Pharmacokinetics of bupivacaine after intraperitoneal administration to cats undergoing ovariohysterectomy

Abstract

OBJECTIVE To evaluate pharmacokinetics of bupivacaine after IP administration to cats undergoing ovariohysterectomy. ANIMALS 8 healthy cats. PROCEDURES Anesthesia was induced with propofol and maintained with isoflurane. Buprenorphine (0.02 mg/kg, IV) and meloxicam (0.2 mg/kg, SC) were administered. A 20-gauge catheter was inserted into a jugular vein for blood sample collection. A ventral midline incision was made, and a solution of 0.5% bupivacaine (2 mg/kg) diluted with an equal volume of saline (0.9% NaCl) solution (final concentration, 0.25% bupivacaine) was injected into the peritoneal space over the right and left ovarian pedicles and caudal aspect of the uterus before ovariohysterectomy. Cats were monitored for signs of bupivacaine toxicosis. Venous blood samples (2 mL) were collected before (time 0) and 2, 5, 10, 15, 20, 30, 60, 120, and 240 minutes after bupivacaine administration. Plasma bupivacaine concentrations were determined with a liquid chromatography-tandem mass spectrometry method. Pharmacokinetic parameters were determined by data plotting followed by analysis with a noncompartmental model. RESULTS No signs of bupivacaine toxicosis were observed. Maximum bupivacaine plasma concentration was 1,030 ± 497.5 ng/mL at a mean ± SD value of 30 ± 24 minutes after administration. Mean elimination half-life was 4.79 ± 2.7 hours. Mean clearance indexed by bioavailability and volume of distribution indexed by bioavailability were 0.35 ± 0.18 L•h/kg and 2.10 ± 0.84 L/kg, respectively. CONCLUSIONS AND CLINICAL RELEVANCE Intraperitoneal administration of bupivacaine resulted in concentrations that did not cause observable toxicosis. Studies to investigate analgesic effects for this technique in cats are warranted.

A retrospective study of anesthesia for subcutaneous ureteral bypass placement in cats: 27 cases

“…A trend towards the decrease in hospitalization time was observed with the use of the IP technique which was not significantly, but could be clinically relevant to an individual cat while reducing stress and costs with hospitalization. IP administration of bupivacaine has shown to be safe and to provide postoperative analgesia in cats undergoing OVH [3, 4], and it has been made part of the standard analgesic protocol for SUB placement at the authors’ institution. In human medicine, many studies have reported the benefits of local anesthetics to reduce risk factors associated with morbidity or to accelerate recovery [9].…”

Intraperitoneal and incisional analgesia in small animals: simple, cost‐effective techniques

“…There is no evidence that these techniques should replace other analgesics such as nonsteroidal anti‐inflammatory drugs (NSAIDs) but, rather, should be used in addition. IP and incisional analgesia should be used as part of a multimodal analgesic plan (Benito et al . ). For example, the combination of an opioid, NSAID and IP and incisional anaesthesia provides adequate postoperative analgesia in cats undergoing ovariohysterectomy (Benito et al .…”

“…For example, the combination of an opioid, NSAID and IP and incisional anaesthesia provides adequate postoperative analgesia in cats undergoing ovariohysterectomy (Benito et al . ). Total doses of bupivacaine 0.5% should not exceed 4 mg/kg in dogs and 2 mg/kg in cats (Benito et al . , , ).…”

“…). Total doses of bupivacaine 0.5% should not exceed 4 mg/kg in dogs and 2 mg/kg in cats (Benito et al . , , ). Based on the experience of the authors, if both techniques are used, one‐fourth of the total dose is administered for incisional anaesthesia whereas the remaining volume is used for IP analgesia. In cats, bupivacaine 0.5% can be diluted in equal parts with saline to increase the volume of IP injection.…”

“…, Benito et al . , , ), this technique should be readily applied in sterilisation programs, especially in countries with limited drug availability. They should always be performed under strict aseptic conditions and general anaesthesia. There is no evidence that these techniques should replace other analgesics such as nonsteroidal anti‐inflammatory drugs (NSAIDs) but, rather, should be used in addition. IP and incisional analgesia should be used as part of a multimodal analgesic plan (Benito et al .…”