478
P A R T 5
Drugs acting on the autonomic nervous system
occur with propranolol. These drugs are all excreted in
the urine.
Contraindications and cautions
Non-selective beta-adrenergic blocking agents are con-
traindicated in the presence of allergy to any of these
drugs or any components of the drug being used
to
avoid hypersensitivity reactions
; with bradycardia or
heart blocks, shock or HF,
which could be exacerbated
by the cardiac-suppressing effects of these drugs
; with
bronchospasm, chronic obstructive pulmonary disease
(COPD) or acute asthma,
which could worsen due to
the blocking of the sympathetic bronchodilation
; with
pregnancy
because teratogenic effects have occurred in
animal studies with all of these drugs except sotalol and
because neonatal apnoea, bradycardia and hypoglycae
mia could occur
; and with breastfeeding
because of the
potential effects on the neonate, which could include
slowed heart rate, hypotension and hypoglycaemia.
The safety and efficacy for use of these drugs in children
have not been established.
These drugs should be used cautiously in individ-
uals with diabetes and hypoglycaemia
because of the
blocking of the normal signs and symptoms of hypo
glycaemia and hyperglycaemia
; with thyrotoxicosis
because of the adrenergic blocking effects on the thyroid
gland
; or with renal or hepatic dysfunction,
which could
interfere with the excretion and metabolism of these
drugs.
Adverse effects
People receiving these drugs often experience adverse
effects
related to blockage of beta-receptors in the SNS.
CNS effects include headache, fatigue, dizziness, depres-
sion, paraesthesias, sleep disturbances, memory loss
and disorientation. Cardiovascular effects can include
bradycardia, heart block, HF, hypotension and periph-
eral vascular insufficiency. Pulmonary effects can range
from difficulty breathing, coughing and bronchospasm
to severe pulmonary oedema and bronchial obstruction.
GI upset, nausea, vomiting, diarrhoea, gastric pain and
even colitis can occur as a result of unchecked parasym-
pathetic activity and the blocking of the sympathetic
receptors. Genitourinary effects can include decreased
libido, impotence, dysuria and Peyronie’s disease.
Other effects that can occur include decreased exercise
TABLE 31.4
DRUGS IN FOCUS Non-selective beta-adrenergic blocking agents
Drug name
Dosage/route
Usual indications
nebivolol (Nebilet)
Initially 5 mg/day PO, increase at 2-week
intervals based on person’s response;
maximum dose 10 mg/day
Treatment of hypertension, alone or as part
of combination therapy in adults
oxprenolol (Corbeton)
20-40 mg PO b.d. or t.d.s.; up to 320 mg daily
depending on individual response
Treatment of angina pectoris, cardiac
arrhythmias, hypertension
pindolol (Visken)
Initially 5 mg PO b.d., to a maximum of
60 mg/day PO
Treatment of hypertension in adults
propranolol (Inderal)
Dose varies widely based on indication; check
drug guide for specific information
Treatment of hypertension, angina,
idiopathic hypertrophic subaortic stenosis
(IHSS)–induced palpitations, angina and
syncope, certain cardiac arrhythmias
induced by catecholamines or digoxin,
phaeochromocytoma; prevention of
reinfarction after MI; prophylaxis for
migraine headache (which may be
caused by vasodilation and is relieved
by vasoconstriction, although the
exact action is not clearly understood);
prevention of stage fright (which is
a sympathetic stress reaction to a
particular situation); and treatment of
essential tremors
sotalol (Cardol, Sotacor)
160 mg/day PO in two divided doses. Usual
range 160–320 mg/day PO
Treatment of potentially life-threatening
ventricular arrhythmias; maintenance of
normal sinus rhythm in people with atrial
fibrillation/flutter
timolol (Nyogel, Tenopt)
10 mg PO b.d., increases based on person’s
response; 1–2 drops (gtt) in affected eye(s)
for glaucoma
Treatment of hypertension; prevention
of reinfarction after MI; prophylaxis for
migraine; in ophthalmic form, reduction
of intraocular pressure in open-angle
glaucoma
