Dosage form

A dosage form is a pharmaceutical product prepared in a specific physical configuration for administration. It combines active drug ingredients with inactive substances called excipients, and the mixture is divided into individual doses. For instance, two amoxicillin products might both contain the same drug, but one could be a 500 mg capsule while the other is a 250 mg chewable tablet. The term "unit dose" can also describe single-use packaging, where each product is individually wrapped; however, the FDA distinguishes this as unit-dose "packaging" or "dispensing." Depending on context, "multiple unit dose" may refer either to several distinct drug products packaged together or to a single product that contains multiple drugs or doses.

The phrase "dosage form" sometimes refers only to the pharmaceutical formulation of a drug's ingredients, without considering the final consumable shape (like a capsule or patch). Because these terms overlap and can be ambiguous in the pharmaceutical industry, it is wise to be cautious when discussing them with others who might interpret the terminology differently.

Dosage forms vary by route of administration and include many liquid, solid, and semisolid types. Common examples are tablets, capsules, drinks, solutions, suspensions, and syrups. A combination drug, or fixed-dose combination (FDC), contains more than one active ingredient in a single product—such as a tablet, capsule, or syrup with multiple drugs. In naturopathy, dosages may also appear as decoctions and herbal teas, alongside conventional forms.

The route of administration (ROA) for a drug depends on its dosage form. Different forms may be available for the same drug, especially if certain conditions limit the ROA. For example, an unconscious patient or one with persistent nausea and vomiting cannot take oral medication, so alternatives like inhalational, buccal, sublingual, nasal, suppository, or parenteral routes are used. A specific dosage form may also be required due to chemical stability or pharmacokinetic issues. Insulin cannot be given orally because it is extensively metabolized in the gastrointestinal tract before reaching the bloodstream, so it never reaches its targets. Similarly, oral and intravenous doses of a drug like paracetamol differ for the same reason.

Oral dosage forms include pills (tablets or capsules), liquids such as syrups, solutions, elixirs, emulsions, and tinctures, as well as decoctions and herbal teas. Also included are orally disintegrating tablets, lozenges or candy (electuaries), thin films (like Listerine Pocketpaks or nitroglycerin) placed on or under the tongue or against the cheek, powders or effervescent powders/tablets often mixed into food, plants or seeds prepared as cannabis edibles, pastes such as high-fluoride toothpaste, and gases like oxygen (which can also be delivered through the nose).

Ophthalmic dosage forms include eye drops, lotions, ointments, and emulsions. Inhalation forms include aerosolized medication, dry-powder inhalers or metered dose inhalers, nebulizer-administered medication, smoking, and vaporizer-administered medication.

Talc is an excipient commonly used in pharmaceutical tablets. These tablets may be crushed into powder against medical advice or for recreational use. Illicit drugs that appear as white powder are often cut with cheap talc. Natural talc is inexpensive but contains asbestos, while asbestos-free talc costs more. Inhaled talc containing asbestos is generally accepted as able to cause lung cancer. The evidence about asbestos-free talc is less clear, according to the American Cancer Society.

Injection (parenteral) dosage forms include intradermal (ID), subcutaneous (SC), intramuscular (IM), intraosseous (IO), intraperitoneal (IP), intravenous (IV), and intracavernous (ICI) administration. These are usually solutions and suspensions.

Regarding unintended ingredients in injection: safe examples include eye drops (normal saline in disposable packages) distributed to syringe users by needle exchange programs. Unsafe examples include the injection of talc from crushed pills, which has been associated with pulmonary talcosis in intravenous drug users.

Topical dosage forms include creams, liniments, balms (such as lip balm or antiperspirants and deodorants), lotions, ointments, gels and hydrogels, ear drops, transdermal and dermal patches applied to the skin, and powders. It is not safe to calculate divided doses by cutting and weighing medical skin patches, because the substance may not be evenly distributed on the patch surface. For instance, fentanyl transdermal patches are designed to release the drug slowly over three days, and cut patches consumed orally have caused overdoses and deaths. Single blotting papers for illicit drugs, when injected from solvents in syringes, may also cause uneven distribution across the surface.

Other dosage forms include intravaginal administration (vaginal rings, capsules, tablets, suppositories), rectal administration (suppositories, suspensions and solutions as enemas, gels), urethral administration, and nasal sprays.