Different types of dosage forms:

Dosage forms can be classified into two major categories: 'Route of administration' & ‘Physical form’.
Route of administration: A path through which a drug is taken into the body is known as the Route of Administration. It is determined by the property of drug, therapeutic objective, and biopharmaceutical factors.

Types of dosage as per Route of Administration:

1. Oral dosage form: When the drug is administered through the mouth and it reaches the stomach and then gets absorbed, metabolized, and distributed to the tissue before it exerts its therapeutic effect. Examples: tablets, capsules, lozenges, pastilles, dental cones, granules, oral powder, and liquid preparations.
2. Topical dosage form: The application of drug directly to the surface of the skin, mainly used for the therapeutic effects is known as the Topical dosage form. Examples: ointments, creams, gels, poultice, pastes, dusting powder, transdermal patch, plasters, liniments, lotions, collodion, and aerosol sprays.
3. Rectal dosage forms: Rectal administration involves the use of the rectum as a route of administration for medicine and other fluids, which are absorbed via the rectum's blood vessels and flow into the body's circulatory system, which distributes the drug to the organs and biological systems. Examples: suppository and enema.
4. Parental dosage forms: When a drug is injected via a hollow needle into the body at various sites and to multiple depths is known as the Parental dosage form. Examples: Injections
5. Respiratory or Inhaled dosage form: When the medication particles are inhaled that is breathed in through the nose or mouth is called Respiratory or Inhaled dosage form. It includes inhaling gases, vapors, aerosols, powders, sprays, solutions, and suspensions. Examples:
6. Viginal dosage forms: The insertion of drugs into the vaginal canal to generate local or, less commonly, systemic pharmacological effects is referred to as vaginal dosage forms. Examples: pessary, viginal ring, douche, and intrauterine device.
7. Ophthalmic dosage forms: Specialized dosage forms designed to be instilled onto the external surface of the eye or administered inside the eye are known as Ophthalmic dosage forms. Examples: eye drops, ophthalmic ointment, and gels, ocular inserts, intravitreal injections, and implants.
8. Nasal dosage forms: Nasal dosage form refers to the route of administration in which medications are insufflated through the nose. It can be either topical or systemic administration because the medications delivered locally might have either solely local or systemic effects. Examples: nasal spray, nose drops, aerosol spray, metered-dose nebulizer, and saturated cotton pledget.
9. Otic Dosage forms: When substances are intended for administration either on the outer ear or into the auditory canal is known as Otic dosage forms. This is commonly used to treat or prevent ear infections, especially infections of the outer side of the ear canal. Examples: ear drops.

Types of dosage forms as per Physical form:

1. Solid dosage form: In the pharmaceutical industry, solid dosage formulations are essential dosage forms. Tablets, capsules, granules, sachets, powders, dry powder inhalers, and chewables are some examples. A unit dose of one or more medications is included in a solid dosage form. Examples: Tablets, capsules, granules, sachets, and powders
2. Semi-solid dosage form: Ointments, creams, and gels are Semi-solid dosage forms intended for topical application. They may be applied to the skin, placed onto the surface of the eye, or used nasally, vaginally, or rectally. The majority of these preparations are used for the effects of the therapeutic agents they contain. Those which are non-medicated are used for their physical effects as protectants or lubricants. Topical preparations are used for the localized effects produced at the site of their application, although some unintended systemic drug absorption may occur, it is usually in sub-therapeutic quantities. Examples: Ointments, creams, pastes, gels, and suppositories.
3. Liquid dosage forms: Liquid dosage forms are made by dissolving active ingredients in an aqueous or non-aqueous solvent, such as solutions, suspensions, and emulsions. Substances used in liquid dosage forms include vehicle, stabilizers and viscosity builders, preservatives, sweeteners, color, and taste. Furthermore, solubilizers are necessary for clear liquids, suspending agents for suspensions, and emulsifying agents for emulsions. Examples: Collodions, nasal and eye drops, Elixirs, suspensions, and gargles.
4. Gaseous dosage forms: Gaseous dosage forms are packed in a container which gets released upon applying pressure. The gas inside contains therapeutically active medicinal elements. The containers have valve systems with continuous or limited delivery. They are used for topical application on skin and as a local application into the nose and mouth. Examples: sprays, inhalers, aerosols, vaporizers and nebulizers, or atomizers.