Drug Monograph
Full clinical overview, indications, dosage references & safety notes.
Overview
Bupivacaine (Sensorcaine®, Marcaine®) is an amide-type local anesthetic widely used in dogs and cats to provide local and regional analgesia for surgical, diagnostic, and therapeutic procedures. Compared with other agents in its class, it has a slower onset of action but a significantly longer duration of analgesia.
Following local administration, onset of analgesia typically occurs within 20 to 30 minutes and may persist for 3 to 5 hours. Because of its prolonged effect, bupivacaine is commonly selected for perioperative pain management, including peripheral nerve blocks and epidural anesthesia. Local analgesia can reduce inhalant anesthetic requirements and improve postoperative comfort.
Mechanism of Action (MOA): Bupivacaine blocks voltage-gated sodium channels on nerve cell membranes, preventing initiation and propagation of action potentials. Sensory fibers (particularly pain fibers) are affected before motor fibers, resulting in sequential loss of pain, temperature, touch, proprioception, and finally motor function. Recovery occurs in the reverse order.
Indications
In dogs and cats, bupivacaine is used to provide local or regional analgesia and anesthesia for a variety of surgical and diagnostic procedures. Its prolonged duration of action makes it particularly useful for perioperative pain management.
- Peripheral nerve blocks: Used for femoral, sciatic, brachial plexus, dental (infraorbital, maxillary, mandibular, mental), and other regional nerve blocks to provide intraoperative and postoperative analgesia.
- Epidural anesthesia/analgesia: Administered via lumbar or caudal epidural injection to provide intraoperative analgesia and reduce opioid and inhalant anesthetic requirements.
- Interpleural analgesia: Used via thoracostomy tube or catheter for thoracic procedures to provide regional analgesia.
- Incisional or wound infiltration: Injected locally at surgical sites to provide postoperative analgesia.
- Intrathecal administration: May be used in selected cases for spinal anesthesia by clinicians experienced with the technique.
- Adjunct combinations: Can be combined with agents such as dexmedetomidine for peripheral nerve blocks or with preservative-free opioids (e.g., morphine, buprenorphine) for epidural analgesia to prolong duration of effect.
Dosage (Reference)
Dog
In dogs, bupivacaine dosing depends on the site of administration, technique used, and desired extent of analgesia. Accurate dose calculation and aspiration prior to injection are essential.
| Clinical use | Route/Technique | Dose | Notes |
|---|---|---|---|
| Peripheral nerve blocks (perineural) | Perineural | • 0.1 mL/kg per site (femoral & sciatic) • 0.1 mL/kg per each of 3 sites (radial, ulnar, musculocutaneous, median) • 0.3 mL/kg (brachial plexus) • 0.25–1 mL total (infraorbital, mental, maxillary, mandibular) |
Select concentration to achieve 1–2 mg/kg total dose within volume guidelines. |
| Epidural analgesia | Epidural | • 1.6 mg/kg (analgesia to L4) • 2.3 mg/kg (analgesia to T11–T13) • 1 mg/kg combined with preservative-free morphine 0.1–0.2 mg/kg |
Limit total volume to 1 mL per 4.5 kg (max 6 mL total). |
| Interpleural analgesia | Thoracostomy tube | 1 mg/kg diluted with saline to total 5–20 mL (depending on size) | Dilution reduces injection discomfort due to acidity. |
• NEVER administer intravenously.
• Always aspirate prior to injection to avoid intravascular administration.
• Accurate volume calculation is critical to prevent systemic toxicity.
• Monitor cardiovascular and respiratory status after administration.
Cat
In cats, bupivacaine dosing follows the same guidelines as in dogs. Careful dose calculation is essential due to increased risk of toxicity with small dosing errors.
| Clinical use | Route/Technique | Dose | Notes |
|---|---|---|---|
| Peripheral nerve blocks | Perineural | Same volume and mg/kg guidelines as dogs | Precise measurement required to prevent overdose. |
| Epidural analgesia | Epidural | Same mg/kg dosing as dogs | Strict adherence to volume limits recommended. |
| Interpleural analgesia | Thoracostomy tube | 1 mg/kg diluted appropriately | Monitor closely for systemic absorption. |
• Accurate dosing is critical to prevent CNS and cardiac toxicity.
• Monitor cardiovascular, respiratory function, and level of consciousness after each injection.
Warnings & Precautions
Bupivacaine is a potent local anesthetic with significant cardiotoxic potential if inadvertently administered systemically. Strict adherence to proper administration technique and patient monitoring is essential in dogs and cats.
- Hypersensitivity: Contraindicated in patients with known hypersensitivity to bupivacaine or other amide-type local anesthetics.
- Intravenous administration: Bupivacaine should never be administered intravenously. Unintentional intravascular injection can result in severe cardiac arrhythmias, cardiac arrest, and death.
- Cardiotoxicity: Bupivacaine is more cardiotoxic than many other local anesthetics; use caution in patients with impaired cardiovascular function.
