Bupivacaine
Bupivacaine is a long-acting amide local anesthetic used to interrupt sensation at a surgical site or along a regional nerve distribution. It supports local infiltration, peripheral nerve blocks and selected epidural techniques, reducing nociceptive input and the need for systemic analgesics within a multimodal plan. It generally has a slower onset and longer action than lidocaine.
Conventional bupivacaine hydrochloride and liposomal bupivacaine are distinct formulations. Slow release from liposomes can prolong local exposure, but dosing, permitted sites and expected duration cannot be transferred indiscriminately between products.
Group
Local anesthetic
Mechanism of Action
The uncharged fraction of bupivacaine crosses the nerve-cell membrane. Within the cell, drug interacts with voltage-gated sodium channels and limits the sodium influx required to initiate and propagate action potentials. Blocking conduction prevents sensory signals from reaching the central nervous system from the anesthetized region.
The extent of block depends on concentration, dose, tissue environment and the nerve structures exposed. Sensory, motor and autonomic fibers can all be affected, so the result may include muscle weakness or sympathetic blockade as well as analgesia. Regional analgesia therefore differs from simply sedating the animal.
In liposomal products, gradual release from lipid vesicles maintains drug near the administration site for longer. The sodium-channel target remains the same. Excess systemic exposure can also block cardiac sodium channels and affect central neurons, explaining potentially severe cardiovascular and neurologic toxicity.
Dose Rates
Dogs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Epidural anesthesia | Reference only | EPIDURAL | Conventional bupivacaine 1–1.5 mg/kg epidurally. Maintain approximately 0.2 mL/kg total volume and no more than 6 mL in large dogs; the volume cap is formulation- and procedure-dependent. |
Cats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Epidural anesthesia | Reference only | EPIDURAL | Conventional bupivacaine 1–1.5 mg/kg epidurally. Maintain approximately 0.2 mL/kg total volume and no more than 6 mL in large dogs; the volume cap is formulation- and procedure-dependent. |
Indications
- Local infiltration to provide anesthesia and postoperative analgesia at an appropriate surgical or wound site.
- Peripheral nerve blockade for regional analgesia, as part of a technique and dose appropriate to the nerves and tissues involved.
- Selected epidural anesthesia or analgesia, using a formulation suitable for that route and accounting for the extent of motor and autonomic effects.
- Prolonged postoperative local analgesia with a supported liposomal preparation for the product- and procedure-specific uses that have been evaluated.
- Bupivacaine provides regional interruption of nociceptive transmission; it does not provide general unconsciousness or treat an underlying painful disease outside the blocked area.
Contraindications
- Never administer local anesthetic preparations intravenously.
- Do not inject liposomal products into joints.
- Epinephrine-containing products require separate patient assessment.
- Hypersensitivity to amide local anesthetics; avoid intravascular delivery and incompatible local-anesthetic mixtures.
Interactions
- Avoid incompatible acidic or alkaline mixtures; alkalinized conventional solutions must be used promptly.
Adverse effects
- Arrhythmias and bradycardia
- Tremors, twitching and seizures
- Respiratory paralysis after excessive epidural dosing
- Local tissue irritation
Toxicity
Systemic toxicity may cause severe cardiac arrhythmias or seizures. The reported feline toxic dose for conventional bupivacaine is 5 mg/kg; this must not be applied to liposomal products.
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Bupivacaine 2.5 mg/mL injection Conventional hydrochloride solution. Local and peripheral uses are described under Monitoring and Administration. | Injection | 2.5 mg / mL | EPIDURAL |
| Bupivacaine 5 mg/mL injection Conventional hydrochloride solution. Local and peripheral uses are described under Monitoring and Administration. | Injection | 5 mg / mL | EPIDURAL |
| Bupivacaine 7.5 mg/mL injection Conventional hydrochloride solution. Local and peripheral uses are described under Monitoring and Administration. | Injection | 7.5 mg / mL | EPIDURAL |
Monitoring and Administration
Have respiratory support available for epidural procedures. Conventional epidural volume is approximately 0.2 mL/kg and should not exceed 6 mL in large dogs.
A conventional peripheral block commonly uses 0.2 mL/kg of 0.5% solution (1 mg/kg).
Liposomal bupivacaine 13.3 mg/mL: canine tissue infiltration uses 5.3 mg/kg (0.4 mL/kg) once. Feline onychectomy uses 5.3 mg/kg per forelimb, total 10.6 mg/kg per cat, by four-point nerve block; individual nerve-site volumes are 0.02–0.16 mL/kg according to the procedure. Local infiltration and peripheral blocks are outside the calculator route set.
The human multivesicular formulation has also been described at 100–200 mg per site with effect up to 96 hours. Do not substitute this for veterinary liposomal regimens.
For veterinary liposomal infiltration, use a 25-gauge needle and inject slowly. Saline or lactated Ringer’s may be added up to an equal volume; do not use water or incompatible solutions.
Do not use discolored conventional solutions. Liposomal vials are refrigerated and must not be frozen. After drawing up, discard after 4 hours. Unopened liposomal vials may remain at room temperature for up to 30 days and must not be re-refrigerated.
Liposomal bupivacaine is procedure-specific and must not be interchanged with conventional bupivacaine hydrochloride. For the veterinary liposome product, do not administer concurrently with conventional bupivacaine, lidocaine or other amide local anesthetics; a safe separation interval has not been established. Avoid intravascular injection. Use incremental injection with repeated aspiration to reduce inadvertent vascular delivery.