The Need for Dosage Forms
Most drug substances are administered in milligram quantities, much too small to be weighed on anything but a sensitive prescription or electronic analytical balance. When the dose of the drug is minute solid dosage forms such as tablets and capsules must be prepared with fillers or diluents so that the dosage unit is large enough to pick up with the fingertips. Besides providing the mechanism for the safe and convenient delivery of accurate dosage, dosage forms are needed for additional reasons:
• To protect the drug substance from the destructive influences of atmospheric oxygen or humidity (coated tablets, sealed ampoules)
• To protect the drug substance from the destructive influence of gastric acid after oral administration (enteric-coated tablets)
• To conceal the bitter, salty, or offensive taste or odor of a drug substance (capsules, coated tablets, flavored syrups)
• To provide liquid preparations of substances that are either insoluble or unstable in the desired vehicle (suspensions)
• To provide clear liquid dosage forms of substances (syrups, solutions)
• To provide rate-controlled drug action (various controlled-release tablets, capsules, and suspensions)
• To provide optimal drug action from topical administration sites (ointments, creams, transdermal patches, and ophthalmic, ear, and nasal preparations)
• To provide for insertion of a drug into one of the body’s orifices (rectal or vaginal suppositories)
• To provide for placement of drugs directly in the bloodstream or body tissues (injections)
• To provide for optimal drug action through inhalation therapy (inhalants and inhalation aerosols)
Source: Ansel’s Pharmaceutical Dosage Forms and Drug Delivery Systems (Ninth Edition)
