$Unique_ID{BRK02991} $Pretitle{} $Title{The New Prescription Drug Reference Guide - How Drugs Work, part II} $Subject{Types CARDIOVASCULAR Antianginals Antiarrhythmics Antihypertensives Diuretics Cardiac Glycosides Anticoagulants Antihyperlipidemics Vasodilators Beta Blockers Calcium Channel Blockers EARS EYES GASTROINTESTINAL Antinauseants Anticholinergics Antiulcer Antidiarrheals HORMONES Thyroid Antidiabetic Steroids Sex Hormones ANTI-INFECTIVES Antibiotics Antivirals Vaccines anthelmintics pediculicide scabicide ANTINEOPLASTICS TOPICAL CENTRAL NERVOUS SYSTEM Sedatives Tranquilizers Antidepressants Amphetamines Anticonvulsants Antiparkinsonism Agents Analgesics Anti-Respiratory Antitussives Expectorants Decongestants Bronchodilators Antihistamines VITAMINS MINERALS} $Volume{} $Log{} Copyright (C) 1993 Publications International, Ltd. How Drugs Work, part II ------------------------------------------------------------------------------ Sex Hormones Although the adrenal glands secrete small amounts of sex hormones, these hormones are produced mainly by the sex glands. Estrogens are the female hormones responsible for secondary sex characteristics such as development of the breasts and maintenance of the lining of the uterus. Testosterone (androgen) is the corresponding male hormone. It is responsible for secondary sex characteristics such as a beard, a deepened voice, and the maturation of external genitalia. Progesterone is also produced in females--it prepares the uterus for pregnancy. Testosterone reduces elimination of protein from the body, thereby producing an increase in muscle size. Athletes sometimes take drugs called anabolic steroids (chemicals similar to testosterone) for this effect, but such use of these drugs is dangerous. Anabolic steroids can adversely affect the heart, nervous system, and kidneys. Most oral contraceptives (birth control pills) combine estrogen and progesterone, but some contain only progesterone. The estrogen in birth control pills prevents egg production. Progesterone aids in preventing ovulation, alters the lining of the uterus, and thickens cervical mucus--processes that help to prevent conception and implantation. Oral contraceptives have many side effects, so their use should be discussed with a physician. Conjugated estrogens are used as replacement therapy to treat symptoms of menopause in women whose bodies are no longer producing sufficient amounts of estrogen. Medroxyprogesterone is used to treat uterine bleeding and menstrual problems. It prevents uterine bleeding by inducing and maintaining a lining in the uterus that resembles the lining produced during pregnancy. In addition, it suppresses the release of the pituitary gland hormone that initiates ovulation. ANTI-INFECTIVES Antibiotics Antibiotics are used to treat a wide variety of bacterial infections. They are usually derived from molds or are produced synthetically. Antibiotics inhibit the growth of bacteria by interfering with their production of certain biochemicals necessary to sustain life or by interfering with their ability to use nutrients. The body's defenses then have a much easier time eliminating the infection. When used properly, antibiotics are usually effective. To adequately treat an infection, antibiotics must be taken regularly for a specific period of time. If you do not take an antibiotic for the prescribed period, microorganisms resistant to the antibiotic are given the opportunity to continue growing, and your infection could recur. Aminoglycosides, cephalosporins, erythromycins, penicillins (including ampicillin and amoxicillin), and tetracyclines are some examples of antibiotics. Antibiotics do not counteract viruses, such as those causing the common cold, so their use in cold therapy is inappropriate. Antivirals Antiviral drugs are used to combat viral infections. An antiviral drug called acyclovir is being used in the management of herpes. Acyclovir reduces the reproduction of the herpes virus in initial outbreaks, lessens the number of recurring outbreaks, and speeds the healing of herpes blisters. However, this antiviral drug does not cure herpes. Vaccines Vaccines were used long before antibiotics became available. A vaccine contains weakened or dead disease-causing microorganisms or parts of such organisms, which activate the body's immune system to produce a natural defense against a particular disease (such as polio or measles). A vaccine may be used to alleviate or treat an infectious disease, but most commonly it is used to prevent a specific disease. Other Anti-infectives Drugs called anthelmintics are used to treat worm infestations. Fungal infections are treated with antifungals (such as nystatin)--drugs that destroy and prevent the growth of fungi. A pediculicide is a drug used to treat a person infested with lice, and a scabicide is a preparation used to treat a person with scabies. ANTINEOPLASTICS Antineoplastic drugs are used in the treatment of cancer. Most of the drugs in this category prevent the growth of rapidly dividing cells, such as cancer cells. Antineoplastics are, without exception, extremely toxic and can cause serious side effects. But for many cancer victims, the benefits derived from chemotherapy with antineoplastic drugs