- Hepatic disease: Use cautiously in patients with hepatic impairment, as metabolism occurs primarily in the liver.
- Epidural precautions: Administer incrementally and aspirate before injection. Do not use preservative-containing formulations for epidural or caudal anesthesia. Avoid use in patients with severe CNS disease.
- Epinephrine-containing formulations: Use cautiously in patients with cardiovascular disease or hyperthyroidism. Avoid use in tissues with compromised circulation (e.g., digits, ears, nose, penis) due to risk of ischemic injury.
- Hyperbaric formulations: Solutions containing dextrose (hyperbaric bupivacaine) are not interchangeable with standard solutions and should not be used for peripheral nerve blocks.
- Malignant hyperthermia susceptibility: Patients predisposed to malignant hyperthermia should receive intensified monitoring.
- Technical expertise required: Clinicians should be knowledgeable in recognition and management of local anesthetic toxicity, and emergency resuscitative equipment must be readily available.
Drug Interactions
Clinically relevant interactions with bupivacaine are primarily related to cardiovascular effects, altered drug clearance, or the addition of epinephrine to local anesthetic solutions. When used in dogs and cats, concurrent medications should be reviewed carefully.
- ACE inhibitors (e.g., benazepril, enalapril): May increase the risk of bradycardia and hypotension when used concurrently.
- Beta-adrenergic antagonists (e.g., atenolol, esmolol, propranolol, sotalol): May increase serum bupivacaine concentrations by reducing clearance, increasing the risk of toxicity.
- Ergot alkaloids: When combined with bupivacaine/epinephrine formulations, may increase the risk of severe and prolonged hypertension.
- Monoamine oxidase inhibitors (MAOIs; e.g., amitraz, selegiline, linezolid): Use with bupivacaine/epinephrine combinations may result in exaggerated hypertensive responses.
- Tricyclic antidepressants (e.g., amitriptyline, clomipramine): May potentiate hypertensive effects when used with epinephrine-containing formulations.
- Vasopressors (e.g., dobutamine, norepinephrine): Concurrent use with epinephrine-containing products may result in excessive hypertension or cardiac stimulation.
Side Effects & Overdose
Side Effects
Bupivacaine is generally well tolerated in dogs and cats when administered correctly. Adverse effects are typically associated with excessive plasma concentrations resulting from overdose, rapid systemic absorption, or inadvertent intravascular or subarachnoid injection.
- Cardiovascular effects: Hypotension, bradycardia, atrioventricular (AV) block, decreased cardiac output, and ventricular arrhythmias may occur with elevated systemic concentrations.
- CNS excitation or depression: Restlessness, tremors, or seizures may occur initially, followed by drowsiness, loss of consciousness, or respiratory depression.
- Gastrointestinal signs: Nausea and vomiting have been reported.
- Chondrolysis (rare): Reported in humans following intra-articular administration; considered unlikely in dogs.
Overdose
Toxicity most commonly results from unintended intravascular administration. Clinical signs may develop rapidly and involve both the cardiovascular and central nervous systems. Immediate recognition and aggressive supportive care are critical.
- Cardiotoxicity: AV block, ventricular arrhythmias, severe hypotension, myocardial depression, and cardiac arrest may occur. Arrhythmias may be refractory to treatment.
- CNS toxicity: Restlessness and tremors progressing to seizures, followed by CNS depression, coma, and respiratory arrest.
- Toxic doses (IV): In dogs, mean convulsive dose ≈4.1 mg/kg and cardiotoxic dose ≈20 mg/kg. In cats, mean convulsive dose ≈3.8 mg/kg and cardiotoxic dose ≈18.4 mg/kg.
- Management: Secure airway and provide oxygen immediately. Control seizures with benzodiazepines or barbiturates. Provide cardiovascular support (IV fluids, vasopressors such as dobutamine or norepinephrine as indicated). Lipid emulsion therapy (20% lipid emulsion at 1.5 mL/kg IV over 30 minutes) may be beneficial. Prolonged resuscitation may be required.
Key Notes
Practical clinical considerations for the use of bupivacaine in dogs and cats:
- Onset vs. duration planning: Because onset is slower (20–30 minutes) but duration is longer (3–5 hours), administer nerve blocks sufficiently in advance of surgical stimulation.
- MAC-sparing effect: Effective regional anesthesia can reduce inhalant anesthetic requirements and improve perioperative hemodynamic stability.
- Lidocaine combination strategy: Mixing lidocaine and bupivacaine does not reliably speed onset and may shorten total duration compared with bupivacaine alone. A practical alternative is to use lidocaine pre-incision and repeat the block with bupivacaine at the end of the procedure.
- Epinephrine addition: When preparing a combination in clinic, the recommended final epinephrine concentration is 5 µg/mL (1:200,000) to reduce systemic absorption and prolong local effect.
- Protein binding: Approximately 95% protein binding may influence distribution and systemic toxicity risk in hypoalbuminemic patients.
- Formulation awareness: Hyperbaric (dextrose-containing) bupivacaine solutions are not interchangeable with standard aqueous formulations.
