page117
companies,
see p.
988),
and propafenone,
see above
under Supraventricular and Ventricular Arrhythmias.
Mexiletine is available from ‘special-order’
manufac-
turers or specialist importing companies (see p.
988) for
treatment of life-threatening ventricular arrhythmias.
LIDOCAINE HYDROCHLORIDE
(Lignocaine hydrochloride)
Indications
ventricular arrhythmias,
especially after
myocardial infarction;
eye (section 11.7);
local
anaesthesia (section 15.2)
Cautions
lower doses in congestive cardiac failure and
following cardiac surgery;
monitor ECG and have
resuscitation facilities available; elderly; interactions:
Appendix 1 (lidocaine)
Contra-indications
sino-atrial disorders,
all grades of
atrioventricular block,
severe myocardial depression;
acute porphyria (section 9.8.2)
Hepatic impairment
caution—increased risk of side-
effects
Renal impairment
possible accumulation of lidocaine
and active metabolite;
caution in severe impairment
Pregnancy
crosses the placenta but not known to be
harmful in
animal
studies—use if benefit outweighs
risk
Breast-feeding
present in milk but amount too small
to be harmful
Side-effects
dizziness,
paraesthesia,
or drowsiness
(particularly if injection too rapid);
other CNS effects
include confusion, respiratory depression and con-
vulsions;
hypotension and bradycardia (may lead to
cardiac arrest);
rarely
hypersensitivity reactions
including anaphylaxis
Dose
. By intravenous injection,
in patients without gross
circulatory impairment, 100 mg as a bolus over a few
minutes (50 mg in lighter patients or those whose
circulation is severely impaired), followed immedi-
ately by
infusion of 4 mg/minute for 30 minutes,
2 mg/minute for 2 hours,
then 1 mg/minute;
reduce
concentration further if infusion continued beyond 24
hours (ECG monitoring and specialist advice for
infusion)
Note
Following
intravenous injection
lidocaine has a short
duration of action (lasting for 15–20 minutes). If an
intra-
venous infusion
is not immediately available the initial
intravenous injection
of 50–100 mg can be repeated if
necessary once or twice at intervals of not less than 10
minutes
Lidocaine
(Non-proprietary) A
Injection 1%
, lidocaine hydrochloride 10 mg/mL, net
price 2-mL amp = 21p; 5-mL amp = 26p; 10-mL amp
= 39p; 20-mL amp = 78p
Injection 2%
, lidocaine hydrochloride 20 mg/mL, net
price 2-mL amp = 32p; 5-mL amp = 31p; 10-mL amp
= 60p; 20-mL amp = 80p
Infusion
,
lidocaine hydrochloride 0.1% (1 mg/mL)
and 0.2% (2 mg/mL) in glucose intravenous infusion
5%.
500-mL containers
Minijet
c
Lignocaine
(UCB Pharma) A
Injection
,
lidocaine hydrochloride 1% (10 mg/mL),
net price 10-mL disposable syringe = £8.48;
2%
(20 mg/mL),
5-mL disposable syringe = £8.18
2.4
Beta-adrenoceptor
blocking drugs
Beta-adrenoceptor blocking drugs (beta-blockers) block
the beta-adrenoceptors in the heart,
peripheral
vascu-
lature,
bronchi, pancreas,
and liver.
Many beta-blockers are now available and in general
they are all equally effective. There are, however, differ-
ences between them,
which may affect choice in treat-
ing particular diseases or individual patients.
Intrinsic sympathomimetic activity (ISA, partial agonist
activity)
represents
the capacity of
beta-blockers
to
stimulate as
well
as
to block adrenergic receptors.
Oxprenolol,
pindolol,
acebutolol,
and
celiprolol
have intrinsic sympathomimetic activity;
they tend to
cause less bradycardia than the other beta-blockers and
may also cause less coldness of the extremities.
Some beta-blockers are lipid soluble and some are water
soluble.
Atenolol,
celiprolol,
nadolol,
and sotalol
are
the most water-soluble;
they are less likely to enter the
brain,
and may therefore cause less sleep disturbance
and
nightmares.
Water-soluble
beta-blockers
are
excreted by the kidneys and dosage reduction is often
necessary in renal impairment.
Beta-blockers with a relatively short duration of action
have to be given two or three times daily. Many of these
are, however, available in modified-release formulations
so that administration once daily is adequate for hyper-
tension.
For
angina twice-daily treatment
may some-
times be needed even with a modified-release formula-
tion.
Some beta-blockers,
such as atenolol,
bisoprolol,
carvedilol,
celiprolol,
and nadolol,
have an intrinsically
longer duration of action and need to be given only once
daily.
Beta-blockers slow the heart and can depress the myo-
cardium;
they are contra-indicated in patients
with
second-
or
third-degree
heart
block.
Beta-blockers
should also be avoided in patients
with worsening
unstable heart
failure;
care is required when initiating
a beta-blocker in those with stable heart failure (see also
section 2.5.5). Sotalol may prolong the QT interval, and
it occasionally causes life-threatening ventricular arrhy-
thmias (important: particular care is required to avoid
hypokalaemia in patients taking sotalol).
Labetalol,
celiprolol,
carvedilol,
and nebivolol
are
beta-blockers that have,
in addition,
an arteriolar vaso-
dilating action,
by diverse mechanisms,
and thus lower
peripheral
resistance.
There is no evidence that
these
drugs have important advantages over other beta-block-
ers in the treatment of hypertension.
Beta-blockers can precipitate bronchospasm and should
therefore usually be avoided in patients with a history of
asthma. When there is no suitable alternative, it may be
necessary for a patient with well-controlled asthma,
or
chronic obstructive pulmonary disease (without signifi-
cant
reversible airways obstruction),
to receive treat-
ment with a beta-blocker for a co-existing condition (e.g.
heart failure or following myocardial infarction).
In this
situation,
a
cardioselective
beta-blocker
should
be
selected and initiated at a low dose by a specialist;
the
patient should be closely monitored for adverse effects.
Atenolol,
bisoprolol,
metoprolol,
nebivolol,
and (to a
lesser extent) acebutolol,
have less effect on the beta
2
(bronchial) receptors and are,
therefore,
relatively
car-
BNF 61
2.4 Beta-adrenoceptor blocking drugs
97
2
Cardiovascular system