Pharmacological terms used for drugs acting on various systems

1. Drugs acting on mouth and salivary glands

a. Sialogogues / Sialics: These are drugs which increase the secretion of saliva. They may act either directly upon the gland or their secreting nerves or may act reflexly.

i.              Direct sialogogues: Eg. Pilocarpine, Physostigmine.

ii.            Reflexly acting sialogogues: Eg. Alcohol, Acids, Bitters and Aromatics. Through sensory nerve ending in the mouth or through the stomach. Eg. Ipecacuanha, Antimony.

b. Antisialics: are drugs which diminish the secretion of saliva.

i.              By paralysing secretary nerve endings. Eg. Atropine

ii.             Acting by decreasing irritation of the buccal mucous membrane. Eg. Demulcents – are substances which have the property of protecting mucous membrane when these are irritated or inflammed. Eg. Syrup, Honey mucillages, Linseed tea.

2. Drugs acting on Stomach and Intestine

a. Stomachics: are drugs which increase the flow of gastric juice. Alcohol and bitters stimulate the gastatory nerves in the tongue and reflexely increase the gastric juice and this increase the appetite. Eg. Gentian, Calamba, Mustard, Ginger.

b. Gastric stimulants: include the drugs, which produce slight irritation of the gastric mucosa and this increase the vascularity of the stomach. Most of them act as emetics if given in large doses.

c. Gastric sedatives: reduce gastric pain, control vomiting. Eg. Ice and Bismuth act locally and Morphine act centrally.

d. Gastric tonics: these act by increasing the acidity of the chyme, stimulate the movement of the stomach. Eg. Dil. HCl, Dil. HNO3.

e. Neuromuscular gastric stimulants: these increase the tone of gastric muscles and this stimulate the movement of the stomach.

f. Carminatives: are drugs ahich assist the expulsion of gases from the stomach and intestines. Eg. Turpentine, Aromatic spirit of ammonia, cardamoum.

g. Emetics: are agents which produce vomiting. Some of the emetics act locally by irritating the sensory nerve ending while others produce emesis directly stimulating the vomiting centre. Even saturated common salt can act as local emetic. Apomorphine act centrally.

h. Anti emetics: are agents which prevent vomiting. Some of the anti emetics act locally by reducing the irritation of the sensory nerve ending Eg. Demulcents or by acting centrally on Chemoreceptor trigger zone (CTZ) or on vomiting centre. Eg. Domperidone.

i. Antacids: They correct excessive acidity of the ingesta. Eg. Alkalies such as lime water.

j. Gastric antiseptics: are used in ruminants to control excessive fermentation in rumen. These are also called as antizymotics. Eg. Oil of turpentine.

k. Purgatives or Cathartics: Cause evacuation of the intestinal contents.

l. Intestinal astringents: are agents, which limit the action of the bowel and correct excessive fluidity of the intestinal contents. Some act as vascular astringents by contracting the intestinal blood vessels and lessening the amount of fluid excreted. Eg. Lead salts. Others lessen peristaltic movement of the intestine. Eg. Opium.

            Some drugs because of their antacid nature check excessive action of the intestine by eliminating the acidity of the intestine. Some others because of the insolubility forms a coating over the intestinal mucous membrane and protect it from further irritation. Certain drugs because of their tannic acid content coagulate protein, which forms a protective covering over the intestinal mucosa.

m. Intestinal antiseptic: These agents diminsh activity of the bacteria in the intestine. They are sometimes prescribed in diarrhoea and allied condition which are believed to be due to the presence of pathogenic bacteria. Eg. Carbolic acid, Oil of Turpentine. Etc.

n. Cholagogues: These agents increase the expulsion of bile. Bile itself act as a direct cholagogue. Eg. Ox bile (Direct cholagogue). Indirect cholagogue – some of the purgatives by increasing the intestinal action reduce the absorption of bile and reflexely stimulate the contraction of gall bladder and bile duct. They are frequently prescribed in disorders of bile.

