Preclinical studies of ropivacaine extended-release from a temperature responsive hydrogel for prolonged relief of pain at the surgical wound.

Postoperative pain is a common form of acute pain that has been treated commonly by local anesthetics through regional nerve blocking. In this study, a series of experiments were conducted using rats to investigate the pharmacokinetic, distribution, and efficacy of a temperature responsive hydrogel-based drug delivery device (PF-72) containing ropivacaine (0.75%) for extended relief of postoperative pain by allowing the prolonged release of ropivacaine. When the ropivacaine was administered using PF-72, its concentration-time curve (AUClast) and peak concentration (Cmax) were 577.0 h*ng/mL and 271.9 ng/mL, respectively. In contrast when the ropivacaine solution was administered using saline solution, its AUClast and Cmax were 982.8 h*ng/mL and 423.6 ng/mL, respectively. In the tissue distribution study, the peak concentration and mean area under the curve of the ropivacaine in injection area (target tissue) were found about 2-fold higher in the case of PF-72 compared with the case of conventional ropivacaine solution. These results clearly demonstrate the capability of PF-72 hydrogel to retain the ropivacaine at the injection site for an extended period. Effective extended (at least 24 h) pain relief of ropivacaine administered using PF-72 was found in the pharmacodynamic study of prolonged analgesic effect. The results of this study indicated that local drug delivery by PF-72 hydrogel formulation may be an effective method to achieve extended relief of pain. Other advantages of ropivacaine administration using PF-72 include reduced systemic side effects and high localization of a drug in target tissues.

Comparison of Postoperative Pain in Laparoscopy-Assisted Distal Gastrectomy and Totally Laparoscopic Distal Gastrectomy by Location of Mini-Laparotomy Site

PURPOSE: We aimed to evaluate the clinical outcomes and determine the degree of postoperative pain associated with the location of mini-laparotomy sites in gastric cancer patients who underwent laparoscopic-assisted distal gastrectomy (LADG) or totally laparoscopic distal gastrectomy (TLDG). METHODS: Between November 2011 and December 2016, 153 patients who underwent surgery for gastric cancer at Kyung Hee University Hospital at Gangdong were reviewed retrospectively. We divided the patients into LADG with epigastric incision, TLDG with umbilical incision (TLDG_U), and TLDG with Pfannenstiel incision (TLDG_P) groups according to the location of incision for anastomosis and specimen removal. There were 37 cases in the LADG group, 85 in the TLDG_U group, and 31 in the TLDG_P group. The clinical characteristics, numeric rating scale (NRS) scores, and postoperative analgesic usage for 7 days of the three groups were compared. RESULTS: There was no statistically significant difference in clinical characteristics including age, sex, body mass index (BMI), TNM staging, and complications among the three groups. There was no significant difference in the amount of total analgesics received; however, the TLDG_P group received more analgesics (5.26±5.053, p=0.412) during the first 7 postoperative days. The TLDG_P group showed higher NRS scores on postoperative days 0, 2, 3, 4, and 5 (p=0.04, 0.001, 0.003, 0.006, and 0.002 respectively). CONCLUSION: Laparoscopic distal gastrectomy can be performed through various incision sites for increasing the safety of mini-laparotomy. However, a Pfannenstiel incision was shown to be more painful than other incisions.