II. Reading. ADMINISTRATION OF DRUDS

ADMINISTRATION OF DRUDS

The route of administration of a drug (how it is introduced into the body) is very important in determining the rate and completeness of its absorption into the bloodstream and speed and duration of the drug's action in the body.

The different methods used by physicians and allied health person­nel to administer drugs are listed below, with a brief discussion of each method:

Oral administration. The route of administration is by mouth. Drugs given orally must pass into the stomach and be absorbed into the blood­stream through the intestinal wall. Although this method is probably most acceptable to patients from the standpoint of convenience, it may have several disadvantages. If the drug is destroyed in the digestive tract by digestive juices or if the drug cannot pass through the intestinal mu­cosa, it will be ineffective. Also, oral administration is slower than other methods and disadvantageous if time is a factor in therapy.

Sublingual administration. In this route of administration, drugs are not swallowed but are placed under the tongue and allowed to dissolve in the saliva. Absorption may be rapid for some agents. Nitroglycerin tablets are taken this way to treat attacks of chest pain (angina pectoris). The nitroglycerin is rapidly absorbed into the bloodstream and opens the coronary arteries to increase blood flow to the heart muscle.

Rectal administration. Suppositories (cone-shaped objects contain­ing drugs) and water solutions are inserted into the rectum. At times, drugs are given by rectum when oral administration presents difficul­ties, such as when the patient is nauseated and vomiting.

Parenteral administration. This type of administration is accom­plished by injection through a syringe under the skin, into a muscle, into a vein, or into a body cavity. There are several types of paren­teral injections:

Subcutaneous injection. This injection is sometimes called a hypo­dermic injection, and is given just under the several layers of the skin. The outer surface of the arm and the anterior surface of the skin are usual locations for subcutaneous injections.

Intradermal injection. This shallow injection is made into the up­per layers of the skin. It is used chiefly in skin testing for allergic reac­tions. Short needles are used, and an elevation appears on the skin when an intradermal injection is given properly.

Intramuscular injection (I.M.). This injection is given into the muscle, usually into the buttocks. When drugs are irritating the skin or when a large volume of a long-acting drug is to be given, I.M. injec­tions are advisable.

Intravenous injection (I.V.). This injection is given directly into the veins. It is given when an immediate effect from the drug is desired or when the drug cannot be given into other tissues. Good technical skill is needed in administering this injection, since leakage of drugs into surrounding tissues may result in damage to the tissues.

Intrathecal injection. This injection is made into the sheath of membranes (meninges) which surround the spinal cord and brain. The effects of the drug administered so are usually limited to the central nervous system, and intrathecal injections are often used to produce anesthesia.

Intracavitary injection. This injection is made into a body cavity, as, for example, into the peritoneal or pleural cavity.

Inhalation. In this method of administration, vapors, or gases, are taken into the nose or mouth and are absorbed into the bloodstream through the thin walls of the air sacs in the lungs. Aerosols (particles of the drug suspended in air) are administered by inhalation.

Topical application. This is the local external application of drugs on skin or mucous membranes of the mouth or other surface. It is commonly used to accelerate the healing of abrasions, for antiseptic treatment of a wound, and as an antipruritic (against itching). Topical application may also include administration of drugs into the eyes, ears, nose, and vagina. Lotions are used most often when the skin is moist, or "weeping," and ointments and creams are used when the lesions are dry.

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