DRUG DOSAGE FORMS & DELIVERY SYSTEMS


Overview

The term dosage form refers to the physical manifestation of a drug as a solid, liquid, or gas that can be used in a particular way. Examples of common dose forms include tablets, capsules, creams, ointments, solutions, injections, and aerosols. The term delivery system has several definitions in healthcare and may include any of the following:

  • Device used to deliver the drug (e.g., teaspoon, syringe, nebulizer, IV fluid, infusion pump)
  • Design feature of the dose form that affects the delivery of the drug, such as the coating on some capsules that resists breakdown by the gastric fluids in the stomach so that the capsule will release medication, instead, into the intestines
  • Means for transporting a drug to its site(s) of action within the body

Drug Delivery systems differ in their pharmacological properties; that is, their sites of action, rate of delivery, and quantities of active ingredient delivered differ. Consider, for example, the drug nitroglycerin, commonly used to treat angina pectoris (pain in the chest and left arm associated with a sudden decrease in blood supply to the heart). Nitroglycerin dilates blood vessels, thus increasing blood supply to the heart and decreasing blood pressure. Three common delivery systems for nitroglycerin are sublingual tablets, placed under the tongue; ointment measured and applied directly on the skin; and transdermal patches, worn on the skin. Sublingual nitroglycerin tablets are fast acting but deliver their active ingredient for only a short period of time, about 30 minutes. Transdermal patches, in contrast, act slowly, with a delivery onset of about 30 minutes, but they can deliver a steady amount of the drug for up to 24 hours. The ointment is much less costly than the patch; it has a similar onset but a shorter duration of effect (up to 12 hours). The choice of delivery system depends on many factors, including the following:

  • active ingredient to be delivered
  • amount of active ingredient to be delivered
  • means or route that ingredient is to be delivered
  • to what sites
  • at what rate
  • over what period of time
  • for what purpose