Bupivacaine
Hydrochloride
5mg/ml
Solution for Spinal Injection
Drug
Category: Local Anesthetic
Brand
Name: Sensorcaine 0.5% Heavy
Clinical
Particulars
Therapeutic
Indications:
Spinal
anesthesia for surgery, e.g. urological surgery and surgery on the
lower limbs lasting 2-3 hours, abdominal surgery lasting 45-60
minutes.
Dosage
and method of administrations:
Bupivacaine
hydrochloride Spinal Heavy should only be used by clinicians with
experience of regional anesthesia or under their supervision. The
lowest possible dose for adequate anesthesia should be used.
The
doses given below are guides for adults and the dosage should be
adjusted to the individual patients.
The
dose should be reduced in elderly patients and patients in late
stages of pregnancy.
Indication
|
Dose mL
|
Dose mg
|
Time to onset of
effect in minutes (approx.)
|
Duration of
effect in hours (approx.)
|
Urological
surgery
Surgery on lower limbs, including hip surgery Abdominal surgery (including cesarean section) |
1.5-3 ml
2-4 ml 2-4 ml |
7.5-15 mg
10-20 mg 10-20 mg |
5-8 min
5-8 min 5-8 min |
2-3 hours
2-3 hours 45-60 min |
The
recommended injection site is the L3-L4
intervertebral space. There is currently no experience of doses
higher than 20 mg. A spinal injection is given only after the
subarachnoid space has been clearly identified by means of lumbar
puncture (clear cerebrospinal fluid runs out via the spinal needle or
is seen on aspiration). In the event of unsuccessful anesthesia, a
new attempt to administer the drug should only be made by injecting
at a different level and with a smaller volume. One cause of lack of
effect may be poor intrathecal distribution of the drug, and this can
be helped by altering the patient's position.
Contraindications:
Hypersensitivity
to local anesthetics of the amide type or to other components of the
product. Diseases of the central nervous system (e.g. meningitis,
poliomelitis, intracranial hemorrhage). Local pyogenic infection at
or adjacent to the injection site. Spinal stenosis and active disease
(e.g. spondylitis, tumor) or trauma (e.g. fracture of the spine).
Septicemia, pernicious anemia with subacute degeneration of the
spinal cord. Spinal anesthesia should not be given to patients in
shock. Nor should spinal anesthesia be given to patients with
coagulation disorders or to patients receiving ongoing
anticoagulation treatment.
Special
warning and precaution for use:
One
should be aware that spinal anesthesia can sometimes lead to major
blocks, with paralysis of intercostal muscles and the diaphragm,
especially in pregnant women.
Caution
should be exercised in patients with degree II or III-AV block since
local anesthetics can lower the conduction capacity of the
myocardium. Elderly patients and patients with severe hepatic
disease, severely impaired renal function or in generally reduced
general condition also require special attention.
Patients
treated with class III anti-arrhythmic drugs (e.g. amiodarone) should
be closely observed and ECG monitoring should be considered, since
the cardiac effects of bupivacaine and class III anti-arrhythmic
drugs can be addictive.
Like
all local anesthetic drugs, bupivacaine can cause acute central
nervous and cardiovascular toxic effects in cases of use leading to
high concentrations in the blood. This applies particularly after
inadvertent intravascular administration.
Ventricular
arrhythmia, ventricular fibrillation, sudden cardiovascular collapse
and death have been reported in association with high systemic
concentrations of bupivacaine. However, with doses normally used for
spinal anesthesia high systemic concentrations are uncommon.
An
uncommon, but dangerous, side effect in spinal anesthesia is
extensive or total spinal blockade, which results in cardiovascular
depression and respiratory depression. The cardiovascular depression
is caused by extensive sympathetic blockade, which can result in
hypotension and bradycardia, or even cardiac arrest. Respiratory
depression can be caused by blockade of the innervation of the
respiratory muscles, including the diaphragm. There is an increased
risk of extensive or total spinal blockade in elderly patients and
patients in late stages of pregnancy. The dose should therefore be
reduced for these patients.
Spinal
anesthesia can lead to a fall in blood pressure and bradycardia. The
risk can be reduced by means of intravenous administration of
crystalloid or colloid solution. A fall in blood pressure should be
treated immediately, for example with ephedrine 5-10mg intravenously,
repeated as required.
In
rare cases spinal anesthesia can cause neurological damage, resulting
in paresthesia, anesthesia, motor weakness and paralysis.
Neurological disorders, such as multiple sclerosis, hemiplegia,
paraplegia and neuromuscular disturbances are not thought to be
adversely affected by spinal anesthesia, but caution should be
exercised.
Interactions
with other medical products and other forms of interactions:
Bupivacaine
should be use with caution with other local anesthesia or drugs that
are structurally similar to local anesthetics, i.e. class IB
anti-arrhythmic drugs, as the toxic effects are additive.
No
specific interaction studies with local anesthesia and class III
anti-arrhythmic drugs (e.g. amiodarone) have been carried out, but
caution is recommended (see Special warning and special precautions
for use).
Pregnancy
and Lactation:
Pregnancy
No
known risks for the fetus from use during pregnancy. However, note
that the dose should be reduced for patients in late stages of
pregnancy (see Special warning and special precautions for use).
Lactation
Bupivacaine
passes into breast milk, but the risk of this affecting the child
appears unlikely with therapeutic doses.
Effects
on ability to drive and use machines:
Depending
on the dose and method of administration, bupivacaine can have a
transient effect on movement and coordination.
