Classification of Dosage Form

Dosage forms are the safe, effective, and stable terms in which medication will be delivered into the body. Dosage forms are essentially pharmaceutical product which is marketed for use typically involving a mixture of active drug components and excipients (non-drug components). These dosage forms are classified in several ways as mentioned below by which drug molecules are delivered to the site of action.

1. Form wise:

  1. Solid dosage form
  2. Liquid dosage form
  3. Semi-solid dosage form

2. Route wise:

  1. Oral dosage form
  2. Topical dosage form
  3. Parenteral dosage form

3. Release rate:

  1. Sustained release
  2. Prolonged-release
  3. Controlled release
  4. Targeted drug delivery
Classification of Dosage Form
Fig: Solid Dosage Form
Classification of Dosage Form
Fig: Liquid dosage form
Classification of Dosage Form
Fig: Semi-solid dosage form

1. Aromatic water: They are saturated aqueous solutions of volatile oils or other aromatic or volatile substances. e.g. Camphor water concentrated Peppermint water.

Mainly used as a flavoring agent. They are prepared by:

  1. Distillation. e.g. Strong rose water, orange flower water.
  2. Solution method. e.g. Dill water, pepper water, camphor water.
  3. Alternate solution method. e.g. Volatile oil is thoroughly mixed with an inert adsorptive agent (talc, kieselguhr), then one liter of purified water is added and agitated for 10 minutes. The solution is filtered until a clear filtrate is obtained. e.g. Concentrated peppermint water.

2. Cachets: They are solid dosage forms meant for oral administration of nauseous and disagreeable drug substances. These are molded from rice paper, a material made by pouring a mixture of rice flour and water between two hot polished revolving cylinders upon which water evaporates and a sheet of the wafer is formed. In the filling of the cachet, the medicament is placed between two pieces of a cachet which are then either wet sealed or dry sealed. Cachets are made in a variety of sizes holding from 0.2 to 2 grams of powder of medium density. Before administration, they are softened by immersion in water for a few seconds and then taken with a draught of water.

3. Tinctures: Tinctures are sweet viscous liquid oral preparation containing medical substances which have demulcent, sedative, or expectorant preparation. The simple solution or administrations containing a high proportion of syrup and glycerin have a demulcent effect on the mucous membrane of the throat e.g. Codeine tincture. They are an alcoholic or hydroalcoholic solution of chemicals or soluble constituents of crude drugs. e.g., orange tinctures, ipecacuanha tinctures, cardamom tinctures. The tincture contains 20-90% alcohol and spirits, containing volatile substances only.

They are prepared by

  1. Simple dilution of stronger preparation
  2. Maceration
  3. Percolation

4. Spirits: Spirits are an alcoholic or hydroalcoholic solution of volatile oils that are used internally for their medicinal values and flavoring agent. Spirit may also be applied externally or used by inhalation. e.g., Aromatic spirit of ammonia. They are prepared by

  1. Simple dissolution
  2. Maceration
  3. Chemical reaction
  4. Distillation

5. Proof spirits: They are defined as a mixture of alcohol and water which is 51°F weight 12/13th of an equal volume of water. The strength of alcoholic preparation is medicated by degrees, overproof (o/p), or under proof (u/p). Any alcoholic solution which contains 57.1% V/v alcohol is a proof spirit and said to be 100 proof.

6. Elixirs: Elixirs are clean liquid; oral alcoholic preparation contains potent and nauseous drugs which are plenty flavored and usually attractive colored. They are more stables than a mixture.


  1. Non medicated elixir e.g. Compound benzaldehyde elixir.
  2. Medicated elixir e.g. Chlorpheniramine, Chloral hydrate

7. Syrups: Syrups are a concentration aqueous preparation of sugar or sugar substances with or without flavoring agent and medical substances.

  1. Medicated Syrup
  2. Flavored Syrup

Syrup IP is 66.7% w/w solution of sucrose whereas syrup USP is 85% w/v or 64.74% w/w solution of sucrose in purified water.

8. Droughts: Droughts are oral liquid preparation meant to take as a single dose. A single dose of the mixture is usually known as draught.

  1. Male fern drought
  2. Paraldehyde drought: oxidizes to acetic acid on storage leads to death.

9. Drops: Drops are liquid oral preparation of potent drugs or vitamin which are given in to original form without dilution.

10. Ear drops: They are liquid preparations meant for instillation into the ear. In these preparations, the drug is usually dissolved or suspended in a suitable solvent such as propylene glycol, polyethylene glycol, glycerol, alcohol, and water or a mixture of these. Aqueous vehicle is generally not preferred because the secretions in the ear are fatty and as such these do not mix with water.

