Chemtstry in Human Health Preparation and Properties
→ Chemistry influences almost every aspect of human life. The principles of chemistry have been used for the benefit of mankind. Of course, sickness and diseases remind us of medicines-again chemicals. Explosives, fuels, rocket propallents, building and electronic materials, etc., are all chemicals. Air pollution, hereditary disorders, accidents, bacterial infections etc. are reason for diseases in human beings. Various medicines are used for treatment of these diseases.
→ Medicines used in different fields of medical sciences like Ayurvedic, Unani, Allopathy etc.. are either naturally occurring or synthesised materials by che mists. Use of chemicals for therapeutic effect is called chemotherapy.
→ Drugs are chemicals of low molecular masses (∼100-500u). These interact with biomolecules like carbohydrates, proteins. lipids, nucleic acid etc. that take part in various biochemical reactions and produce a biological response. These are used in diagnosis, prevention and treatment of diseases.
→ When the biological response is therapeutic and useful, these chemicals are called medicines. A Doctor select suitable medicine according to the symptoms of the disease. Medicines can be classified on various basis like pharmacological effect, chemical structure, target molecules etc. If these are consumed in doses higher than the recommended ones, they may cause havoc. They may act as poisons and may even prove to be fatal.
→ A doctor prescribed medicine according to symptoms of diseases. Medicines are classified on the basis following:
- On the basis of pharmalogical effect.
- On the basis of function of medicines.
- On the basis of chemical structure.
- On the basis of t.raget molecules.
→ Now we will discuss functions, structure and medicinal effect of various drugs.
Analgesics of Chemtstry in Human Health
→ Medicines used to get relieve from pain are called analgesics. These reduce or abolish pain without causing impairment of consciousness, mental confusion, incoordination or paralysis or some other disturbances of nervous system. These are classified as follows:
→ Non-narcotic (Non-addictive) Analgesics These are non-habit forming chemicals which reduce mild to moderate pain such as headache, toothache, muscle and joint pain etc. These are also termed as non-addictive.
→ These drugs do not produce sleep, unconsciousness. Aspirin and paracetamol belong to the class of non-narcotic analgesics. Asprin is the most familiar example. These dris have many other effects such as reducing fever (antipyretic) and preventing platelet coagulation. Aspirin should not be taken empty stomach because on hydrolysis it forms salicylic acid which produces ulcers in walls of empty stomach.
→ Narcotic Drugs Drugs which produce sleep and unconsciousness are called narcotics. Morphine and many of its homologues, when administered in medicinal doses, relieve pain and produce sleep. These are habit forming drugs. For example, Morphine and Codeine. Morphine diacetate is commonly known as heroin.
Tranquilizers of Chemtstry in Human Health
→ Tranquilizers are a class of chemical compounds which influence the central nervous systeme and reduce anxiety and tension and thus are used to cure mental diseases. These are neurologically active drugs. These relieve anxiety, stress, irritability or excitement by inducing a sense of well-being. They form an essential component of sleeping pills. There are various types of tranquilizers.
→ They function by different mechanisms. They are the common constituents of sleeping pills. Iproniazid and pheneizine are two such drugs. Some tranquilizers namely, chiordiazepoxide and meprobamate, are relatively mild tranquilizers suitable for relieving tension. Equanil is used in controlling depression and hypertension.
→ Barbiturates Derivatives of barbituric acid viz., Veronal, Amytal, Nembutal, Luminal and Seconal constitute an important class of tranquilizers. These derivatives are called barbiturates. Barbiturates are hypnotic, i.e.. sleep producing agents. Some other substances used as tranquilizers are valium and serotonin.
Antimicrobials of Chemtstry in Human Health
→ An antimicrobial tends to kill or prevent development of microbes. It inhibits the pathogenic action of microbes such as bacteria, fungi and virus selectively. Diseases in human beings and animals may be caused by a variety of micro-organisms such as bacteria, virus, fungi and other pathogens.
→ An antimicrobial tends to destroy or prevent development or inhibit the pathogenic action of microbes such as bacteria (antibacterial drugs), fungi (antifungal agents), virus (antiviral agents), or other parasites (antiparasitic drugs) selectively. Antibiotics, antiseptics and disinfectants are antimicrobial drugs.