Undesirable
effects:
Undesirable
effects caused by the product itself can be difficult to distinguish
form the physiological effects of the nerve block (e.g.
fall in blood pressure, bradycardia, temporary urinary retention),
events caused directly by the needle puncture (e.g. spinal hematoma)
or caused indirectly by the needle puncture (e.g. meningitis,
epidural abscess) or events associated with leakage of cerebrospinal
fluid ( e.g. post lumbar puncture headache).
Very
common
(>1/10) |
General:
Nausea
Circ.: Hypotension, bradycardia |
Common
(>1/100) |
CNS: Post lumbar
puncture headache
GI: Vomiting Genitourinary: Urinary retention, urinary incontinence |
Uncommon
(1/100-1/1000) |
CNS:
Paresthesia, paresia, dysesthesia
Musculoskel.: Muscle weakness, back pain |
Rare
(<1/1000) |
Circ.: Cardiac
arrest
General: Allergic reactions, anaphylactic shock CNS: Accidental total spinal blockade, paraplegia, paralysis, neurophathy, arachnoiditis Airways: Respiratory depression |
Overdose:
Bupivacaine
can cause acute toxic effects of a central nervous and cardiovascular
nature if it is given in high doses, especially if it is administered
intravascularly. However, the dose used in spinal anesthesia is low
(≤ 20% of the dose used for epidural anesthesia) and thus the risk
of overdosage is unlikely. In cases of concomitantly administration
with other local anesthetics, however, systemic toxic effects may
occur, ass the toxic effects are additive.
Treatment
of complications
In
cases of total spinal blockade adequate ventilation must be ensured
(patent airways, oxygen, intubation and controlled ventialtion if
necessary). If there is a fall in blood pressure a vasopressor
(preferably with an inotropic effect) should be given, e.g. ephedrine
5-10mg intravenously.
If
signs of acute systemic toxicity occur the administration of local
anesthesia must be stopped immediately. Treatment must be given to
maintain good ventilation, oxygenation and circulation. Oxygen must
always be given, and assisted ventilation if necessary. If
convulsions do not cease spontaneously within 15-20 seconds,
theopentone sodium 1-3 mg/kg should be given intravenously to
facilitate ventilation or diazepam 0.1 mg/kg intravenously ( acts
rather more slowly). Prolonged seizures jeopardize the patient's
respiration and oxygenation. Injection of muscle relaxants (e.g.
suxamethonium 1mg/kg) creates more favourable conditions for
ventilation and oxygenation of the patient, but requires experience
of tracheal intubation and controlled ventilation. In cases of a fall
in blood pressure/bradycardia, a vasopressor should be given (e.g.
ephedrine 5-10 mg intravenously, which may be repeated after 2-3
minutes). In the event of circulatory arrest, cardiopulmonary
resuscitation should be instituted immediately. It is important to
maintain good oxygenation, respiration and circulation, and to treat
acidosis.
Children
must be given doses in proportion to their age and body weight for
treatment of systemic toxicity.
Pharmacological
Properties
Pharmacodynamic
Properties
Bupivacaine
hydrochloride spinal heavy contains bupivacaine, which is a
long-acting local anesthetic of the amide type. Bupivacaine
reversibly blocks impulse conduction in the nerves by inhibiting the
transport of sodium ions through the nerve membrane. Similar effects
can also be seen on excitatory membranes in the brain and myocardium.
Bupivacaine
hydrochloride spinal heavy is intended for hyperbaric spinal
anesthesia. The relative density of the solution for injection is
1.026 at 20oC (equivalent to 1.021 at 37oC) and
the initial distribution into the subarachnoid space is markedly
influenced by gravity.
For
administration into the spine, a small dose is given, which gives a
relatively low concentration and short duration of effects.
Bupivacaine hydrochloride spinal (without glucose) produces a less
predictable block, but with a longer duration of effects than
bupivacaine hydrochloride spinal heavy (with glucose).
Pharmacokinetic
Properties:
Bupivacaine
is very liposoluble with an oil/water distribution coefficient of
27.5.
Bupivacaine
displays complete and bi-phasic absorption from the subarachnoid
space, with half-lives for the two phases of approx. 50 and approx.
400 minutes, with large variations. The slow absorption phase is the
rate-determining factor in the elimination of bupivacaine, which
explains why the apparent half-life is longer than after intravenous
administration.
Absorption
form the subarachnoid space is relatively slow, which, in combination
with the low dose required a spinal anesthesia, gives relatively low
plasma concentration (approx. 0.4 mg/mL per 100 mg injected).
After
intravenous administration, total plasma clearances is approx. 0.58
L/min, the volume of distribution in steady state is approx. 73 L,
the elimination half-life is 2.7 hours, and the hepatic extraction
ration is approx. 0.40. Bupivacaine is metabolized almost completely
in the liver, predominantly through aromatic hydroxylation to
4-hydorxybupivacaine and N-dealkylation to PPX, both of which are
mediated by cytochrome P450 3A4. Clearance is thus depended on
hepatic perfusion and the activity of the metabolizing enzyme.
Bupivacaine
crosses the placenta and the concentration of free bupivacaine is the
same in the the mother and the fetus. However, the total plasma
concentration is lower in the fetus, which has a lower degree of
protein binding.
Pharmaceutical
Particulars
Incompatibilities:
Additions
to spinal solutions are not recommended.
Shelf-Life:
Please
refer to the expiration date.
The
solution must be used as soon as possible after the container has
been opened.
Storage:
Store
at a temperature not exceeding above 25oC. Do not freeze.