far outweigh the risks involved. TOPICAL DRUGS Drugs are often applied topically (locally to the skin) to treat skin disorders with minimal systemic (throughout the body) side effects. Antibiotic creams or ointments are used to treat skin infections, and adrenocorticosteroids are used to treat inflammatory skin conditions. Another common dermatologic (skin) problem is acne. Acne can be--and often is--treated with over-the-counter drugs, but it sometimes requires prescription medication. Antibiotics such as tetracycline, erythromycin, or clindamycin are used orally or applied topically to slow the growth of the bacteria that play a role in the formation of acne pustules. Keratolytics (agents that soften the skin and cause the outer cells to slough off) are also sometimes prescribed. Some drugs applied to the skin do have effects within the body. For example, nitroglycerin is absorbed into the bloodstream from ointment or patches placed on the skin. The absorbed nitroglycerin dilates blood vessels and prevents anginal pain. Clonidine, scopolamine, and estrogen are available as transdermal patches, also. CENTRAL NERVOUS SYSTEM DRUGS Sedatives Medications used in the treatment of anxiety or insomnia selectively reduce activity in the central nervous system (brain and spinal cord). Drugs that have a calming effect include barbiturates, chlordiazepoxide, clorazepate, diazepam, doxepin, hydroxyzine, meprobamate, and oxazepam. Drugs to induce sleep in insomniacs include butabarbital, flurazepam, temazepam, and triazolam. Tranquilizers Major tranquilizers or antipsychotic agents are usually prescribed for patients with psychoses (certain types of mental disorders). These drugs calm certain areas of the brain but permit the rest of the brain to function normally. They act as a screen that allows transmission of some nerve impulses but restricts others. The drugs most frequently used are phenothiazines, such as chlorpromazine and thioridazine. Haloperidol, a butyrophenone, has the same effect as chlorpromazine. Antidepressants Tricyclic antidepressants (such as amitriptyline), tetracyclic antidepressants (such as maprotiline), and monoamine oxidase (MAO) inhibitors (such as phenelzine) are used to combat depression. Antidepressants are also used in the preventive treatment of migraine headaches, although the manner in which they help these headaches is not clearly understood. Antidepressants may produce serious side effects, and they can interact with other drugs. MAO inhibitors can also interact with certain foods, resulting in dangerous increases in blood pressure. Therefore, they should be used very carefully. Amphetamines Amphetamines or adrenergic drugs are commonly used as anorectics (drugs used to reduce the appetite). These drugs temporarily quiet the part of the brain that causes hunger, but they also keep a person awake, speed up the heart, and raise blood pressure. After two to three weeks, these medications begin to lose their effectiveness as appetite suppressants. Amphetamines stimulate most people, but they have the opposite effect on hyperkinetic children. Hyperkinesis (the condition of being highly overactive) is difficult to diagnose or define and requires a specialist to treat. When hyperkinetic children take amphetamines or the adrenergic drug methylphenidate, their activity slows down. Most likely, amphetamines quiet these youngsters by selectively stimulating parts of the brain that ordinarily provide control of activity. Anticonvulsants Drugs such as phenytoin and phenobarbital are used to control seizures and other symptoms of epilepsy. They selectively reduce excessive stimulation in the brain. Antiparkinsonism Agents Parkinson's disease is a progressive disorder that is due to a chemical imbalance in the brain. Victims of Parkinson's disease have uncontrollable tremors, develop a characteristic stoop, and eventually become unable to walk. Drugs such as benztropine, trihexyphenidyl, levodopa, and bromocriptine are used to correct the chemical imbalance, thereby relieving the symptoms of the disease. Benztropine and trihexyphenidyl are also used to relieve tremors caused by other medications. Analgesics Pain is not a disease but a symptom. Drugs used to relieve pain are called analgesics. These drugs form a rather diverse group. We do not fully understand how most analgesics work. Whether they all act on the brain is not known. Analgesics fall into two categories; they may be either narcotic or nonnarcotic. Narcotics are derived from the opium poppy. They act on the brain to cause deep analgesia and often drowsiness. Some narcotics relieve coughing spasms and are used in many cough syrups. Narcotics relieve pain and give the patient a feeling of well-being. They are also addictive. Manufacturers have attempted to produce nonaddictive synthetic narcotic derivatives but have not yet been successful. Many nonnarcotic pain relievers are commonly used. Salicylates are the most commonly used pain relievers in the United States today. The most widely used salicylate is aspirin. While aspirin ordinarily does not require a prescription, many doctors may prescribe it to treat such diseases as arthritis. The aspirin substitute acetaminophen may be used in place of aspirin to relieve