Chemical substances helping a human body or an animal either for treatment of disease or to reduce suffering from pain are called medicine or drugs. The treatment of disease by chemical compounds which destroy the microorganisms without attacking the tissue of the human body is known as chemotherapy and the compounds used are called chemotherapeutic agents.
Classification of Medicinal Compounds
Antiseptics: Which prevent or destroy the growth of the harmful microorganisms. Common antiseptics are Dettol, Savlon, Cetavelon, acriflavine, Iodine, Methylene blue, mercurochrome and KMnO4. Dettol is a mixture of chloroxylenol and terpineol. Its dilute solution is used to clean wounds. Bithional is added to soap to impart antiseptic properties.
Disinfectants: The chemical compounds capable of completely destroying the microorganisms are termed as disinfectants. These are toxic to living tissues. These are utilized for sterilization of floor, toilets instruments and clothes. Example, 1% solution of phenol is disinfectant while 0.2% solution of phenol is antiseptic.
Analgesics: The substance which is used to get relief from pain. These are of two types:
Narcotics: These are alkaloids and mostly opium products, which cause sleep and unconsciousness when taken in higher doses. Examples are Morphine, Codeine, Heroin, etc.
Non-narcotics: Analgesics belonging to this category are effective antipyretics also. Examples are Aspirin and novalgin, Ibuprofen, Naproxen, etc.
Antipyretics: Antipyretics is used to bring down the body temperature in a high fever. Example: Aspirin, Analgin, Paracetamol and Phenacetin.
Antimalarials: It is used to bring down the body temperature during malarial fever. Example: Quinine, Chloroquine, Paraquine and Primaquine, etc.
Tranquillizers: The chemical substance which acts on the central nervous system and has a calming effect. Since these are used for mental diseases so are known as Psychotherapeutic drugs. They are if two types:
Sedative or Hypnotics: Reduce nervous tension and promote relaxation. Example: Reserpine, Barbituric acid and its derivatives as luminal and seconal.
Mood Elevator or Antidepressants: A drug used for the treatment of highly depressed patients who have lost their confidence. Example: Benzedrine (amphetamine)
Anaesthetics: These are chemical substances that help produce general or local insensibility to pain and other sensations. These are of two types:
Example: Gaseous form- Nitrous oxide, ethylene, Cyclopropane, etc.
Liquid form- Chloroform, divinyl ether and sodium pentothal, etc.
Antibiotics: The chemical substance produced from some microorganisms like fungi bacteria or mold and are used to inhibit the growth of other microorganisms. They are effective in the treatment of infectious disease. An example is Penicillin. It is a highly effective drug for Pneumonia, Bronchitis, Abscesses, Sore throat, etc.
Sulpha Drugs: Having great antibacterial powers. These are groups of drugs which are derivatives of sulphanilamide. Some other sulpha drugs are sulphathiazole, sulphaguanidine, sulpha pyridine, etc.
Antacids: Overproduction of acid in the stomach causes irritation and pain. In severe cases, ulcers are developed in the stomach. The only treatment of acidity is the administration of antacids, such as sodium hydrogen carbonate or a mixture of aluminium and magnesium hydroxide.
Antihistamines: A chemical histamine stimulates the secretion of pepsin and hydrochloric acid in the stomach. The drug cimetidine was designed to prevent interaction of histidine with the receptor present in the stomach wall.
Artificial Sweetening Agent
Sucrose adds to calorie intake and thus many people prefer to use artificial sweeteners. Saccharin is the first artificial sweetening agent. It is about 550 times as sweet as cane sugar. It appears to be entirely inert and harmless as it is excreted from the body as urine unchanged.
Food preservatives prevent spoilage of food due to microbial growth. The most commonly used preservatives include table salt, sugar, vegetable oils and sodium benzoate. Sodium benzoate is used in limited quantities and is metabolised in the body. Salts of sorbic acid and propanoic acid are used as preservatives.
These are agents which improve the cleansing properties of water. They are mainly of two types: soap and synthetic detergents. They help in the removal of fats which binds other material to the fabric or skin.
Soap: Soaps are sodium and potassium salt of long fatty acids, for example, stearic acid, oleic acid, etc.
Synthetic Detergents: They have all properties soaps but they do not contain any soap. These can be used as both soft and hard water.
To provide sufficient push to the rocket satellites to enter into space, some chemical fuels are used which are termed as rocket propellants.
Double base propellants
Mono Liquid propellant
Bi liquid propellant
Hydride Propellant: These consist of solid fuel and liquid oxidiser.