Pharmacology for Dentistry

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

1. 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.


2. 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.


3. 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.


4. In organophosphorus poisoning:
   Atropine is used in mushroom
   poisoning due to muscarine.


5. On CVS: Atropine is used for
   counteracting bradycardia and partial

heart block in some patients of

myocardial infarction.

6. 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