Dosage Forms of Drugs

Study Notes

Dosage Forms of Drugs

Dosage forms are the ways drugs are given to a patient
Types of dosage forms include:
- Enteral
- Parenteral
- Inhalation
- Topical
- Buccal
- Rectal

Enteral Dosage Forms

Oral Dosage Forms:
- Solids:
  - Tablets: Solid dosage forms of varying weight, size, and shape made by compressing the drug with pharmacologically inert substances. Examples include simple tablets (e.g., aspirin), coated tablets (to mask bad taste), enteric-coated tablets (to dissolve in the intestine to avoid stomach irritation), chewable tablets, and effervescent tablets (e.g., vitamin C tablets).
  - Capsules: Gelatin shells containing individual drug doses, often used to mask bad taste. Types include hard gelatin capsules (for powders) and soft gelatin capsules (for liquids), and Spansule (sustained-release).
  - Powders: May be dispensed in packets or as effervescent granules. Effervescent powders are made by combining the drug with sodium bicarbonate and tartaric or citric acid. When added to water, carbon dioxide is released masking any unpleasant taste.
- Liquids:
  - Solutions (Aqueous and Non-aqueous): Liquid preparations containing one or more soluble substances dissolved in water (aqueous) or alternative solvents (non-aqueous). Examples include Aromatic Water (aqueous solution of peppermint oil), Syrup (highly concentrated aqueous sugar solution), Elixir (alcoholic solution), Spirit (volatile oil in alcohol), and Tincture (alcoholic preparation of vegetable drugs)
  - Suspension: A preparation where insoluble solid drugs are suspended in an aqueous vehicle. Must be shaken before use.
  - Emulsion: A mixture of two immiscible liquids (like oil and water) where one liquid is dispersed in the form of small droplets within the other. It is stabilized by an emulsifying agent.

Parenteral Dosage Forms

Liquid (Injection):
- Ampoules: Single dose of sterile solution or suspension.
- Vials: Rubber-capped glass, single or multi-dose preparations. Unstable drugs are often prepared as vials where the solvent is added later.
- Bottles : Used for large amounts of drugs like glucose or saline.
- Insulin pen injector: Contains a cartridge with insulin and replaceable needles for subcutaneous injections.
Solid (Implants):
- Pellets: Tiny solid dosage form used for implants.

Inhalation Dosage Forms

Gases: Oxygen and general anesthetics.
Vapors: Highly volatile liquids like halothane
Systemic Inhalation: Drugs vaporized by steaming.
Aerosols: Liquid or solid suspensions in a gas, administered via nebulizers or metered-dose inhalers (MDIs).
Powders: Administered through Spinhalers

Topical Dosage Forms

Local Effect on mucous membranes and skin:
- Ointments: Fatty bases (vaseline) immiscible with water.
- Creams: Prepared with bases miscible with water.
- Gels: Solids/semisolids that become liquid when warmed.
- Lotions: Aqueous preparations applied without rubbing (e.g., calamine lotion)
- Dusting powders: Applied to the skin for protection or therapeutic effect (e.g., talc, antifungal)
Systemic effect: Transdermal patches (e.g., nitroglycerin patch) for absorption directly into the bloodstream.

Buccal Dosage Forms

Sublingual tablets: Placed under the tongue for rapid disintegration (e.g., nitroglycerin for angina).
Lozenges: Flavored tablets that dissolve slowly in the mouth.
Mouth wash, gargle, paint, and gel

Rectal Dosage Forms

Liquid (Enema): Used to evacuate the lower GI tract or administer drugs (e.g., corticosteroids in ulcerative colitis).
Solid (Suppository): Examples include glycerin suppositories (to evacuate) or medicated suppositories (for drug delivery).