PHARMACEUTICAL DOSAGE FORM

DRUG DOSAGE AND TERMINOLOGY

• For convenience of dosage administration, most products are formulated to contain a drug’s usual dose within a single unit (e.g., capsule) or within a specified volume (e.g., 5 mL or a teaspoonful) of a liquid dosage form.

• To serve varying dosage requirements, manufacturers often formulate a drug into more than one dosage form and in more than a single strength.

DOSE

• Therapeutic dose : The median effective dose of a drug is the amount that will produce the desired intensity of effect in 50% of the individuals tested.

• Toxic dose : The median toxic dose is the amount that will produce a defined toxic effect in 50% of the individuals tested.

• The relationship between the desired and undesired effects of a drug is commonly expressed as the therapeutic index and is defi ned as the ratio between a drug’s median toxic dose and its median effective dose, TD50/ED50.

THE NEED FOR DOSAGE FORMS

• Drug substances are seldom administered alone; rather they are given as part of a formulation in combination with one or more nonmedicinal agents that serve varied and specialized pharmaceutical functions.

• Selective use of these nonmedicinal agents, referred to as pharmaceutical ingredients or excipients, produces dosage forms of various types. The pharmaceutical ingredients solubilize, suspend, thicken, dilute, emulsify, stabilize, preserve, color, fl avor, and fashion medicinal agents into efficacious and appealing dosage forms.

• The general area of study concerned with the formulation, manufacture, stability, and effectiveness of pharmaceutical dosage forms is termed pharmaceutics.

• Most drug substances are administered in milligram quantities, much too small to be weighed on anything but a sensitive prescription or electronic analytical balance.

• To protect the drug substance from the destructive influences of atmospheric oxygen or humidity (coated tablets, sealed ampuls)

• To protect the drug substance from the destructive infl uence 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, fl avored syrups)

• To provide liquid preparations of substances that are either insoluble or unstable in the desired vehicle (suspensions)

• 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)

CAPSULES

TABLETS

SOLID ORAL MODIFIED RELEASE DRUGS

OINTMENTS, CREAMS, AND GEL

SUPOSITORIES AND INSERTS

SOLUTIONS

PARENTERAL