164 Section 3/ Drugs Acting on ANS
of one to two hours until a satisfactory
response is obtained. For urinary retention
catheterization can be done and patients is
kept in dark room to alleviate photophobia.
Therapeutic Uses
- Gastrointestinal colic (as antispas-
modic): Belladonna alkaloids relax the
spasm of smooth muscles of intestinal,
urinary and biliary tract. They are also
effective in functional and drug
induced diarrhoea, to relieve urinary
urgency and frequency and enuresis in
children. They are also used to reduce
gastric secretion in peptic ulcer
patients. Also, used to reduce the
excessive sweating in tuberculosis and
sweating and salivation in parkinso-
nian patients. - CNS disorders: Scopolamine and
hyoscine are effectively used in the
treatment of nausea, vomiting and motion
sickness. Centrally acting anticholinergic/
antihistaminics e.g. trihexyphenidyl are
used in parkinsonism. - Pre-anaesthetic medication: These
agents reduce the salivary and respi-
ratory secretion and are administered
half an hour before general anaesthe-
sia. They also prevent laryngospasm.
Atropine is given in combination with
morphine as a preanaesthetic medi-
cation to antagonize the central
depressant action of morphine on
respiration. - In organophosphorus poisoning:
Atropine is used in mushroom
poisoning due to muscarine. - On CVS: Atropine is used for
counteracting bradycardia and partial
heart block in some patients of
myocardial infarction.
- As mydriatic and cycloplegic
agent: Atropine is used to produce
mydriasis and cycloplegia for test-
ing errors of refraction. Mydriasis is
required for fundoscopic examina-
tion and in the treatment of iritis
and keratitis.
ANTIMUSCARINICS (SEMISYNTHETIC AND
SYNTHETIC)
HOMATROPINE
More potent than atropine. Used in
eye and onset of mydriasis and
cycloplegia is similar to that of atropine
but homatropine is not much used for
producing cycloplegia.
CYCLOPENTOLATE
It is more potent and rapidly acting as
compared to homatropine for producing
mydriasis and cycloplegia especially in
children. It is also used in iritis.
TROPICAMIDE
It is used for refraction testing in adults
and as mydriating agent for fundoscopy. It
has quickest and briefest action.
ATROPINE METHONITRATE
It is used for abdominal colic and in
aerosol form it is used in bronchial asthma.
IPRATROPIUM BROMIDE
It is a valuable drug used in the treatment
of chronic obstructive pulmonary disease