Postoperative Pain Control & the Extended-Release Local Anesthetic

Sponsored by Aratana

Local anesthetics are excellent analgesics, considered by the 2015 AAHA pain guidelines as "the only class of drug that renders complete analgesia."¹ However, their duration of action has traditionally limited their utility to the immediate perioperative period.

In 2016, the FDA approved the use of an extended-release bupivacaine as a single-dose infiltration into the surgical site to provide local postoperative analgesia for cranial cruciate ligament (CCL) surgery in dogs and later expanded the label to include its use as a peripheral nerve block to provide regional postoperative analgesia following onychectomy in cats.^2-4 The introduction of this innovative, extended-release bupivacaine is an exciting advancement in local anesthetic technology, which extends its benefits up to 72 hours postoperatively.

Lidocaine and Bupivacaine: The Traditional Options

Local anesthetics provide analgesia by reversibly blocking sodium-gated channels in neurons, preventing their depolarization and thus inhibiting transmission of action potentials.⁵ Lidocaine and bupivacaine are the most common local anesthetics used in veterinary practice and are both amide local anesthetics metabolized by the liver.⁵ Lidocaine has a quick onset of action, but a short duration of action.⁵ Bupivacaine has a slow onset of action; however, because almost 95% of it is protein bound, its duration of action is up to 8 hours.^5,6 The waning of these local anesthetics postoperatively can lead to heavy reliance on systemic analgesics, such as NSAIDs and opioids, potentially allowing for breakthrough pain.

Liposomal Bupivacaine: The Extended-Release Approach

Extended-release bupivacaine utilizes liposomal technology to slowly release bupivacaine into the tissues.^5-7 These microscopic liposomes consist of many vesicles tightly packed in a nonconcentric, honeycomb-like manner, and their lipid bilayer is composed of biodegradable phospholipids, cholesterol, and triglycerides.^5-7 The unaltered, aqueous bupivacaine is encapsulated in these vesicles.^5-7 Over time, the lipid bilayer of the vesicles degrades and reorganizes, releasing the aqueous bupivacaine into the tissues, vesicle by vesicle.^5-7 This gradual degradation of the vesicles allows for a slow release of the bupivacaine into the tissue.

The stability of multivesicular liposomes produces a reliable safety and efficacy profile. Multiple safety studies have been conducted in dogs during the development of this drug for humans, and they have established the safety of liposomal bupivacaine.^5,7 Additionally, recent studies demonstrated liposomal bupivacaine's efficacy in dogs and cats. Liposomal bupivacaine was shown to control pain 24 hours after surgery in 68.8% of dogs post CCL repair and 75.2% of cats post onychectomy in 2 separate multicenter, placebo-controlled field studies on client-owned animals.^8,9 Moreover, the analgesic benefits persisted for 72 hours after surgery for 61.6% of dogs and 68.4% of cats.^8,9

Conclusion

Liposomal bupivacaine provides veterinarians with an effective method to alleviate pain for up to 72 hours after CCL repair and onychectomy surgery, potentially reducing the amount of systemic medications necessary to keep patients comfortable. Especially during the current opioid shortage, it is particularly important for veterinarians to keep in mind these alternative approaches to postsurgical pain control.

DOG INDICATION: NOCITA® (bupivacaine liposome injectable suspension) is indicated for single-dose infiltration into the surgical site to provide local postoperative analgesia for cranial cruciate ligament surgery in dogs.

CAT INDICATION: NOCITA® (bupivacaine liposome injectable suspension) is indicated for use as a peripheral nerve block to provide regional postoperative analgesia following onychectomy in cats.

Important Safety Information: NOCITA® (bupivacaine liposome injectable suspension) is for use in dogs and cats only. Do not use in dogs or cats younger than 5 months of age, that are pregnant, lactating or intended for breeding. Do not administer by intravenous or intra‐arterial injection. Adverse reactions in dogs may include discharge from incision, incisional inflammation and vomiting. Adverse reactions in cats may include elevated body temperature, infection or chewing/licking at the surgical site. Avoid concurrent use with bupivacaine HCl, lidocaine or other amide local anesthetics. Please see the full Prescribing Information for more detail.