" Important Medicines or Drugs "
" Chemicals which may be used for the treatment of diseases and for reducing the suffering
from pain are called medicines or drugs.
" The branch of science which makes use of chemicals for the treatment of diseases
(therapeutic effect) is called chemotherapy.
Some important classes of drugs are:-
1. Antacid :
The chemical substances which neutralize the excess acid in gastric juice and raise the pH to
an appropriate level in stomach are 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 acid.
Milk is a weak antacid.
Histamine stimulates the secretion of pepsin and hydrochloric acid. The drug cimetidine
[Tegamet] was designed to prevent the interaction of histamine with the receptors present in
the stomach. Cimetidine binds to the receptors and triggers the release of acid in the stomach.
This results in release of lesser amount of acid. Now ranitidine (zantac), omeprazole and
lansoprazole are used hyperacidity.
2. Tranquilizers (Psychotherapeutic Drugs) :
Chemical substances used for the treatment of stress, anxiety, irritability and mild or even
severe mental diseases are known as tranquilizers. These affect the central nervous system
and induce sleep for the patients as well as eliminate the symptoms of emotional distress.
They are the common constituents of sleeping pills.
Noradrenaline is one of the neurotransmitter that plays a role in mood change. If the level of
noradrenaline is low, the signal sending activity becomes low, and the person suffers from
depression. In such situations antidepressant drugs are required. These drugs inhibit the
enzymes which catalyse the degradation of noradrenaline. If the enzyme is inhibited, this
important neurotransmitter is slowly metabolized and can activate its receptor for longer periods of time, thus counteracting the effect of depression. Iproniazid and phenelzine are
two such drugs.
Barbituric acid and its derivatives viz. veronal, amytal, nembutal, luminal, seconal are known
as barbiturates. Barbiturates are hypnotic, i.e., sleep producing agents.
Equanil is used to control depression and hypertension.
Non-hypnotic chlorodiazepoxide and meprobamate are relatively mild tranquilizers suitable
for relieving tension.
3. Analgesics :
Medicines used for getting relief from pain are called analgesics. These are of two types :
i. Narcotics :
Drugs which produce sleep and unconsciousness are called narcotics. These are habit forming
drugs. For example, morphine and codeine. Morphine diacetate is commonly known as
heroin.
ii. Non-narcotics :
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 (2-acetoxybenzoic acid) is most
commonly used analgesic with antipyretic properties. Now these days because of its antiblood clotting action, aspirin is widely used to treat heart-attacks.
Aspirin is toxic for liver and sometimes also causes bleeding from- stomach. So, naproxen,
ibuprofen, paracetamol, dichlorophene sodium are other widely used analgesics.
4. Antipyretics :
These are the chemical substance which reduce body temperature during high fever.
Paracetamol, aspirin, phenacetin (4-hydroxy acetanilide), analgin and novalgin, etc. are
common antipyretics. Out of these, paracetamol (4-acetamidophenol) is most common.
5. Antimicrobials :
An antimicrobial tends to kill or prevent development of microbes CII inhibit the pathogenic
action of microbes such as bacteria, fungi and virus selectively.
[Sulpha drugs constitute a group of drugs which are derivatives of sulphanilamide and have
great antimicrobial capacity, thus, these are widely used against diseases such as dyptheria,
dysentry, tubercu losis, etc.]
6. Antibiotics :
These are the substances (produced wholly or partially by chemical synthesis) which in low
concentrations inhibit the growth of microorganisms or destroy them by intervening in their
metabolic processes.
Antibiotics are products of microbial growth and thus, antibiotic therapy has been likened to
setting “one thief against another”.
Antibiotics are of two types :
i. Bactericidal antibiotics have cidal (killing) effect on microbes. For example,
penicillin, ofloxacin, amino glycosides, etc.
ii. Bacteriostatic antibiotics have astatic (inhibitory) effect on microbes. For example,
erythromycin, tetracycline, chloramphenicol, etc.
Penicillin was the first antibiotic discovered (by Alexander Fleming) in 1929. It is a narrowspectrum antibiotic. Ampicillin and amoxicillin are semi-synthetic Modifications of
penicillin.
Penicillin is not suitable to all persons and some Persons are allergic to it. Consequently, it is
essential to test the patients for sensitivity (or allergy) to penicillin, before it is administered.
In India, penicillin is manufactured at Pimpri and Rishikesh (Uttarakhand).
Broad-spectrum antibiotics are effective against different types of harmful microorganisms.
e.g. Tetracycline, chloramphenicol in case of typhoid, dysentery, fever ofloxacin etc.
