There can be variation in the licensing of
different medicines containing the same drug.
Solution for injection
▶Glycopyrronium bromide (Non-proprietary)
Glycopyrronium bromide 200 microgram per
1 ml Glycopyrronium bromide 200micrograms/1ml solution for
injection ampoules | 10 ampoule P £14.00 DT = £9.95 |
10 ampoule P £5.72 DT = £9.95 (Hospital only)
Glycopyrronium bromide 600micrograms/3ml solution for injection
ampoules | 3 ampoule P £8.00 | 10 ampoule P £9.61 DT =
£14.99 (Hospital only) | 10 ampoule P £14.99 DT = £14.99
Neuromuscular blockade
1.1
Neuromuscular blockade
Neuromuscular blocking drugs
Neuromuscular blocking drugs used in anaesthesia are also
known as muscle relaxants. By specific blockade of the
neuromuscular junction they enable light anaesthesia to be
used with adequate relaxation of the muscles of the
Anaesthesia
abdomen and diaphragm. They also relax the vocal cords and
allow the passage of a tracheal tube. Their action differs from
the muscle relaxants used in musculoskeletal disorders that
act on the spinal cord or brain.
Patients who have received a neuromuscular blocking drug
should always have their respiration assisted or controlled
until the drug has been inactivated or antagonised. They
should also receive sufficient concomitant inhalational or
intravenous anaesthetic or sedative drugs to prevent
awareness.
Non-depolarising neuromuscular blocking drugs
Non-depolarising neuromuscular blocking drugs (also
known as competitive muscle relaxants) compete with
acetylcholine for receptor sites at the neuromuscular
junction and their action can be reversed with
anticholinesterases such as neostigmine p. 1188. Non-
depolarising neuromuscular blocking drugs can be divided
into the aminosteroid group, comprising pancuronium
bromide p. 1409, rocuronium bromide p. 1409, and
vecuronium bromide p. 1409, and the
benzylisoquinolinium group, comprising atracurium
besilate p. 1407, cisatracurium p. 1408, and mivacurium
p. 1408.
Non-depolarising neuromuscular blocking drugs have a
slower onset of action than suxamethonium chloride
p. 1407. These drugs can be classified by their duration of
action as short-acting (15–30 minutes), intermediate-acting
(30–40 minutes), and long-acting (60–120 minutes),
although duration of action is dose-dependent. Drugs with a
shorter or intermediate duration of action, such as
atracurium besilate and vecuronium bromide p. 1409, are
more widely used than those with a longer duration of
action, such as pancuronium bromide.
Non-depolarising neuromuscular blocking drugs have no
sedative or analgesic effects and are not considered to trigger
malignant hyperthermia.
For patients receiving intensive care and who require
tracheal intubation and mechanical ventilation, a non-
depolarising neuromuscular blocking drug is chosen
according to its onset of effect, duration of action, and side-
effects. Rocuronium bromide, with a rapid onset of effect,
may facilitate intubation. Atracurium besilate or
cisatracurium may be suitable for long-term neuromuscular
blockade since their duration of action is not dependent on
elimination by the liver or the kidneys.
Atracurium besilate, a mixture of 10 isomers, is a
benzylisoquinolinium neuromuscular blocking drug with an
intermediate duration of action. It undergoes non-enzymatic
metabolism which is independent of liver and kidney
function, thus allowing its use in patients with hepatic or
renal impairment. Cardiovascular effects are associated with
significant histamine release; histamine release can be
minimised by administering slowly or in divided doses over
at least 1 minute.
Cisatracurium is a single isomer of atracurium besilate. It
is more potent and has a slightly longer duration of action
than atracurium besilate and provides greater cardiovascular
stability because cisatracurium lacks histamine-releasing
effects.
Mivacurium, a benzylisoquinolinium neuromuscular
blocking drug, has a short duration of action. It is
metabolised by plasma cholinesterase and muscle paralysis
is prolonged in individuals deficient in this enzyme. It is not
associated with vagolytic activity or ganglionic blockade
although histamine release can occur, particularly with rapid
injection.
Pancuronium bromide, an aminosteroid neuromuscular
blocking drug, has a long duration of action and is often used
in patients receiving long-term mechanical ventilation in
intensive care units. It lacks a histamine-releasing effect, but
vagolytic and sympathomimetic effects can cause
tachycardia and hypertension.
Rocuronium bromide exerts an effect within 2 minutes and
has the most rapid onset of any of the non-depolarising
neuromuscular blocking drugs. It is an aminosteroid
neuromuscular blocking drug with an intermediate duration
of action. It is reported to have minimal cardiovascular
effects; high doses produce mild vagolytic activity.
Vecuronium bromide p. 1409, an aminosteroid
neuromuscular blocking drug, has an intermediate duration
of action. It does not generally produce histamine release
and lacks cardiovascular effects.
Depolarising neuromuscular blocking drugs
Suxamethonium chloride has the most rapid onset of action
of any of the neuromuscular blocking drugs and is ideal if
fast onset and brief duration of action are required, e.g. with
tracheal intubation. Unlike the non-depolarising
neuromuscular blocking drugs, its action cannot be reversed
and recovery is spontaneous; anticholinesterases such as
neostigmine potentiate the neuromuscular block.
Suxamethonium chloride should be given after anaesthetic
induction because paralysis is usually preceded by painful
muscle fasciculations. While tachycardia occurs with single
use, bradycardia may occur with repeated doses in adults and
with the first dose in children. Premedication with atropine
reduces bradycardia as well as the excessive salivation
associated with suxamethonium chloride use.
Prolonged paralysis may occur in dual block, which occurs
with high or repeated doses of suxamethonium chloride and
is caused by the development of a non-depolarising block
following the initial depolarising block. Individuals with
myasthenia gravis are resistant to suxamethonium chloride
but can develop dual block resulting in delayed recovery.
Prolonged paralysis may also occur in those with low or
atypical plasma cholinesterase. Assisted ventilation should
be continued until muscle function is restored.
NEUROMUSCULAR BLOCKING DRUGS ›
DEPOLARISING
PDF pages 1428, 1429
