Drugs that Affect the Blood

Antianemic drugs, such as certain vitamins or iron, enhance the formation of red blood cells. Anticoagulants like heparin reduce blood-clot formation and ensure free blood flow through major organs in the body. Thrombolytic drugs dissolve blood clots, which can block blood vessels and deprive the heart or brain of blood and oxygen, possibly leading to heart attack or stroke.

Cardiovascular Drugs

Cardiovascular drugs affect the heart and blood vessels and are divided into categories according to function. Antihypertensive drugs reduce blood pressure by dilating blood vessels and reducing the amount of blood pumped by the heart into the vascular system. Antiarrhythmic drugs normalize irregular heartbeats and prevent cardiac malfunction and arrest.

Anti-infective Drugs

Anti-infective drugs are classified as antibacterials, antivirals, or antifungals depending on the type of microorganism they combat. Anti-infective drugs interfere selectively with the functioning of a microorganism while leaving the human host unharmed.

Antibacterial drugs, or antibiotics—sulfa drugs, penicillins, cephalosporins, and many others—either kill bacteria directly or prevent them from multiplying so that the body’s immune system can destroy invading bacteria. Antibacterial drugs act by interfering with some specific characteristics of bacteria. For example, they may destroy bacterial cell walls or interfere with the synthesis of bacterial proteins or deoxyribonucleic acid (DNA)—the chemical that carries the genetic material of an organism. Antibiotics often cure an infection completely. However, bacteria can spontaneously mutate, producing strains that are resistant to existing antibiotics.

Antiviral drugs interfere with the life cycle of a virus by preventing its penetration into a host cell or by blocking the synthesis of new viruses. Antiviral drugs may cure, but often only suppress, viral infections; and flare-ups of an infection can occur after symptom-free periods. With some viruses, such as human immunodeficiency virus (HIV), which causes acquired immunodeficiency syndrome (AIDS), antiviral drugs can only prolong life, not cure the disease.

Vaccines are used as antiviral drugs against diseases such like mumps, measles, smallpox, poliomyelitis, and influenza. Vaccines are made from either live, weakened viruses or killed viruses, both of which are designed to stimulate the immune system to produce antibodies, proteins that attack foreign substances. These antibodies protect the body from future infections by viruses of the same type (see Immunization).

Antifungal drugs selectively destroy fungal cells by altering cell walls. The cells’ contents leak out and the cells die. Antifungal drugs can cure, or may only suppress, a fungal infection.

Endocrine Drugs

Endocrine drugs correct the overproduction or underproduction of the body’s natural hormones. For example, insulin is a hormone used to treat diabetes. The female sex hormones estrogen and progesterone are used in birth control pills. To relieve uncomfortable symptoms of menopause, including sweating, hot flashes, and mood swings, as well as to delay some long-term consequences of menopause, including osteoporosis and atherosclerosis, physicians often prescribe the synthetic hormones estrogen, progestin (a synthetic form of progesterone), and sometimes androgens. This therapeutic approach is called hormone replacement therapy (HRT). However, recent studies indicate that HRT may be associated with an increased risk of breast cancer, heart attacks, strokes, and blood clots, and it is unclear if the benefits of HRT outweigh these risks. Each woman and her health-care provider should assess her need for menopausal symptom control and her potential risks and benefits before starting HRT.

Drug

Drug, substance that affects the function of living cells, used in medicine to diagnose, cure, prevent the occurrence of diseases and disorders, and prolong the life of patients with incurable conditions.

CLASSIFICATION

Drugs can be classified in many ways: by the way they are dispensed——over the counter or by prescription; by the substance from which they are derived—plant, mineral, or animal; by the form they take—capsule, liquid, or gas; and by the way they are administered—by mouth, injection, inhalation, or direct application to the skin (absorption). Drugs are also classified by their names. All drugs have three names: a chemical name, which describes the exact structure of the drug; a generic or proprietary name, which is the official medical name assigned by the United States Adopted Name Council (a group composed of pharmacists and other scientists); and a brand or trade name given by the particular manufacturer that sells the drug. If a company holds the patent on a drug—that is, if the company has the exclusive right to make and sell a drug, then the drug is available under one brand name only. After the patent expires, typically after 17 years in the United States, other companies can also manufacture the drug and market it under the generic name, or give it a new brand name.

A. Endocrine Drugs
B. Anti-infective Drugs
C. Cardiovascular Drugs
D. Drugs that Affect the Blood
E. Central Nervous System Drugs
F. Anticancer Drugs
G. Other Drugs