→ Micro organisms are very small in size. These can be observed under microscope only. Many substances are secreted in body which destroys these micro organisms but there is some problem in secration of these substances, then these micro organisms causes diseases by infecting tissues. The diseases caused by these micro organisms can be controlled by three methods:
→ Use of such medicines which destroys micro organisms in the body. These medicines are called bactericidal.
Use of such medicines which stops the growth of the micro organisms. These are known as bacteriostatic.
By increasing immunity in the body.
Antibiotics of Chemtstry in Human Health
→ Antibiotics are the drugs produced by micro organisms and are used to kill or prevent the growth of other micro organisms by intervening in their metabolic processes.
→ These are the substances (produced wholly or partially by chemical synthesis) which in low concentrations inhibit the growth of micro.organisms or destroy them by intervening in their metabolic processes. Antibiotics are very specific in their nature.
→ Paul Edrlich. a German Bacteriologist, investigated arsenic based structures in order to produce less toxic substances for the treatment of syphilis. He developed the medicine, Arsphenamine. known as Salvarsan.
→ Paul Edrlich got Nobel prize for Medicine in 1908 for this discovery. It was the first effective treatment discovered for syphilis. In 1932, he succeeded in preparing the first effective antibacterial agent. Prontosil, which resembles in structure to the compound, salvarsan. Soon it was discovered that in the body prontosil is converted to a compound called suiphanilamide, which is the real active compound thus the suipha drugs were discovered.
→ A large range of sulphonamide analogues was synthesised. One of the most effective is suiphapyridine.
→ Penicillin was the first antibiotic discovered by Alexander Fleming in 1929. It is a narrow-spectrum antibiotic. Alexander Fleming was given Nobel Prize for the discovery of penicillin in 1945.
Antibiotics are of two Types
→ Bactericidal Antibiotics : Bactericidal antibiotics have cidal (killing) effect on microbes. For example, Penicillin, Ofloxacin, Aminoglycosides, etc.
→ Bacteriostatic AntibiotIcs : Bacteriostatic antibiotics have a static (inhibitory) effect on microbes.
For example, Erythromycìn, Tetracycline, Chioramphenicol, etc.
→ Bacteria can be Gram positive or Gram negative. The range of bacteria or other micro-organisms that are affected by a certain antibiotic is expressed as its spectrum of action.
→ Broad Spectrum Antibiotics : Antibiotics which kill or inhibit a wide range of Gram-positive and Gram negative bacteria are said to be broad spectrum antibiotics.
→ Narrow Spectrum Antibiotics : Those effective mainly against Gram-positive or Gram-negative bacteria are called narrow spectrum antibiotics.
→ Limited Spectrum Antibiotics : If effective against a single organism or disease, they are referred to as limited spectrum antibiotics.
→ With the help of antibiotics, many infectious diseases can be cured. These are highly specific in nature. Their small amounts effective against micro organisms. Some of the important antiboitics are:
→ Penicillin : Total six naturally occurring penicillin are separated. Penicillin G has a narrow spectrum and is mostly used. Ampicillin and amoxycillin are synthetic modifications of penicillins. These have broad spectrum.
→ It is absolutely essential to test the patients for sensitivity (allergy) to penicillin before it is administered. In India, penicillin is manufactured at the Hindustan Antibiotics in Pimpri and in private sector industry.
→ Chloramphenicol : It is also known as chioromycetin. Chioramphenicol is used in treatment of acute fever, dysentery, typhoid, meningitis, pneumonia etc. Streptomycin is hacteriostatic in low concentration and bactericidal at high concentration. It is given for tuberculosis.
→ Streptomycin : ¡t is used in the treatment of tuberculosis. It is a broad spectrum antibiotic. It is also used in mental diseases and pneumonia.
→ Tetracycliries : The main antibiotics of this group is iromycine. teramycine. Iromycine is used in treatment of eye infection and tetramycine is used in treatment of typhoid.
→ Suipha Drugs : These are suiphonamides and their derivatives. These are used in treatment of diseases caused by cocci infection. Examples are : Sulfadiazine, Sulfaguanidine. Sulfapvridine. Sulfathizole etc.
Antiseptics of Chemtstry in Human Health
→ Drugs which are used either to kill or stop the growth of micro organisms are called antiseptics. Antiseptics are applied to the living tissues such as wounds, cuts, ulcers and skin diseases in the form of antiseptic creams like Furacin and Soframycin. Some important examples of antiseptics are dettol which is a mixture of chioroxylenol and terpineol. Bithional is added to soaps to impart antiseptic properties to reduce the odours produced by bacterial decay of organic matter on the skin.
