Solid dosage form: An introduction with its principle.

What is solid dosage form?

Solid dosage form

Solid dosage forms are the substance having a definite shape and volume, which manufactured for the administration of active ingredients that acts at the site of action with its composition. These solid dosage forms are mostly available in the unit dose form, which includes tablets, capsules, powder, granules, and other suppositories.

When a drug is administered orally in dry state tablets and capsules, it is more convenient in form. It is effective and patients have no problem in their handling, Identification, and administration.

The bulk forms mean for the internal use that is supplied either as granules or in fine powder form. The bulk powder means for the external use that is dusting powders, insufflations, snuffs, and tooth powders.

Introduction of solid dosage form-

Generally, the drug substances are most frequently administered as solid dosage formulations, that are mainly administered through the oral route. Solid dosage forms are the most frequently used in the form of tablets and capsules as unit dosage forms. These are comprising a mixture of ingredients which is presented in a single rigid entity. The different types of solid dosage forms are including in lozenges, powder, granules, pills, and chewing gum, etc.

-These are prepared in various forms for administration through the oral route.

-This is the most common type of preparation.

-These are the convenience of administration, accuracy, and reproducibility of dosing, increased drug stability, and ease of mass production.

You may read- Drug dosage form.

Principle of solid dosage form-

Solid dosage forms are consisting of the two key trails in solubility and stability. The composition of insoluble and unstable drug form slows down the action of drugs. Generally, solid dosage forms are active at the site of administration within the required time with its action.

The solid dosage forms are approved from the process of screening for the selection of manufacturing. For the better composition of a solid dosage form are depends on the following factors are-

-Particle size and morphology

-Mixing and blending

-Flow and compaction

-Hygroscopicity and dissolution rates


-Release mechanisms

Excipients Added in Solid Oral Dosage Form-

-Excipients that Form Inclusion Complexes with Drug Molecules


-pH Adjusting Excipients

-Amorphous Solid Dispersions


-Self-Emulsifying Drug Delivery Systems (SEDDS)


-Soluble and Insoluble Filler Material

Classification of solid dosage form-



Tablets are the solid dosage forms containing one or more medicament with or without added pharmaceutical ingredients, or agents which used are diluents, colorants, disintegrates, solubilizers, binders and coatings, etc. Tablets are administered through the oral route.


These may be coated for appearance, for stability, to mask the bitter taste of the medication, or to provide controlled drug release.

Most of the tablets are manufactured by compression in the industrial scale, using highly sophisticated machinery. Various shapes and sizes of punches and dies enable the preparation of a wide variety of tablets of distinctive shapes, sizes, and surface markings.

Most tablets are intended to be swallowed whole. As per the requirement, a tablet may also be broken in half because many tablets are scored or grooved for this purpose, or more than a single tablet may be taken as a prescribed dose.

Specific Types of Tablets-

Chewable Tablets- These are the solid dosage form which containing medicinal substances with or without suitable diluents. These are small or flat which are placed between the tongue (sublingual) or the cheek (buccal) that is intended to be chewed. These are producing a pleasant tasting residue in the oral cavity that is easily swallowed and does not leave a bitter or unpleasant after-taste.

These are generally preferred for pediatric and geriatric patients who have difficulty in swallowing the whole tablets. Antacids are typically formulated as in the form of chewable tablets.

Delayed-release Tablet– These are the solid dosage form that releases a drug at a time other than promptly after administration.

Extended-release Tablet- These are the solid dosage form which containing a drug that allows at least a reduction in dosing frequency as compared to that drug presented in the conventional dosage form.

Coated Tablet– These are the solid dosage form that contains medicinal substances with or without suitable diluents that covered with a designated coating. These are covered with resins, gums, insoluble and inactive fillers, sugars, plasticizers, polyhydric alcohols, and waxes, etc.

These may contain flavoring agents. These are having a smooth, usually polished, and often colored.

Enteric-coated Tablets– These are the solid dosage form which has a special outer covering designed to dissolve in the small intestine. Once these are dissolved, the tablet disintegrates and the active ingredient can be absorbed by the patient.

