C. Respiratory tract : The drugs that affect respiration include inhalants, stimulants, expectorants and depressants. D. Heart and blood vessels : Heart stimulants, vasodilators and vasoconstrictors are among the drugs that affect this system.
E. Nervous system : Drugs classified as analgesics, anesthetics, narcotics, hypnotics, sedatives and tranquilizers act on the central nervous system.
GENERAL ADMINISTRATION
disadvantages of rectal administration are the uncertainty of absorption and the chance that the drug may be expelled. D. Inhalation : Medications are administered by inhaling them into the lungs. This may be done by inhalation of aqueous preparations such as medicated steam, sprays and aerosols. Drugs given by inhalation include various preparations for respiratory infections and diseases, medicinal gases such as oxygen, and certain general anesthetics. Oily preparations are not given by inhalation since the oil would damage lung tissue. E. Injection : Drugs given by injection are administered with a sterile needle and syringe; injection methods are also referred to as parenteral (beside the intestine). A sterile injection method is used when rapid action by the drug is desired, when the drug might be destroyed by digestive juices or vomited if given by mouth, or when the patient is unconscious or injured so that he cannot take the medication orally. 1. Subcutaneous (hypodermic) : The drug is injected by syringe and needle into the tissue just beneath the skin. A preparation for subcutaneous use must be a sterile liquid capable of complete absorption or it will irritate the tissues. Although the subcutaneous injection may be given in almost any area of the body, the usual sites are the lateral (outer) aspect of the upper arms and the anterior (front) of the thighs. 2. Intramuscular : The drug is injected into a muscle, usually in the buttocks, sometimes in the upper arm or the thigh. The needle is inserted, at right angle to the skin, through the skin and subcutaneous tissue into the underlying muscle. This method gives more rapid absorption of the drug than subcutaneous injection gives. 3. Intravenous : Drugs administered by vein act very rapidly, because the whole dose passes directly into the blood stream. A comparatively small amount of sterile solution is given by intravenous injection; large amounts, administered drop by drop, are given by intravenous infusion. The usual site of injection is into the median basilic or median cephalic vein at the bend of the elbow. Intravenous injection is used when the drug is too irritating to be injected into other tissues, when immediate action is necessary, or when circulation is so poor that absorption from other tissue would be retarded. The IV administration of drugs is the responsibility of a medical officer; it is not a routine procedure performed by nurses or nonprofessional nursing personnel. When so performed, it must be in accordance with local policy directives. 4. Intradermal : The drug is injected into the upper layers of skin, rather than under the skin as in a subcutaneous injection. Minute amounts (0.1 ml. and less) are given intradermally, usually to test for drug sensitivity before administering larger amounts by other methods. Absorption from intradermal injection is slow. The medial (inner) surface of the forearm is the site most frequently used. 5. Intraspinal (intrathecal) : Drugs injected into the spinal canal are usually injected into the subarachnoid space. Some anti-infective drugs as well as spinal anesthesia are administered in this manner. The technique is the same as that required for lumbar puncture. 6. Other : Drugs may also be injected into the peritoneum (intraperitoneal), into the heart muscle (intracardiac), into bone (intraosseous) and into joints (intrasynovial).
Administration of drugs and medicines deals with the various ways by which they are applied to the body for local effect, or introduced into the body for systemic or for general effect. Some drugs may be used either way. External administration Topical (external) application of a drug is usually made for the local effect it will have on the skin or mucous membrane of a circumscribed area. Sometimes such an application is made for its effect in underlying tissues. The preparations most commonly used are: A. Solutions : These are applied locally as antiseptics, cleaning agents, astringents, vasoconstrictors, counterirritants or emollients (soothing agents). Solutions are also used as wet dressings, mouthwashes, gargles, irrigations and soaks. Since solutions evaporate, the effect produced is often temporary. B. Ointments : These provide a means of applying drugs for a prolonged local effect. The drug is mixed in a fatty material such as lard, petrolatum or lanolin, which becomes soft or liquid when warm but does not evaporate. Thus, the drug is kept in contact with the body for a long period. Ointments are not used on discharging wounds because they prevent free drainage. C. Suppositories : These are used for insertion into a body cavity, for example, in the rectum, urethra or vagina. The drug is mixed with a solid inert base that melts at body temperature. The mixture is shaped into a cone or cylinder that can be easily inserted. An example of a suppository base is cocoa butter. After the base melts in the cavity, the active drug comes in contact with the cavity’s mucous membrane. If the nature of the drug is such that it is absorbed through the membrane, a systemic effect may be produced. An example of a drug that produces a systemic effect when administered as a rectal suppository is aspirin. Internal administration Drugs may be given internally by several methods. When administered internally, the effect may be upon the whole body, in one of the systems, or only at the site where the drug is administered. The common methods of internal administration are: A. Oral : The most common way to give a medicine is by mouth, either in solid or liquid form. Giving a drug by mouth is the simplest way; it requires no special apparatus, it is painless, and absorption takes place in a natural manner. Furthermore, if a patient is sensitive to the drug, the stomach can be washed out or the patient can induce vomiting to prevent further absorption. B. Sublingual : A limited number of drugs are administered by placing a tablet or drop under the tongue. The drug is held there until absorbed. It is not swallowed, and a drink must not be taken until it has been absorbed. The resulting action of drugs is rapid. (The drug most commonly used sublingually is nitroglycerine). C. Rectal : Medications are given by rectum for the purpose of evacuating the colon, for local treatment of a diseased rectum or colon, and for general absorption. To induce a bowel movement, drugs may be given by an enema. Irrigations may be used to medicate the mucous membrane of the rectum or colon. Rectal suppositories also are frequently used. Another method by which substances are administered through the rectum is proctoclysis. Fluid is allowed to run into the rectum slowly, drop by drop, so that it is absorbed and does not enlarge the rectum. The
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Book Code: MTX1324B
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