3. Drugs acting on Uro-genital tract

a. Diuretics: Increase the flow of urine. Potassium nitrate, which increases the fluidity of the blood by raising the osmotic tension of the plasma, attracting water from the tissue fluid. This increased blood volume and the excess fluid filtered by the glomeruli and reabsorption from the tubule is prevented by the presence of saline. Some volatile oils produce diuresis by causing dilation of the renal vessels. Eg. Oil of Turpentine. Some others increase the blood flow through the kidneys by its action on the heart. Eg. Digitalis.

b. Vesical sedatives: relieve the irritability of the bladder. They are represented by alkalies like Sodium bicarbonate.

c. Lithotropic: are agents, which prevent the deposition of solids from the urine or promoting their removal.

d. Urinary antiseptics: are agents which prevent multiplication of organisms in urine, mucosa of the bladder and urinary passages. Eg. Benzoic acid.

e. Aphrodisiacs: increase sexual desire by increasing general body viguor. Eg. Strychnine, Yohimbine exert their action by causing a vascular congestion of genital organs.

f. Anaphrodisiacs: diminish sexual desire. Eg. General sedatives like Pot. Bromide.

g. Galactagogues: are agents which are believed to increase the milk secretion.

h. Antigalactagogues: Some of the drugs paralysing the termination of all nerves supplying secretory glands may produce an action on the mammary gland. Eg. Belladonna.

4. Drugs acting on cardio vascular system

a. Vasoconstrictors: are agents which cause constriction of walls of the blood vessels and diminish their calibre. Arterioles are specially affected by such drugs. Eg. Adrenalin.

b. Vasodilators: are agents which cause dilatation of the peripheral arterioles by relaxation of the unstripped muscles in them. Eg. Amyl nitrate.

c. Cardiac stimulants: cause a more forcible heart beat which might be due to a direct action on the heart muscle or indirectly by raising the blood pressure. Eg. Caffeine, Digitalis.

d. Cardiac depressants: diminish the force of cardiac contraction and lessens the frequency of heart beat. Eg. Quinine.

e. Haematinics: improve the quality of the blood by increasing the number of RBCs and the amount of Hb. Eg. Iron salts.

5. Drugs acting on respiratory system

a. Expectorants: cause an increase of bronchial secretion and render the secretions more fluidy and thus facilitates its expulsion. Eg. Pot. Iodide, antimony salts.

b. Respiratory stimulants (Analeptics): are agents, which increase the irritation of the respiratory centre and thus increase the rate and depth of the respiration. Eg. Doxapram.

c. Respiratory sedatives: lessen the irritability of the respiratory centre. Eg. Morphine.

d. Bronchial relaxants: are drugs used to bring about relaxation of the bronchial musculature to relieve bronchial asthma. Eg. Adrenaline.

6. Drugs acting on central nervous system

a. Cerebral stimulants: are agents which cause an overall increase on the functional activity of the cerebrum. Eg. Caffeine.

b. Spinal stimulants: are agents which increase the reflex excitability and conductivity of the spinal cord in medicinal doses. Eg. Strychnine.

c. Narcotics: are drugs which can be used to produce deep sleep which is accompanied by a depression of the circulatory and respiratory mechnaisms. Eg. Barbiturates.

d. Hypnotics / Soporifics: are agents which induce sleep. Eg. Chloral hydrate.

e. Anodynes / Analgesics: are agents employed for the relief of pain. Eg. Morphine.

f. Anaesthetics: are agents used for producing total loss of consciousness so that pain is no longer felt at the same time abolishing the reflex action.

7. Drugs acting on eye:

a. Mydriatics: are drugs which cause dilatation of the pupil. Eg. Atropine.

b. Miotics: are drugs which cause contraction of the pupil. Eg. Pilocarpine.

8. Drugs acting on skin

a. Diaphoretics or sudorifics: are agents which induce sweating. Eg. Ammonia acetate solution.

b. Antidiaphoretics or anhydriotics: agents lessen the secretion of sweat. Eg. Atropine.

c. Counter Irritants: agents which increase the irritability of the applied area there by increase the healing process. Eg. Haematinics, Vesicants, Pustulants and Caustics.

d. Emollients: are agents which reduce the irritability of the applied area. Eg. Vegetable oils.

9. Alteratives: are drugs which bring about favourable change in the process of nutrition and repair especially in the convalescent period. Eg. Iron salt, Pot. Iodide.