Pharmacological terms
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.
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