→ Tincture of iodine is a 2-3% solution of iodine in alcohol, which is a powerful antiseptic for wounds. lodoforni (CHI3) is also used as an antiseptic for wounds.
→ Antihistomines or Antiallergic Drugs The chemicals which are used for treatment of allergy are known as antihistamines or anti-allergic drugs. The allergy is due to a chemical called histamine. The drugs which interfere with the natural action of histamine for binding sites of receptor where histamines exerts effects are called antihistamines.
→ Histamine is a potent vasodilator. ¡t has various functions. It contracts the smooth muscles in the bronchi and gut and relaxes other muscles, such as those in the walls of fine blood vessels.
→ Histamine is also responsible for the nasal congestion associated with common cold and allergic response to pollen. Histamine is produced by decarboxylation of alpha amino acid. histidine.
→ In case of allergies such as the common cold, the histamines bind to the receptors in the nasal cavity and cause blood vessels to swell and secrete excess fluid, causing sneezing and a running nose. Antihistamine drugs provide relief from the allergic effects of histamines by attaching themselves to the receptors and thus preventing histamines from binding to receptors. Some of the examples are given below:
→ There are some side effects of taking antihistamines like unconsciousness, sleep etc. Therefore, these drugs should be taken in adequate amount as prescribed by Doctor.
Anti Fertility Drugs of Chemtstry in Human Health
→ Chemical substances which are used to check pregnancy in women are called anti-fertility drugs. These control the female menstrual cycle and ovulation. All the drugs contain chemicals related to female sex hormones have a steroid ring structure.
→ The increased population has caused many social problems in terms of food resources, environmental issues, employment, etc. To control these problems, population is required to be controlled. This has lead to the concept of family planning.
→ Antifertility drugs are of use in this direction. Birth control pills essentially contain a mixture of synthetic estrogen and progesterone derivatives. Both of these compounds are hormones. It is known that progesterone suppresses ovulation.
→ Estrogen controls the menstrual cycle while progesterone suppresses ovulation. Some of the examples of antifertility drugs are Novestrol. Mifepristone etc.
→ Mifepristone is used as ‘morning after pill”. It works after a women is pregnant and fertiised egg has attached to the wall of the uterus. It causes the uterus to
→ expel the egg thereby terminating the pregnancy. Norethindrone is an example of synthetic progesterone derivative most widely used as antifertility drug. The estrogen derivative which is used in combination with progesterone derivative is ethynylestradiol (Novestrol).
→ Fluoro derivatives of aromatic hydrocarbons are used as antifertility drugs in laboratory. Antifertility chemicals are also found in Soybeans, Peas etc. For example, Metaxylohydroquinone is found in oil of peas.
Antacids of Chemtstry in Human Health
→ The chemical substances which remove the excess acid in gastric juice and raise the pH to an appropriate level in stomach are called antacids. The most commonly used antacids are weak bases such as Sodium bicarbonate [Sodium Hydrogen Carbonate, NaHCO3], magnesium hydroxide [Mg(OH)2] and aluminium hydroxide [Al(OH)3].
→ Generally liquid antacids are more effective than tablets because they have more surface area available for interaction and neutralisation of acid. Milk is a weak antacid. Antacids are commonly taken to relieve heart burn, which is a common symptom of gastritis or acidity. The stomach produces gastric acid to aid digestion.
→ This acid is mainly composed of hydrochloric acid. Excessive secretion of the acid can lead to stomach disorders such as gastritis, gastric ulcers and peptic ulcers disease. These disorders can be treated by antacids, which reduce the amount of acid in the stomach. Antacids contain weak bases that neutralize the acid in the stomach by reacting with them chemically to produce salt and water.
→ For example sodium hydrogen carbonate reacts with hydrochloric acid to give sodium chloride and water. However, antacids provide only temporary relief as they act on the symptoms alone and not on the cause of gastritis. Hence, their effect can wear off quickly and they have to be taken continually to obtain relief.
→ Excessive hydrogen carbonate can make the stomach alkaline and trigger the production of even more acid. Thus, two antacids drugs are designed namely cimetidine and ranitidine which are helpful in treatment of acidity. Recently, omaprazole and lansoprazole are also synthesised. Structure of some antacids are as follows: