Section II. ANTICHOLINERGIC (PARASYMPATHOLYTIC) DRUGS
ATROPINE AS THE STANDARD ANTICHOLINERGIC DRUG
Atropine is the best known of the anticholinergic or parasympatholytic drugs,
which inhibit the parasympathetic nervous system. Atropine is an extremely poisonous
drug derived from a plant called belladonna. A tincture, an extract, and a leaf fluid
extract are still official drugs. Their therapeutic value lies chiefly in their atropine
a. Effects. Small doses of atropine cause bradycardia (slow heartbeat), and
larger doses cause tachycardia (fast heartbeat). Atropine relaxes all smooth muscles
(for example, the muscles lining the intestines) except those of the blood vessels. It
decreases the rate of secretion of glands of the respiratory tract, gastric glands,
salivary glands, and some sweat glands.
b. Adverse Effects. The side effects of atropine and other parasympatholytics
may include dry mouth, blurred vision, fatigue, light- headedness, and dizziness. Older
men may suffer urinary retention. These effects may limit the amount of these drugs,
which can be given chronically. However, extremely dangerous reactions from normal
doses of these drugs are rare with adults, but more frequent with children. Very large
doses tend to cause sedation, a disturbed mental state, and even respiratory
depression and convulsions. Some clients may acquire a dry, flushed skin, and a high
body temperature, which is very dangerous in children.
c. Uses. Atropine and other parasympatholytics have been frequently used in
the treatment of peptic ulcer, which they ameliorate by reducing acid secretions in the
stomach when it is empty and by decreasing the strength of smooth muscle
contractions. They are also used to treat some other GI disturbances, which are not
associated with organic disease--diarrhea, belching, spasm of the pylorus (opening
through which the stomach empties into the intestine), and "stomach ache" because of
overactivity of the GI smooth muscles. These drugs also relieve cystitis (bladder
inflammation) by relaxing smooth muscles of the bladder. These drugs are used in the
eye to dilate it and to paralyze accommodation (that is, temporarily prevent the eye
from focusing). Atropine is sometimes used to counteract some of the effects of
cholinergic drugs during or after their use in therapy. One significant use of atropine in
the military is to counteract the effects of nerve gas. Atropine is used preoperatively to
decrease the amount of saliva and respiratory secretions, especially when an
inhalation anesthetic is to be used.
d. Contraindications. A client with glaucoma should never be given a
parasympatholytic, except for small doses such as those given just before anesthesia.
These drugs should not be given to clients over 35 with a shallow anterior chamber
(between the cornea and the lens of the eye). These drugs are not necessary for eye
dilation in routine eye examinations. Sympathomimetics are better for this purpose.