used intravenously for the treatment of hypertension
particularly in the peri-operative period.
Beta-blockers can be used to control the pulse rate in
children withphaeochromocytoma. However, they should
never be used alone as beta-blockade without concurrent
alpha-blockade may lead to a hypertensive crisis;
phenoxybenzamine hydrochloride p. 117 should always be
used together with the beta-blocker.
Arrhythmias
In arrhythmias, beta-blockers act principally by attenuating
the effects of the sympathetic system on automaticity and
conductivity within the heart. They can be used alone or in
conjunction with digoxin p. 81 to control the ventricular rate
inatrialfibrillation. Beta-blockers are also useful in the
management ofsupraventricular tachycardiasandventricular
tachycardiasparticularly to prevent recurrence of the
tachycardia.
Esmolol hydrochloride is a relatively cardioselective beta-
blocker with a very short duration of action, used
intravenously for the short-term treatment of
supraventricular arrhythmias and sinus tachycardia,
particularly in the peri-operative period.
Sotalol hydrochloride is a non-cardioselective beta-
blocker with additional class III anti-arrhythmic activity.
Atenololand sotalol hydrochloride suppress ventricular
ectopic beats and non-sustained ventricular tachycardia.
However, the pro-arrhythmic effects of sotalol
hydrochloride, particularly in children with sick sinus
syndrome, may prolong the QT interval and induce torsade
de pointes.
Heart failure
Beta-blockers may produce benefit in heart failure by
blocking sympathetic activity and the addition of a beta-
blocker such as carvedilol to other treatment for heart failure
may be beneficial. Treatment should be initiated by those
experienced in the management of heart failure.
Thyrotoxicosis
Beta-blockers are used in the management ofthyrotoxicosis
including neonatal thyrotoxicosis; propranolol
hydrochloride p. 104 can reverse clinical symptoms within
4 days. Beta-blockers are also used for the pre-operative
preparation for thyroidectomy; the thyroid gland is rendered
less vascular, thus facilitating surgery.
Other uses
In tetralogy of Fallot, esmolol hydrochloride or propranolol
hydrochloride may be given intravenously in the initial
management ofcyanotic spells; propranolol hydrochloride is
given by mouth for preventing cyanotic spells. If a severe
cyanotic spell in a child with congenital heart disease
persists despite optimal use of 100 % oxygen, propranolol
hydrochloride is given by intravenous infusion. If cyanosis is
still present after 10 minutes, sodium bicarbonate p. 586
intravenous infusion is given in a dose to correct acidosis (or
dose calculated according to arterial blood gas results);
sodium bicarbonate 4. 2 % intravenous infusion is appropriate
for a child under 1 year and sodium bicarbonate 8. 4 %
intravenous infusion in children over 1 year. If blood-glucose
concentration is less than 3 mmol/litre, glucose 10 %
intravenous infusion is given, followed by intravenous or
intramuscular injection of morphine p. 282.
Beta-blockers are also used in theprophylaxis of migraine.
Betaxolol p. 682 , levobunolol hydrochloride p. 682 , and
timolol maleate p. 683 are used topically inglaucoma.
Beta-adrenoceptor blockers f
(systemic)
lCONTRA-INDICATIONSAsthma.cardiogenic shock.
hypotension.marked bradycardia.metabolic acidosis.
phaeochromocytoma (apart from specific use with alpha-
blockers).second-degree AV block.severe peripheral
arterial disease.sick sinus syndrome.third-degree AV
block.uncontrolled heart failure
CONTRA-INDICATIONS, FURTHER INFORMATION
▶BronchospasmBeta-blockers, including those considered to
be cardioselective, should usually be avoided in patients
with a history of asthma, bronchospasm or a history of
obstructive airways disease. However, when there is no
alternative, a cardioselective beta-blocker can be given to
these patients with caution and under specialist
supervision. In such cases the risk of inducing
bronchospasm should be appreciated and appropriate
precautions taken.
lCAUTIONSDiabetes.first-degree AV block.history of
obstructive airways disease (introduce cautiously).
myasthenia gravis.portal hypertension (risk of
deterioration in liver function).psoriasis.symptoms of
thyrotoxicosis may be masked
lSIDE-EFFECTS
▶Common or very commonAbdominal discomfort.
bradycardia.bronchospasm.confusion.constipation.
depression.diarrhoea.dizziness.dry eye (reversible on
discontinuation).dyspnoea.erectile dysfunction.fatigue
.headache.heart failure.hyperglycaemia.hyperhidrosis.
hypoglycaemia.hypoglycaemia masked.nausea.
paraesthesia.peripheral coldness.peripheral vascular
disease.postural hypotension.rash (reversible on
discontinuation).sleep disorders.syncope.visual
impairment.vomiting
▶UncommonAtrioventricular block.dry mouth.skin
reactions.urinary disorders
▶Rare or very rareAlopecia.hallucination.psoriasis
exacerbated.thrombocytopenia
SIDE-EFFECTS, FURTHER INFORMATION
BradycardiaWith administration by intravenous
injection, excessive bradycardia can occur and may be
countered with intravenous injection of atropine sulfate.
OverdoseTherapeutic overdosages with beta-blockers
may cause lightheadedness, dizziness, and possibly
syncope as a result of bradycardia and hypotension; heart
failure may be precipitated or exacerbated. For details on
the management of poisoning, see Beta-blockers, under
Emergency treatment of poisoning p. 832.
lALLERGY AND CROSS-SENSITIVITYCaution is advised in
patients with a history of hypersensitivity—may increase
sensitivity to allergens and result in more serious
hypersensitivity response. Furthermore beta-adrenoceptor
blockers may reduce response to adrenaline (epinephrine).
lPREGNANCYBeta-blockers may cause intra-uterine
growth restriction, neonatal hypoglycaemia, and
bradycardia; the risk is greater in severe hypertension.
lBREAST FEEDINGWith systemic use in the mother, infants
should be monitored as there is a risk of possible toxicity
due to beta-blockade. However, the amount of most beta-
blockers present in milk is too small to affect infants.
lMONITORING REQUIREMENTSMonitor lung function (in
patients with a history of obstructive airway disease).
lTREATMENT CESSATIONAvoid abrupt withdrawal.BNFC 2018 – 2019 Hypertension 103
Cardiovascular system2