These are used when the active ingredient is destroyed by substances in the stomach. In addition, these are indicated when the stomach is irritated by the drug in form of the tablet.

Film-coated Tablet- These are the solid dosage form that contains medicinal substances with or without suitable diluents. These are coated with a thin layer of a water-insoluble or water-soluble polymer.

 Sugar-coated Tablet- These are the solid dosage form that contains medicinal substances with or without suitable diluents that are coated with a colored or an uncolored water-soluble sugar.

Effervescent tablets-These are uncoated solid dosage forms which are generally contains acidic substances like-citric, tartaric acid, carbonates, and bicarbonates which are react rapidly in the presence of water by releasing carbon dioxide.

These are easily placed in the solution for a patient to drink. The patient easily absorbs the drug more rapidly because the active ingredient is in solution. These are intended to be dissolved or dispersed in water before use providing when-

-very rapid tablet dispersion and dissolution.

-pleasant-tasting carbonated drink.

Multi-layered tablets- These are the multilayered solid dosage form that consists of several different granulations that compressed on top of each other to form a single tablet. These are used with incompatible drug substances.

The capsule is in the form of medication in a gelatin container. It helps to mask the unpleasant taste of its contents.


Lozenges are solid dosage forms which are containing one or more medicinal agents in a flavored, sweetened base that intended to dissolve or disintegrate slowly in the mouth, releasing medication generally for localized effects. Lozenges are prepared by molding or compression.


These compressed form without a disintegrate and must be allowed to dissolve in the mouth. They are used for local activity (throat lozenges) or for systemic effects (vitamins). They are usually intended for the treatment of local irritation or infections of the mouth or throat but may contain active ingredients intended for systemic absorption after swallowing.


Capsules are intended to contain a specific quantity of fill, with the capsule size selected to accommodate that quantity closely. In addition to their medication content, capsules usually contain inert pharmaceutical substances, such as fillers, disintegrants, solubilizers, etc. When capsules are swallowed, the gelatin shell is dissolved by the gastrointestinal fluids, and releasing the active ingredient at site of action.


Capsules containing only nontherapeutic materials are termed placebos and are used widely in controlled clinical studies to evaluate the activity of a drug compared to a nondrug in a group of human subjects.

Specific Types of Capsules-

Hard Gelatin Capsules- Hard gelatin capsules are solid dosage forms in which one or more medicinal and inert substances are enclosed within small shells of gelatin. Capsule shells are produced in varying size, shape, thickness, softness, and color.

These are consisting of two parts — the body and the cap, are commonly used in extemporaneous hand filling operations as well as in small and large-scale manufacture of commercial capsules.

They usually are filled with powder mixtures and granules. After filling, the two capsule parts are joined for tight closure. These may seal and bonded through a variety of special processes for added quality assurance and capsule integrity.

Soft Gelatin Capsules– Soft gelatin capsules are the solid dosage form in which the drug is enclosed within a soluble, gelatin shell. The gelatin shell is plasticized by the addition of a polyol, like sorbitol or glycerin, and therefore a certain thicker consistency is than that of a hard-shell capsule.  Generally, the active ingredients are dissolved or suspended in a liquid vehicle.

These are one bodied which are formed, filled, and sealed in the same process. These may be filled with powders, semisolids, or liquids. These are soft and flexible. These are primarily used for oils and for active ingredients that are dissolved or suspended in oil.


Powders are the solid dosage form of medicament, which are used for internal or external use. They are available in crystalline or amorphous form. Generally, the range of powder size in 0.1 to 10 microns. These are mixtures of dry, finely divided drugs or chemicals that are intended for oral administration, parenteral administration, or external use.

Powder in capsule

Powder formulation has a uniform particle size distribution. If the particle size distribution is not uniform, then powder may distinct according to the different particle sizes that may result in inaccurate dosing or incompatible performance.

-The simple and compound powders used for internal use.

-Powders are also in the form of compressed tablets and Tablet triturates.

-Powders enclosed in form of cachets and capsules.

Specific types of powders for Internal use-

Bulk Powders- Bulk powders are non-potent which can be dosed with acceptable accuracy and safety using measuring devices such as the teaspoon, cup, or insufflator. These are used for internal use in the form of fine powders or granules and for external use in snuffs, dusting powders, and tooth powders.