pain. It does not, however, reduce inflammation (such as that caused by arthritis). A number of analgesics contain codeine or other narcotics combined with nonnarcotic analgesics (such as aspirin or acetaminophen). These analgesics are not as potent as pure narcotics but are frequently as effective. Because these medications contain narcotics, they have potential for abuse and must be used with caution. Anti-inflammatory Drugs Inflammation is the body's response to injury. It causes swelling, pain, fever, redness, and itching. Aspirin is one of the most effective anti-inflammatory drugs. Other drugs, called nonsteroidal anti-inflammatory drugs (for example, fenoprofen, ibuprofen, indomethacin, naproxen, and tolmetin), relieve inflammation and may be more effective than aspirin in certain individuals. Steroids are also used to treat inflammatory diseases. When sore muscles tense, they cause pain, inflammation, and spasm. Skeletal muscle relaxants (for example, orphenadrine, aspirin, and caffeine combination; meprobamate and aspirin combination; and chlorzoxazone and acetaminophen combination) can relieve these symptoms. Skeletal muscle relaxants are often given in combination with an anti-inflammatory drug such as aspirin. Some doctors, however, believe that aspirin and rest are better for alleviating the pain and inflammation of muscle strain than are skeletal muscle relaxants. RESPIRATORY DRUGS Antitussives Antitussives control coughs. There are numerous over-the-counter (nonprescription) antitussives available--most of them contain dextromethorphan. Codeine is a narcotic antitussive that is an ingredient in many prescription cough medications. These cough syrups must be absorbed into the blood and must circulate and act on the brain before they relieve a cough. Expectorants Expectorants are used to change a nonproductive cough to a productive one (one that brings up phlegm). Expectorants are supposed to increase the amount of mucus produced. However, drinking water or using a vaporizer or humidifier is probably more effective in increasing mucus production. Popular expectorant ingredients include ammonium chloride, guaifenesin, potassium guaiacolsulfonate, and terpin hydrate. Decongestants Decongestants constrict blood vessels in the nose and sinuses to open up air passages. They are available as oral preparations, nose drops, and nose sprays. Oral decongestants are slow-acting but do not interfere with production of mucus or movement of the cilia (special hairlike structures) of the respiratory tract. They can, however, increase blood pressure, so they should be used cautiously by patients with high blood pressure. Topical decongestants (nose drops or spray) provide almost immediate relief. They do not increase blood pressure as much as oral decongestants, but they do slow the movement of the cilia. People who use these products may also develop a tolerance for them. Tolerance can be described as a need for ever-increasing dosages to achieve a beneficial effect. The additional disadvantage of developing tolerance is that the risk of side effects increases as the dosage increases. Topical decongestants should not be used for more than a few days at a time. Bronchodilators Bronchodilators (agents that open airways in the lungs) and agents that relax smooth-muscle tissue (such as that found in the lungs) are used to improve breathing. Theophylline and aminophylline are oral bronchodilators commonly used to relieve the symptoms of asthma and pulmonary emphysema. Albuterol and metaproterenol are inhalant bronchodilators, which act directly on the muscles of the bronchi (breathing tubes). Antihistamines Histamine is a body chemical that, when released in the body, typically causes swelling and itching. Antihistamines counteract these symptoms of allergy by blocking the effects of histamine. For mild respiratory allergies, such as hay fever, antihistamines can be used. Diphenhydramine and other antihistamines are relatively slow-acting. Severe allergic reactions sometimes require the use of epinephrine (which is not an antihistamine); in its injectable form, it is very fast-acting. Some types of antihistamines are also used to prevent or treat the symptoms of motion sickness. Diphenhydramine and meclizine are examples of drugs used specifically for this purpose. VITAMINS AND MINERALS Vitamins and minerals are chemical substances that are vital to the maintenance of normal body function. Most people obtain enough vitamins and minerals in their diet, but some people have vitamin deficiencies. Serious nutritional deficiencies lead to diseases such as pellagra and beriberi, which must be treated by a physician. People who have an inadequate or restricted diet, people who have certain disorders or debilitating illnesses, and women who are pregnant or breast-feeding are among those who may benefit from taking supplemental vitamins and minerals. However, even these people should consult a doctor to see if a true vitamin deficiency exists. ---------------- The material contained here is "FOR INFORMATION ONLY" and should not replace the counsel and advice of your personal physician. Promptly consulting your doctor is the best path to a quick and successful resolution of any medical problem.