Preclinical Evaluation of Ropivacaine in 2 Liposomal Modified Systems

Abstract

(Anesth Analg. 2019;129(2):387–396) Postoperative pain management is a challenge, with only 1 in 4 surgical patients in the United States reporting adequate pain relief. This can lead to unwanted consequences, such as excessive analgesic use. The authors of this study recently developed new liposomal delivery models for ropivacaine (RVC), and they sought to assess these formulations for postoperative pain control in animal models.

Ropivacaine-Loaded Poloxamer Binary Hydrogels for Prolonged Regional Anesthesia: Structural Aspects, Biocompatibility, and Pharmacological Evaluation

“…Sciatic nerve blockade model was used to assess the regional local anesthetic effects. Animals were treated by formulation injection (0.4 mL) into the greater trochanter region of the right posterior limb, in the region close to the sciatic nerve [30]. RVC concentration was 0.5% for all formulations.…”

“…After motor and sensory blockade evaluation, animals were euthanized under general anesthesia (urethane 1 g/kg and α-chloralose 50 mg/kg) after 2 or 7 days, to evaluate the tissue morphological damage (n = 3/each evaluation time). The sciatic nerve adjacent tissue was excised, and cross-sections (5 μm thick, 40 μm deep) were prepared by staining with hematoxylin and eosin and qualitatively analyzed by a blinded examinator using the following score system to determine local inflammation and leukocyte infiltration: (1) <25% total area without infiltrate, injury, or necrosis (mild inflammation), (2) 25%-50% area with inflammatory infiltrate, injury, or necrosis (moderate inflammation), and (3) >50% area with injury and displays necrosis areas (severe inflammation) [30].…”

Comparative analysis of two laser wavelengths in the stimulation of acupuncture points for analgesic effects in an animal model

“…The threshold was measured in triplicate format at 10-minute intervals, and the means of the forces providing the paw withdrawal reflex was considered as the baseline sensitivity [40,41].…”

“…The right hind paw underwent a 1 cm incision made with an 11-blade scalpel on the plantar surface, starting at 0.5 cm from the heel of the paw. The incision was closed with a 5-0 nylon suture [41,42]. After the surgery, the withdrawal response was used to determine the painful sensitivity of the right and left hind paws.…”

“…Painful sensitivity was measured in the triplicate format with 10-minute intervals between measurements. The mean of the forces that caused the paw withdrawal reflex was considered the painful sensitivity [40,41].…”