Vasodilation increases the threshold for bupivacaine-induced convulsions in rats

Status Epilepticus Following Intrathecal Administration of Bupivacaine: A Case Report

Spinal anesthesia is common practice and rarely causes complications. Although extended experience is present, seldom side effects of this technique and the administration of intrathecal local anesthetics and/or opioids can occur. We present a case in which a 76-year old woman undergoing total hip arthroplasty received a low dose of intrathecal bupivacaine and sufentanil. One hour after administration, she developed myoclonic seizures of the lower extremities followed by generalized tonic-clonic seizures and status epilepticus. We conclude that status epilepticus is a rare and possible lethal side effect of intrathecal bupivacaine. Symptoms may be misleading, highlighting the importance of early recognition and adequate management.

Safety Evaluation of EXPAREL (DepoFoam Bupivacaine) Administered by Repeated Subcutaneous Injection in Rabbits and Dogs: Species Comparison

EXPAREL (bupivacaine extended-release liposome injection), DepoFoam bupivacaine, is in development for prolonged postsurgical analgesia. Repeat-dose toxicity studies were conducted in rabbits and dogs to compare the potential local and systemic toxicities of EXPAREL and bupivacaine HCl (Bsol), and the reversibility of any effects. Dogs tolerated much larger doses than rabbits. EXPAREL-related minimal-to-moderate granulomatous inflammation was noted at the injection sites. In recovery animals, the granulomatous inflammation was observed less frequently and was characterized by an increased number of multinucleated giant cells. These effects were considered a normal response to liposomes and nonadverse. Rabbits are more sensitive than dogs. In rabbits, convulsions were noted with EXPAREL and more frequently with Bsol; a NOAEL was not identified. In dogs, EXPAREL was well tolerated (NOAEL > 30 mg/kg/dose). The cumulative exposure of EXPAREL in these studies is well in excess of the proposed maximum single-dose exposure that is intended in humans.

Vasomotor effect after acute intoxication with bupivacaine and levobupivacaine in rats via intraperitoneal route analyzed via digital infrared imaging

BACKGROUND AND OBJECTIVES

The study of the vasomotor effect of local anesthetics (LA) is of paramount importance for the analysis of the occurrence of cardiotoxic and neurotoxic effects, and drug interactions. In order to find a safer drug than racemic bupivacaine, this study aimed to analyze digital infrared imaging of acute vasomotor effect of bupivacaine and levobupivacaine in rats intraperitoneally.

METHOD

We used 30 male Wistar rats distributed into three groups (n=10) and subjected to an intraperitoneal injection of LA. In Group C (control) 1 mL 0.9% saline was injected intraperitoneally. In Group B (bupivacaine), intraperitoneal injection of 0.5% of racemic bupivacaine (S50-R50), dose of 20 mg.kg⁻¹ of body weight. In Group L (levobupivacaine), intraperitoneal injection of levobupivacaine 0.5% enantiomeric excess (S75-R25) in dose of 20 mg.kg⁻¹ of body weight. The procedure was thermographicly continuously filmed from the time of pre-injection until 30 minutes after injection. The results of the recordings were analyzed in graphical form, verifying the maximum temperature of each rat and the average temperature of the system that housed the animal.

RESULTS

The results of graphic analysis showed no difference between Group L and Group C, and the average temperature remained stable throughout the experiment in both groups. In Group B, there was a phenomenon of temperature increase after intraperitoneal injection of bupivacaine.

CONCLUSIONS

The results demonstrated that the vasomotor effect of the acute toxicity of levobupivacaine was similar to Group C with saline, through macroscopic studies by infrared digital filmmaking, and that there were vasomotor changes (vasoconstriction), with bupivacaine intoxication in relation to both Group C and Group L.

Functional adaptation to loading of a single bone is neuronally regulated and involves multiple bones

Regulation of load-induced bone formation is considered a local phenomenon controlled by osteocytes, although it has also been hypothesized that functional adaptation may be neuronally regulated. The aim of this study was to examine bone formation in multiple bones, in response to loading of a single bone, and to determine whether adaptation may be neuronally regulated. Load-induced responses in the left and right ulnas and humeri were determined after loading of the right ulna in male Sprague-Dawley rats (69 +/- 16 days of age). After a single period of loading at -760-, -2000-, or -3750-microepsilon initial peak strain, rats were given calcein to label new bone formation. Bone formation and bone neuropeptide concentrations were determined at 10 days. In one group, temporary neuronal blocking was achieved by perineural anesthesia of the brachial plexus with bupivicaine during loading. We found right ulna loading induces adaptive responses in other bones in both thoracic limbs compared with Sham controls and that neuronal blocking during loading abrogated bone formation in the loaded ulna and other thoracic limb bones. Skeletal adaptation was more evident in distal long bones compared with proximal long bones. We also found that the single period of loading modulated bone neuropeptide concentrations persistently for 10 days. We conclude that functional adaptation to loading of a single bone in young rapidly growing rats is neuronally regulated and involves multiple bones. Persistent changes in bone neuropeptide concentrations after a single loading period suggest that plasticity exists in the innervation of bone.