11. Eye drops: They are aqueous and oily solutions or suspensions of one or more active ingredients for installation into the eye sac. These are sterile free from foreign particles and irritating effects. They contain auxiliary substances such as isotonicity agents, buffers, antioxidants, stabilizers, and preservatives.

Eye Drops
Fig. Eye Drops

They are Categorised into several various types:

  1. A liquid preparation for application to the surface of the eye. e.g., Eye drops, lotions.
  2. Semisolid dosage forms eg., Ointment, Cream, gels.
  3. Parenteral products for sub-conjunctival or Intraocular injection.
  4. Solid dosage form intended to be placed in contact with the surface of the eye.

12. Ointments: Ointments are semisolid preparation indented to adhere to the skin or certain mucous membranes. They are usually solutions or dispersions of one or more medicaments in non-aqueous bases. Ointment bases are often anhydrous and include fats, oils, and waxes of animal vegetable or mineral origin.

13. Eye Ointment: These are sterile semi-solid preparations of homogeneous appearance intended for application to the conjunctiva or margins of eyelids. They contain one or more active ingredients dissolved and dispersed in a suitable base like soft paraffin, liquid paraffin, and wool fat. They contain a suitable amount of antioxidants, stabilizers, and antimicrobial preservatives.

14. Gargles: Gargles are an aqueous solution used to prevent or treat the infection. They are usually available in concentrated form with direction for dilution with warm water before use. They are brought into intimate contact with the mucous membrane of the throat and are allowed to remain in contact with it for a few seconds before they are thrown out of the mouth. Phenol or thymol may be present in low concentrations which exert a mild anesthetic effect. KCI is included in gargle preparation for its weak astringent effect. Gargle differs from mouthwashes because they are a light medicated oral mixture that is to be diluted with water before use.

e.g. Phenol gargle, KCIO3 gargles.

15. Creams: Creams are viscous semisolids that are usually o/w emulsions (aqueous Creams) or w/o emulsions (oily creams). Creams are usually pseudoplastic and exhibit low yield values. The microstructure of o/w cream may comprise several phases, such as viscoelastic gel with fixed water, dispersed oil, free water, and crystalline material from fatty alcohol. The rigidity can be increased by incision of a higher concentration of agent which is usually admixture to acetyl and stearyl alcohol and a surfactant.

16. Gels: Gels are transparent or translucent semisolid or solid preparations, consisting of a solution of one or more active ingredients in suitable hydrophilic or hydrophobic bases. They are made with aid of a suitable gelling agent. Usually, gel exhibits pseudoplastic flow properties and those made with synthetic or semi-synthetic polymers with a high degree of the cross have relatively high yield value and low viscosity.

17 Pastes: They are semi-solid preparations for topical application that differ from similar products in containing higher proportions of finely divided medicaments. They are much stiffened than ointment and are used principally as absorbents, antiseptics properties or to smooth broken skin surfaces. Pastes usually consist of a finely ground insoluble powder dispersed in hydrocarbon or water-miscible bases. The bases used are liquid paraffin/glycerol. They show dilatant properties and have a high yield value.

18. Poultices: It consists of moistened masses of vegetable materials or clay that are sometimes heated before application.

Penetration enhancers: e.g. Sulphoxides, amides, surfactants, pyrrolidones, calcium thioglycolate, propylene glycol.

19. Tablets: Solid unit dosage intended to be administered into the oral cavity. They are prepared either by molding or by compression methods. Tablets are swallowed whole and some after being chewed, some are dissolved or dispersed in water before administration and some are retained in the mouth where the active ingredients are liberated.

Fig. Tablets

20. Capsules: Capsules are solid dosage forms usually containing one dose of drug enclosed within a small water-soluble shell of a suitable form of gelatin. They are of two types hard gelatin and soft gelatin capsules. Hard gelatin capsules are generally used for filling solid medicaments although liquid can also be filled by incorporating suitable excipients in the formulation. They contain a body and a cap made up of gelatin, water plasticizer, and preservatives.

Soft gelatin capsules are used for filling solids, liquids as well as semisolids. The shell of soft gelatin capsules is formed, filled, and sealed. They contain a large number of plasticizers as compared to hard gelatin capsules which provide flexibility to the shell.

Fig. Capsules

21. Pastilles: Pastilles are solid medicated preparations intended to dissolve slowly in the mouth similar to troches and lozenges. The main difference being that pastilles are comparatively softer. These generally consist of glycerol and gelatin containing the medicament in solution or suspension. Acacia and sugar are sometimes used when hard pastilles are desired. e.g. Squill pastilles, Menthol and Eucalyptus pastilles.

