Solid dosage forms are available mostly in unit dosage forms, ie dosage form which are taken by numbers such as tablets, capsules, pills etc.
Some solids are packed and supplied in bulk. The bulk forms meant for internal use are supplied either as granules or fine powders. The bulk powder meant for external use are dusting powders, tooth powders etc.

POWDERS:

Powders are the solid dosage form of medicament, which are meant for internal or external use. They are available in crystalline and amorphous form. In crystalline powders the constituent atoms and molecules are packed in a regularly ordered, repeating three-dimensional pattern. Amorphous powders are non-crystalline materials which possess no long-range order.
Any material ranging in particle size from 0.1 to 10000 µ may be described as powder. However powders used in pharmacy generally have a size between 0.1 to 10 µ.
The powders are generally used in the following forms:

Bulk powder for internal use, Eg: Fine powders or granules
Bulk powder for external use, Eg: snuffs, dusting powders and tooth powders.
Simple and compound powders for internal use.
Powders in the form of compressed tablets and tablet triturates.
Powders enclosed in cachets and capsules.
Insufflations: Micronized powders meant for being blown in the nasal tract, ears, tooth sokets, vagina etc.
Parenteral powders: Powders for dissolution into vehicles before injection.

DUSTING POWDER:

Dusting powders are meant for application to the intact or broken skin.

They are meant for external applications.

Desired Property:

Ease of flow
Spreadability

The powder should adhere to the skin and possess good covering.
The dusting powder should protect the skin from drying and irritation.
Dusting powder should not have any irritant effect.

Types:

Dusting powders are of two types

MEDICAL
SURGICAL

Medical dusting powders are used mainly for superficial skin conditions whereas surgical dusting powders are used in body cavities and also on major wounds as a result of burns.
Surgical dusting powders must be sterile (free from bacteria or other living microorganisms) before their use.

Formulation:

It is generally prepared by mixing two or more ingredients one of which must be either starch, kaolin or talc. Talc and kaolin are most commonly used because these are chemically inert.

Use:

Dusting powders are mainly used for antiseptic (preventing the growth of disease-causing microorganisms.), astringent (a mild protein precipitant suitable for topical application to shrink tissues), adsorbent (Substance that binds to the drug surface), antiperspirant (a substance that is applied to the skin, especially under the arms, to prevent or reduce perspiration.) and antipruritic (used to relieve itching.)Action.

INSUFFLATIONS:

Insufflations are meant for powders being blown in various body cavities, like nose, throat, ears etc.
They are generally applied with the help of insufflators. It sprays the powder into a stream of finely divided particles all over the site of application.

Desired Quality

It should be finely divided powder.
They should be absolutely free from irritation and sensitizing quality.

Disadvantages:

It is difficult to obtain a measured quantity of the drug as a uniform dose
Particles adhere to each other and to the wall of the insufflators due to the electrostatic force.

Use:

Used for local effects, as in the treatment of ear, nose and throat infections with antibiotics (a medicine such as penicillin or its derivatives that inhibits the growth of or destroys microorganisms.).

SNUFFS:

These are finely divided solid dosage forms of medicament which are inhaled into nostrils for its antiseptic, bronchodilator and decongestion action.

DENTIFRICES:

Dentifrices or tooth powders are hygienic products of everyday use. They may also be medicated in order to exercise some definite action on individual person.

These are applied with the help of tooth brush for cleaning the surface of the teeth.

Formulation:

They contain abrasive agents such as calcium sulphate, magnesium carbonate, sodium carbonate and sodium chloride. It may also contain some detergent and suitable flavor.

Detergent action is given by incorporating surfactants.

Flavour and taste qualities are very significant in the formulation of dentifrices.

GRANULES:

The primary powder particles are made to adhere to form larger, multiparticle entities called granules and the process is known as granulation. The bitter, nauseous and unpleasant powders cannot be given in tablet form or in a capsule because a large number of them are required to be taken as a single dose.
They also cannot be given as liquid form because of stability problem.
Such medicaments are given in the form of granules. The drug is mixed with sugar, flavouring agent and a granulating agent to prepare a coherent mass, which is passed through a sieve to convert it into granules and then dried.
These dried granules are supplied in single dose sachets which are dissolved in water before taking.

Eg: Granules of antibiotics, such as erythromycin, and penicillin salts.

EFFERVESCENT GRANULES:

The effervescent granules are the specially prepared solid dosage form of medicaments, meant for internal use.
They contain a medicament mixed with citric acid, tartaric acid and sodium bicarbonate.
Sometimes saccharin or sucrose may be added as a sweetening agent.
Before administration, the desired quantity is dissolved in water, the acid and bicarbonate reacts together and produce effervescence. The carbonated water produced from the release of carbondioxide serves to mask the bitter taste of drugs. Moreover carbon dioxide stimulates the flow of gastric juice and helps in the absorption of medicaments.

3NaHCO3 + C6H8O7.H2O = C6H5Na3O7 + 3CO2 + 3H2O

Sodium Bicarbonate + Citric Acid = Sodium Citrate

TABLETS:

Tablets are solid unit dosage form which are prepared by molding or by compression.
Compressed tablets offer a number of advantages to the patients as well as the physician and the pharmacists and that is why their popularity continues to increase.
For the patient a tablet or a capsule is the most convenient form to use, because it neither involves measurement of dose and easy to carry. Tablets are also easy to be administered and dispensed. It is also a stable dosage form and maintain accuracy of dosage.

CAPSULES:

Capsules are solid unit dosage from in which one or medicaments and inert substances are enclosed within a small shell, generally prepared from a suitable form of gelatin.
Depending on their formulation, the gelatin capsule shell may be hard or soft.

PILLS:

Pills are small rounded solid dosage forms containing medicament and are intended to be administered orally. Pills are spherical in shape and sometimes coated with varnish, silver leaf, and gold leaf to improve the finish, mask the unpleasant tastes and increase stability.
In olden days pills were preferred because of their spherical shape which can be easily swallowed. But now a days it is not used because of the following reasons: