employed to bring about emulsification. Usually unpalatable oils may be conveniently administered as emulsions dispersed in water.

Ear drops:

Solutions of drugs meant for dropping in the ears are classified as ear drops.

Enemas:

Drugs in solution or in dispersed form meant for rectal administration are called enemas.

Gargles:

Aqueous solutions employed for local action in the throat are called gargles. They may be diluted with luke-warm water before use.

Gels:

Insoluble substances presented as suspension of their colloidal state in a hydrated form are known as gels.

Granules:

These are free flowing, dry conglomerates of particles ranging from 1 to 5 mm in diameter. The medicament and the excipients are rendered to a cohesive mass with a suitable moistening agent and the mass is pressed through a sieve of required granule size and dried.

Inhalations:

Inhalations are the preparations meant for relieving congestion of the throat. These preparations are either volatile and inhaled directly, or contain volatile substances which can be inhaled by adding the preparation to hot water.

Insufflations:

Insufflations, commonly known as snuffs also, provide a medicament intimately mixed with a dusting powder to be deeply inhaled or blown into body cavities by an insufflator.

Irrigations:

These preparations are used as antiseptics for washing the urinary bladder or vagina, the solution being introduced through a soft tube.

Jellies:

Jellies are non-greasy semi-solid preparations containing a high proportion of gelatin, gum or starch.

Lozenges:

The medicament, sugar and gum are made into a solid form for local action and slow release of the drug meant for the mouth and the throat.

Liniments:

Emulsions, viscous, oily or free flowing solutions of drug in alcohol meant for application to the skin usually by rubbing are called liniments.

Lotions: These are preparations in solution or suspension form to be applied to the affected part without friction. The lotions may be applied as such or with the support of a dressing material.

Mixtures:

Solutions and suspensions meant for oral use are classified as mixtures. The vehicle is usually water and their stability is limited from a few days upto a few weeks.

Mouth washes:

Mouth washes are liquid preparations for treating mouth infections or providing a freshening feeling. They are usually diluted before use.

Nasal Drops:

Solution of drugs meant for instilling in the nasal cavity with the aid of a dropper are considered as nasal drop.

Ointments:

These are semi-solids meant for external use. The medicament is incorporated in the base usually comprising of greasy substances.

Pastilles:

The drug along with gelatin and glycerin is converted into a solid form for slow dissolution in the mouth.

Pills:

Pills are spherical dosage forms containing the drug and excipients. Pills have now been almost completely replaced by capsules and tablets. As dosage form pills are very popular in J Ayurvedic medicine and are known as vati.

Powders:

The medicament with or without excipient in fine state of subdivision is supplied in either bulk or individually wrapped in a paper.

Pessaries:

The medicament is either compressed in a suitable shape or moulded with the help of a base so that it is released when inserted into vagina by solution or melting.

Pastes:

Pastes contain a very high proportion of the solid medicament in relatively small proportion of the base, meant for external application.

Poultices:

These are thick and pasty preparations. Due to good heat retention property, the) may be applied on a dressing while hot and bandaged on to the affected part to relieve inflammation.

Paints:

Solutions in viscous vehicles or suspensions that are meant to be applied to the skin or mucus with a soft device such as brush or cotton are called paints.

Solution Tablets:

These are tablets designed to dissolve quickly in water. After dissolution, the solution can be applied to the skin or mucous.

Syrups:

These are concentrated solutions of sucrose or any other sugars. Syrups are less commonly prescribed as such except cough syrups but are very often prescribed as sweetening and flavouring vehicles.

Sprays:

Drugs dissolved in alcoholic or glycerin media and sprayed in the form of fine droplets to the mucous with the help of a spraying device are called sprays.

Suppositories:

These are semi-solid to solid moulded preparations meant for insertion into the rectum. They resemble pessaries which are meant for vagina. The medication is incorporated in a suitable base that liquefies at the body temperature and releases the medicament. Some of the bases may dissolve in the rectum and release the medicament.

Tablets:

These are solid dosage forms in which the medicament is compressed in different shapes and sizes. They may be plain or coated. Tablets remain the most popular dosage form.