Abstract

We have previously developed ammonium sulphate gradient loaded liposomes to encapsulate dibucaine. Thus, the purpose of this study was to evaluate the pre-clinical safety and effectiveness of this novel ionic liposomal formulation of dibucaine (DBC), as described in previous work. Effectiveness was evaluated in vivo on Wistar rats (n = 8) that received plain DBC or liposomal DBC (DBC_LUV). Control empty liposomes (without DBC) or saline were also used as control. Sciatic nerve block was performed using the formulations or controls (0.4 mL). A hindpaw incision-based postoperative pain model was used to evaluate mechanical hypersensitivity with von Frey filaments. To verify antiinflamatory activity protein levels of TNF-α, IL-1β, substance P and CGRP were measured by ELISA in the hindpaw tissue after 1 and 6 hours of the incision. To corroborate drug safety, sciatic nerve Schwann cell cultures were treated with the aforementioned formulations and assessed for cell viability (MTT assay) and death (flow cytometry assay). Histopathology of the tissues surrounding the sciatic nerve region was also assessed 2 and 7 days after treatment. All animals presented post incisional hypersensitivity and DBC_LUV showed longer analgesic effect (p < 0.001). DBC_LUV reduced TNF-α and CGRP levels (p < 0.05). Histopathological evaluation showed greater inflammatory reaction after the administration of control liposomes when compared to DBC (p < 0.05). There was no difference in Schwann cell viability and death between plain and encapsulated DBC. DBC_LUV was safe and enhanced anaesthesia duration due to slow release of dibucaine from ammonium sulphate gradient loaded liposomes.

摘要

我们以前开发了硫酸铵梯度加载脂质体来封装地布卡因。因此，本研究的目的是评估这种新型地布卡因 (DBC) 离子脂质体制剂的临床前安全性和有效性，如先前工作所述。对接受普通 DBC 或脂质体 DBC (DBC _LUV ) 的 Wistar 大鼠 (n = 8)进行体内有效性评估）。对照空脂质体（不含 DBC）或盐水也用作对照。使用制剂或对照(0.4mL)进行坐骨神经阻滞。基于后爪切口的术后疼痛模型用于评估von Frey细丝的机械超敏反应。为了验证TNF-α、IL-1β、P物质和CGRP的抗炎活性蛋白水平，在切口1小时和6小时后通过ELISA在后爪组织中测量。为了证实药物安全性，用上述制剂处理坐骨神经施万细胞培养物并评估细胞活力（MTT测定）和死亡（流式细胞术测定）。在治疗后 2 天和 7 天还评估了坐骨神经区域周围组织的组织病理学。所有动物均出现切口后超敏反应和 DBC _LUV显示出更长的镇痛作用（p  < 0.001）。DBC _LUV降低了 TNF-α 和 CGRP 水平 ( p  < 0.05)。组织病理学评估显示，与 DBC 相比，给予对照脂质体后炎症反应更大（p  < 0.05）。普通 DBC 和封装 DBC 之间的雪旺氏细胞活力和死亡没有差异。DBC _LUV是安全的，并且由于二丁卡因从加载硫酸铵梯度的脂质体中缓慢释放而延长了麻醉持续时间。