7. Antiseptics :
These are the chemicals which either kill or prevent the growth of microorganisms.
Antiseptics are applied to the living tissues such wounds, cuts, ulcers and skin diseases in the
form of antiseptic creams like furacin and soframycin. Some important examples of
antiseptics are-
(i) Dettol is a mixture of chloroxylenol and terpineol.
(ii) Bithional is added to soaps to impart antiseptic properties to reduce the odours produced
by bacterial organic matter on the skin.
(iii) Tincture of iodine is a 2-3% solution of iodine in alcohol, which is a powerful antiseptic
for wounds.
(iv) Iodoform (CHI3) is also used as an antiseptic for wounds.
(v) Boric acid in dilute aqueous solution is weak antiseptic.
8. Disinfectants :
These are the chemical substances which kill microorganisms not safe to be applied to the
living tissues. They are generally kill the microorganisms present on inanimate objects such
as drainage systems, instruments, etc.
Some common examples of disinfectants are as follows :
(i) 1% phenol solution is disinfectant while in lower concentration 0.2% solution of phenol is
antiseptic.
(ii) 0.2-0.4 ppm aqueous solution of chlorine is used for sterilisation of water to make it fit
for drinking purpose.
(iii) SO2 at very low concentrations behaves like disinfectant.
(iv) Formaldehyde (HCHO) in the disinfecting rooms and operation gaseous theatres forms
is used in hospitals.
9. Antifertility Drugs :
These are the chemical substances used to control the pregnancy. These are also called oral
contraceptives. They belong to the class of natural products, known as steroids.
Birth control pills essentially contain a mixture of synthetic estrogen and progesterone
derivatives. Norethindrone is widely used as antifertility drug
Artificial Sweetening Agents :
Sucrose (table sugar) and fructose are the most widely used natural sweeteners. But they add
to our calorie intake and promote tooth decay. To avoid these problems many people take
artificial sweeteners.
Organic substances which have been synthesized in lab are known to be many times sweeter
than cane sugar. Such compounds are known as artificial sweetening agents or artificial
sweeteners.
Some important artificial sweeteners are given below :
(i) Saccharin (Ortho sulphobenzimide) :
• Discovered by Johns- Hopkins in 1879 (University of USA).
• It is the most popular artificial sweetener. It is 550 times as sweet as cane Sugar, since it
is insoluble in water, so it is sold in the market as its soluble or calcium salt state.
• It is non-biodegradable so excreted from the body in urine (unchanged). Its use is of great
value for diabetic persons and people who need to control intake of calories.
(ii) Aspartame :
• It is the methyl ester of the dipeptide derived from phenylalanine aspartic acid. It is
also known as “Nutra sweet”.
• It decomposes at baking or cooking temperatures and hence, can used only in cold food
and soft drinks.
• Aspartame has the same amount of calories as sugar (4 cal per gram).
• Aspartame should not be used by people suffering from the genetic disease known as
PKU (phenyl ketone urea). Because in such people decomposition of aspartame gives
phenyl pyruvic acid. Accumulation of phenyl pyruvic acid is harmful especially to infants
due to brain damage and mental retardation.
(iii) Alitame :
It is quite similar to aspartame but more stable than aspartame. It is 2000 times as sweet as
sucrose. The main problem for such sweetener is the control of sweetness of the substance to
which it is added because it is high potency sweetener.
(iv) Sucralose :
It is a trichloro derivative of sucrose. It’s appearance and taste are like sugar. It is stable at
cooking temperature. It is almost 600 times as sweet as sucrose. However, it neither provides
calories nor causes tooth decay.
(v) Cyclamate :
It is N-cyclohexyl sulphamate. It is only 20 times sweeter than cane sugar.
Food Preservatives :
These are the chemical substances added to food to prevent their spoilage due to microbial
growth (bacteria, yeasts and moulds) and to retain their nutritive value for longer periods .
The most commonly used preservatives include table salt, sugar, vegetable oil, vinegar,
citric acid, spices and sodium benzoate (C6H5COONA). Salts of sorbic acid and propanoic
acid are also used as preservatives for cheese, baked food, pickles, meat and fish products.
1. Sodium benzoate is metabolised by conversion into hippuric acid
(C6H5CONHCH2COOH), which is ultimately excreted through urine. It is used in soft
drinks and acidic foods.
2. Antioxidants like BHT (butylated hydroxytoluene) and BRA (Butylated hydroxyanisole)
retard the action of oxygen on the food and help in the preservation of food materials.
