Three name classifications of drugs are the chemical-scientific name, the generic name, and the brand or trade name.
A. Chemical-Scientific Name. This name specifically identifies the compound and is useful to a few technically trained personnel.
B. Generic Name. The generic or official name of a drug is assigned by the producer of the drug in collaboration with the Food and Drug Administration and Council on Drugs of the American Medical Association. The generic name may be used by any interested party and is usually the name found in the USP and NF. A generic drug name is not capitalized; for example, aluminum hydroxide.
C. Brand or Trade Name. Trade names are copyrighted terms selected by a manufacturer to designate a particular product Copyright laws prevent any other person from using the name, and other laws prevent pharmacists from substituting chemically identical products for the trade name article. When there are no longer any legal restrictions on the use of a brand name, the most widely accepted and familiar mane may become the official or generic name. Aspirin is an example--in 1963, this drug, previously listed as acetylsalicylic acid, officially became aspirin, USP.Sources of Drug Preparations
There are five main sources from which drugs are obtained--
A. Mineral. Many mineral substances found in nature are used in drugs. Examples: iodine, zinc oxide, and magnesium sulfate (Epsom salt).
B. Plant. Certain drugs are derived from vegetables and plants. Examples: digitalis, morphine, and senna pod extract.
C. Animal. The organs, tissues, and body fluids of animals (including man) are the source of some drugs. Examples: hormones, antitoxic serums, and gamma globulin from human blood.Types of Drug Preparations
D. Synthesis. Synthesis is the artificial building up of a chemical compound by the union of its elements. Drugs such as epinephrine that were once available only from natural sources can now be artificially reproduced through synthesis. Other drugs such as the sulfonamides were originally created through synthesis.
E. Microorganisms. Chemical substances produced by microorganisms such as funfi and bacteria are also sources of drugs. Examples: penicillin, tetracycline, and vaccines.
Drugs are compounded into various types of preparations, depending upon each drug's physical characteristics, the purpose for which intended, and the method by which it is to be administered. Some drugs are prepared in more than one form so they may be administered several ways. To give them bulk or form, drugs may be mixed with other substances which have no action or medicinal value. These substances are called vehicles. For a drug in aqueous solution, water is the vehicle; for a drug in an ointment, fatty substances such as petrolatum or lanolin are used as the vehicle. Drugs or mixtures of drugs that are divided into definite doses are dosage forms. Examples of dosage forms are capsules, tablets, ampules, and cartridge units. Some dosage forms prepared for oral administration are enteric coated with a special coating that resists the action of the stomach juices but dissolves in the intestine. This helps prevent nausea, irritation of the stomach lining, or destruction of the drug. Scored tablets are marked with an indented line across the surface so that they can be broken in half, if half a tablet is the dose required. Drugs prepared with flavored coatings or in flavored vehicles are exceptionally hazardous to children if left where they have access to them.
A. Solid Preparations.
Classification by Therapeutic Action1. Capsule. A drug placed in a gelatin container.B. Fluid Preparations.
2. Tablet. A drug compressed or molded into a flat disk or other shape.
3. Pill. A powdered drug molded into a sphere. The word "pill" as a general term used for tablets is a misuse of the word.
4. Troche. A drug preparation in a flat disk which is to be held in the mouth until dissolved.
5. Suppository. A drug which is molded into shape for insertion into a body opening other than the mouth. Its vehicle, such as cocoa butter, melts at body temperature and the drug is released.
6. Ointment. A drug suspended in a semi-solid base such as petrolatum.
7. Powder. A drug which is ground up and used in powder form.1. Fluid extract. A concentrated fluid preparation. Fluid extracts are 100-percent strength (1 ml. of the preparation contains 1 Gm. of the crude drug).
2. Tincture. An alcoholic solution of a drug. Tinctures of potent vegetable drugs are 10 percent in strength; of less potent drugs, 20 percent in strength.
3. Elixir. A solution containing water, alcohol, sugar, and flavoring substances, in which one or more drugs may be dissolved.
4. Spirit. An alcoholic or hydroalcoholic solution of a volatile drug.
In this major classification, drugs are grouped according to the effect they produce on the body to bring about a desired therapeutic result (as in the case of vasoconstrictors and diuretics), or according to the effect they produce on the pathogenic organism or the signs and symptoms of the disease (as in the case of fungicides, analgesics, and antipyretics.
A. Analgesics. These drugs are used to relieve pain without loss of consciousness. Aspirin is a mild analgesic. For relief of severe pain, morphine, and opium derivative, is the most valuable analgesic.
B. Anesthetics. These drugs are used to produce either a general or a local loss of sensation. An example of a general anesthetic is ether, which on inhalation, produces a loss of consciousness. An example of a local anesthetic is procaine hydrochloride, which on injection by special technique, produces local analgesia.
C. Antacids. Antacids are given to neutralize excess acid in the stomach. An example of an antacid is aluminum hydroxide.
D. Anthelmintics. These are drugs used to rid the body of worms (helminths). An example is piperazine citrate syrup.
E. Antiemetics. These are drugs used to relieve nausea and vomiting. An example is promazine hydrochloride.
F. Antibiotics. Drugs which inhibit the growth of or destroy bacteria and other microorganisms. An example is penicillin.
G. Sulfonamides. Drugs which inhibit the growth of or destroy bacteria, particularly the coccus form. One example is sulfisoxazole.
H. Antimalarials (plasmodicides). Drugs which prevent or cure malaria; for example, chloriquine phosphate.
I. Anti-Inflammatories. These drugs suppress local inflammatory reactions. An example is hydrocortisone ointment, 1 percent, used for some eye inflammatory conditions (ophthalmia).
J. Antifungals. These are drugs which check the growth of fungi. An example for external use (local application) is fungicidal foot powder. A recently developed antibiotic drug for oral administration in systemic treatment of fungus diseases of the skin is griseofulvin.
K. Antihistamines. These are drugs which counteract the effects of histamine. The release of abnormal amounts of histamine into body tissues is associated with acute allergic and hypersensitivity reactions. An example of an antihistamine is diphenhydramine hydrochloride.
L. Antiparasitics. Antiparasitics are used to eliminate skin infestation with mites. Examples for external use are gamma benzene hydrochloride ointment or lotion.
M. Antipyretics. These are drugs used to reduce the temperature during a fever. (They do NOT affect normal body temperature). An example is aspirin.
N. Antiseptics and Germicides.1. Antiseptics are chemical agents that inhibit the growth and development of microorganisms. They may be applied to living tissue. An example is benzethonium chloride solution 1:1000.
2. Germicides are chemical agents which are capable of destroying organisms (not necessarily spores). They may be applied both to living tissue and to inanimate objects for purposes of disinfection. An example is detergent iodine solution (iodophors).
O. Astringents. These are drugs which produce shrinkage of the skin or mucous membrane and cause a decrease in secretions. Astringents help to protect tissue from irritating substances. An example is zinc oxide ointment.
P. Cathartics. Cathartics are drugs which quicken and increase evacuation of the bowels. A laxative is a mild cathartic; a purgative is a stronger or more drastic cathartic. Dosage is frequently the determining factor in whether a cathartic will have a laxative or a purgative action. An example of a laxative is senna pod extract tablets.
Q. Counterirritants. These are drugs which cause irritation of the skin, thus increasing circulation and relieving inflammation in the structures beneath the skin. Linaments are counterirritants. An example of a drug with counterirritant action is methyl salicylate (oil of wintergreen).
R. Diuretics. These drugs are used to increase the production of urine. An example is acetazolamide.
S. Emollients and Protectives. These are drug preparations used on the skin and mucous membrane for a soothing effect.
1. Emollients are fatty preparations that soften the skin. An example is cold cream.
2. Protectives are preparations that form a film on the skin. An example is compound tincture of benzoin.
T. Inhalants. These are drugs which are inhaled and absorbed through the lungs. An example is aromatic spirits of ammonia.
U. Sedatives, Tranquilizers, and Hypnotics.
1. Sedatives are drugs which have a calming, quieting effect and, in large doses, induce sleep. An example is phenobarbital.
2. Tranquilizers are drugs that have a sedative effect that is characterized by relief of neuromuscular tension and anxiety without producing sleep. An example is chlorpromazine hydrochloride.
3. Hypnotics are drugs that induce sleep. Many drugs that have a sedative effect in small doses have a hypnotic effect when given in larger doses; for example, phenobarbital.
V. Stimulants. Stimulants are drugs which cause an increase in the activity of an organ or a system. Caffeine, a central nervous system stimulant, decreases drowsiness and fatigue. Digitalis, a heart stimulant, strengthens heart muscle contraction.Classification by Systemic Action
W. Vasoconstrictors. These are drugs which constrict the walls of blood, particularly peripheral vessels. Epinephrine is an example of a powerful systemic vasoconstrictor.
This major classification groups drugs according to the body systems that they affect. They may be applied directly to the system they are to affect (as in the case of antacids that are administered directly into the gastrointestinal tract to relieve a condition in the digestive system), or they may be administered via one system and affect another (as in the case of a heart stimulant that is administered orally).
A. Skin and Mucous Membranes. The drugs, usually applied locally, that affect the skin or mucous membranes are antiseptics, local anesthetics, counterirritants, antifungals, antiparasitics, and lical vasoconstrictors.General
B. Gastrointestinal Tract. Antacids and cathartics are among the drugs used to exert their main action on the digestive system. Some drugs used for specific gastrointestinal disorders act through the autonomic nervous system and have a therapeutic effect by decreasing smooth muscle movement and gastric acid secretion.
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.
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.
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.Internal Administration
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 which melts at body temperature. The mixture is shaped into a cone or cylinder which 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 mucous membrane of the cavity. 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 which produces a systemic effect when administered as a rectal suppository is aspirin.
Drugs may be given internally by several methods. When they are so given, the effect may be upon the whole body, or 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 induced to vomit so as 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 absorption has taken place. The action of drugs given this way 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 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 injuried so that he cannot be given the medication by mouth.
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 subcutanous 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 joints (intrasynovial).