Divided Powders– Divided powders are single doses of powdered medicinal individually wrapped in cellophane, metallic foil, or paper.


Granules generally are made up of first blending the powders together and then moistening the mixture to form a pasty mass. That mass is passed through a sieve and then dried in air or in an oven. These are prepared as a convenience for packaging, as a more stable product due to less surface exposure in the dosage form.

Granules in capsule

In granulation the particle size enlargement of homogeneously mixed powder ingredients. These are consisting of solid, dry aggregates of powder particles often supplied in single-dose sachets.

Some granules formulations are placed on the tongue and swallowed with water and others are intended that are to be dissolved in water before taking. Effervescent granules evolve carbon dioxide when they are added to water.


Pills are small, rounded solid dosage forms which are containing medicament that intended to be administered orally. The medicament is mixed with excipients to form a firm plastic mass. The mass is rolled to a uniform pill pipe, which is cut into a number of pills.


These are rounded in uniform size and shape to form pills. These are spherical in shape and are produced by rolling them under a wooden pill rounder. These are sometimes coated with varnish, silver leaf, and gold leaf to improve the finishing, and mask the unpleasant tastes and increase stability.

In ancient days pills were preferred because they are in spherical shape which can be easily swallowed.

Advantage of solid dosage form-

-The physical, chemical, physiological stability are enhancing long shelf life.

-There is less risk of chemical interaction between different medicaments.

-These are used by a single person easily.

-These are in the unit dose system.

– These are tasteless and elegance.

-These are having greater stability.

-These are accurate in dosage.

-These are economically easy to use.

-Ease of Transportation

-Ease of production

The disadvantage of solid dosage form-

-These are difficult for children to swallow.

-The onset of action is slow and, it depends on disintegration and dissolution.

-These are not for an unconscious person.

The packaging process for solid dosage form-

The packaging is the process of enclosing, protecting a product, and providing information about the product for distribution, storage, sale, and use.

You may read-Nasal dosage form.

Role of packaging in solid dosage form-



-Information transmission



Packaging for tablets and capsules-
Blister packaging

Blister Packaging- These are commonly used for unit-dose packaging for tablets and capsules. The principal components of a blister pack comprise of-

Forming film (blister)- A pocket inside which the product fits and materials used for forming films are-

-Polyvinyl chloride/polyethylene combinations



-Polyvinyl chloride (mostly used)

For added protection from moisture, polyvinylidene chloride (Saran) or polychlorotri-fluoroethylene (Aclar) films are may be laminated to PVC.  The moisture barrier of aclar is superior to the of saran coated PVC especially under the prolonged and extremely humid storage.

Backing– It is the lidding foil stacked over the back of a blister. Materials used for backing are –


-Paper-aluminum combinations

-Aluminum foil


Strip Packaging- It is formed by feeding two webs of a heat sealable flexible film through a heated crimping roller. It is used for both capsules and tablets and materials used are-

-Foil laminations (for moisture-sensitive products)



-Cellophane (Transparent plastic film formed from processed cellulose)


Alu-Alu packaging- It means aluminum foil at both the upper and lower side of the pack. It is similar to the blister packing but the only difference is that the forming film is formed of aluminum foil instead of plastic material.


Bottle packaging- These are commonly used for liquid pharmaceuticals as well as for tablets and capsules. Materials used for bottles-


-Polypropylene screw cap


Bottle mouth seal:

-Aluminum foil

Packaging of powders-

Powders are solid dosage forms which comprising of a large number of finely divided solid particles of drugs or mixture of drug and excipients. Powder packaging can be of following types are-


Pouches– A flexible pouch is generally formed during the product filling operation by either vertical forming/filling/sealing (f/f/s) operation and horizontal forming/filling/sealing (f/f/s) operation.

Materials used for pouches-




Sealants used-


-Ethylene-vinyl acetate (EVA)


Bottles– These are commonly used for liquid pharmaceuticals as well as for tablets, capsules, and powders especially in dusting powders. Materials used for the bottle are-


-Polypropylene screw cap


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