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Bupivacaine a rarely local anesthetic agent

Group: local anaesthetic agent

Injection (hydrochloride): 2.5 mg/ml (0.25%) or 5 mg/ml (0.5%) in 10-ml ampoule; 5 mg/ml (0.5%) in 1.8-ml cartridge for dental anaesthesia; 7.5 mg/ml (0.75%) with glucose 82.5 mg/ml (8.25%) in 4-ml ampoule

General information


Bupivacaine is a long-acting local anaesthetic. Addition of epinephrine is thus rarely required. It blocks initiation and transmission of nerve impulses at the site of application by stabilizing the neuronal membrane. The compound is ultimately metabolized in the liver. Depending upon the site of injection and the concentration used, anaesthesia usually lasts 2-4 hours.


Clinical information

gafacom image for Bupivacaine

Uses

• Infiltration anaesthesia.
• Peripheral and sympathetic nerve block.
• Dental anaesthesia.
• Spinal anaesthesia.
• Epidural and caudal anaesthesia (these techniques produce prolonged regional anaesthesia, and should be attempted only by experienced specialist anaesthetists).

Bupivacaine is unsuitable for intravenous regional anaesthesia or for topical application.

Mechanism of action




Bupivacaine binds to the intracellular portion of voltage-gated sodium channels and blocks sodium influx into nerve cells, which prevents depolarization. Without depolarization, no initiation or conduction of a pain signal can occur.

Dosage and administration

The aim is to administer the smallest effective dose. This varies with the procedure adopted, the degree of anaesthesia required, the rate of absorption from the injection site and the size and responsive-ness of the patient. Higher initial blood levels are attained with more concentrated solutions.

The maximum cumulative safe dose for adults and children of a 0.25% solution of bupivacaine is 1.5 mg/kg. The table provides a general guide to dosage in adults. Smaller dosages should be administered to debilitated, elderly, epileptic and acutely ill patients.

Bupivacaine is generally not recommended for children aged less than 12 years since there is insufficient information on the effects of its use in this age group.

Solutions containing preservatives should not be used for spinal, epidural or caudal anaesthesia.

Spinal anaesthesia


Spinal anaesthesia should be attempted only by a person fully trained in the technique and competent to treat possible complications. A “heavy” solution (0.75% bupivacaine in 8.25% glucose) will provide the muscular relaxation required for abdominal surgery. Full aseptic technique must be employed for the injection and the patient must be appropriately tilted to ensure safety and the required level of analgesia.

Spinal anaesthesia always causes hypotension as a result of sympathetic blockade. It should never be used in patients with any condition resulting in hypovolaemia. 

The hypotensive response may largely be averted by preliminary intravenous infusion of 500-1000 ml of physiological saline (9 mg/ml) but blood pressure should always be measured every 2 minutes for at least 10 minutes. Postoperative headache can be prevented by instructing the patient to remain supine for 24 hours.

Obstetric practice


Lumbar epidural block has largely replaced caudal epidural block for relief of pain in labour. It requires less local anaesthetic, carries less risk of infection and is readily extended should caesarean section become necessary. 

However, because of the risk to both the mother and the fetus, it should be attempted only by an experienced specialist anaesthetist. Concentrations of bupivacaine greater than 0.5% are contraindicated for this purpose in view of reports of cardiac arrest and maternal death. 

Maternal blood pressure, fetal heart rate and uterine contractions should be monitored throughout the procedure. Paracervical block is no longer recommended during labour because it results in very high levels of the drug in fetal blood.

Contraindications


• Known or suspected hypersensitivity to bupivacaine.
• Skin infection adjacent to the intended site of injection, concomitant anticoagulant therapy or an abnormal bleeding tendency.
• Severe anaemia or heart disease.
• Spinal and epidural anaesthetics should never be administered to dehydrated or hypovolaemic patients. 

Use in pregnancy


Safe use in early pregnancy has not been established. However, there is no clinical evidence to suggest that exposure of the mother to bupivacaine is harmful to the fetus.

Adverse effects

These may result from excessive dosage, inadvertent intravascular injection, or injection into highly vascular tissues. Initial signs of light-headedness, dizziness, blurred vision, restlessness, tremors and, occasionally, convulsions are rapidly followed by drowsiness, unconsciousness and respiratory failure. Myocardial depression and hypotension can result in hypoxia, acidosis, heart block and cardiac arrest.

Hypersensitivity and allergic reactions may also occur. Epidural anaesthesia is occasionally complicated by urinary retention, faecal incontinence, headache, backache or loss of perineal sensation. Transient paraesthesiae and paraplegia are very rare complications.

Drug interactions

Co-administration of oxytocic drugs post-partum may cause severe and prolonged hypertension. The use of bupivacaine preparations containing epinephrine during or following the administration of halothane or trichloroethylene creates a risk of cardiac dysrhythmias.

Overdosage


Overdosage or accidental intravascular injection is characterized by the systemic effects described above. Treatment is symptomatic. There is no specific anti dote. A clear airway should be maintained and ventilation assisted as required. Convulsions may be controlled by diazepam or thiopental.
Bupivacaine a rarely local anesthetic agent Bupivacaine a rarely local anesthetic agent Reviewed by gafacom on July 17, 2019 Rating: 5

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