22. Pessaries: Pessaries are solid dosage forms meant for introduction into the vagina where they melt or dissolve and exert a local action. Pessaries are prepared either by molding or by compression. Molded pessaries are usually cone-shaped and prepared like suppositories and hence are also known as vaginal suppositories. Compressed suppositories prepared by compression are available in a variety of shapes and sizes and are also known as vaginal tablets. e.g. Pessaries of Clotrimazole, Nystatin, Ichthammol.

23. Pills: Pills are small, round solid dosage forms containing one or more active ingredients meant for oral administration. Pills are formerly the most extensively used oral dosage form but they have been largely replaced by compressed tablets and capsules.

e.g. Phenolphthalein pills, hexylresorcinol pills.

24. Paints: Paints are solutions or dispersions of one or more active ingredients intended for application to the skin or mucosa of the mouth and throat usually with the help of a soft brush or a cotton swab. Skin paints often have a volatile solvent such as alcohol that evaporates quickly to leave a dry or resinous film of medicament. Throat paints are generally more viscous due to a high content of glycerine which being sticky, adheres to the affected area, and prolongs the contact time and hence action of the medicament. For example, compound paint of iodine also known as Mandl’s paint, crystal violet paint, etc.

25. Linctuses: They are viscous, sweet, liquid oral preparations that are usually prescribed for the relief of cold. They consist of simple solutions or admixture containing a high amount of syrup and sometimes, glycerine which in addition to giving sweet taste to the preparation have a demulcent action on the mucous membranes of the throat. For best results, linctuses should be used without dilution and sipped and swallowed slowly to ensure prolonged contact with the mucous membrane of the throat. E.g. Codeine linctus, tolu linctus.

26. Liniments: They are liquid or semi-liquid preparations meant for application to unbroken skin by friction or applied on lint or other suitable material and placed on the affected part. They may be alcoholic or oily or soapy solutions or emulsions. Alcoholic liniments are used generally for their rubefacient, counterirritant, mildly astringent, and penetrating effects. The oily or soapy liniments are milder in their action but are more useful when massage is required. Liniments should never be applied to the skin areas that are broken or bruised. E.g. camphor liniment, turpentine liniment.

27. Lotions: Lotions are liquid or semi-liquid preparations meant for application to unbroken skin without friction. They are either dabbed on the skin or applied on a suitable dressing and covered with waterproof material to reduce evaporation. An evaporating vehicle like alcohol may be used when a cooling effect is desired on application to the skin. Lotions generally contain antiseptic, astringent, anesthetics, germicides, protectives, or screening agents for the prevention or treatment of various skin diseases. e.g. calamine lotion, hydrocortisone lotion.

28. Lozenges: Lozenges are solid dosage forms containing medicaments in a sweetened and flavored base intended to dissolve slowly in the mouth. The base may be a hard sugar candy, glycerinated gelatin, or a combination of sugar with sufficient gum to give it form. Lozenges do not disintegrate in the mouth but dissolve slowly liberating the active ingredients which may be an antiseptic, local anesthetic, antibiotic, antihistaminic, antitussive, analgesic, or a decongestant. They are also known as Troches.

Fig. Lozenges

29. Mouthwashes: Mouthwashes are aqueous solutions containing one or more active ingredients for use in contact with the mucous membrane of the oral cavity usually after dilution with warm water. They contain additives such as alcohol, glycerine, synthetic sweeteners, surfactants, flavoring, and coloring agents. They are used for cleansing, refreshing, deodorizing, and antiseptic action. They may be either acidic or basic in their reaction and some instances are fairly effective in reducing bacterial concentration and odors in the mouth for short periods.

Fig. Mouthwashes

30. Nasal drops: They are solutions, suspensions, or emulsions containing active ingredients intended for installation into the nostrils usually with the help of a dropper. Nasal drops are mostly based on aqueous vehicles although oily drops are not common. Oily vehicles are usually not preferred since the oil may retard the ciliary action of the mucosa and may even cause lipoid pneumonia if drops of the oil enter the lungs.

31. Nasal sprays: They are suspensions or solutions of drugs intended for spraying into the nostrils. The chief uses of nasal sprays are to relieve nasal congestion and inflammation and to treat infections. They are intended to be retained in the nasal tract, they are usually vicious and coarse since fine droplets tend to penetrate further into the respiratory tract. These preparations are usually supplied in pressurized containers or plastic squeeze bottles.

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