title: A PLGA-PEG-PLGA Thermosensitive Gel Enabling Sustained Delivery of Ropivacaine Hydrochloride for Postoperative Pain Relief.
abstract: Postoperative pain is a complex physiological response to disease and tissue injury. Moderate-to-severe pain typically occurs within 48 h after surgery. Amino amide local anesthetics are widely applied to manage postoperative pain, and they have high efficacy, a low risk for addiction and limited side effects. However, these anesthetics also have short half-lives, often necessitating continuous injection to obtain satisfactory pain relief. In the current work, we used a poly(lactic-co-glycolic acid) (PLGA)-polyethylene glycol (PEG)-PLGA (PLGA-PEG-PLGA) temperature-sensitive gel to deliver a local anesthetic, ropivacaine hydrochloride (RP), to prolong its analgesic effect. We investigated the influence of polymer and drug concentration on gelation temperature and the in vitro drug release rate from the temperature-sensitive gel. RP-loaded PLGA-PEG-PLGA solution is a liquid at room temperature and forms a gel at temperatures slightly lower than body temperature. With regard to the gel's drug release rate, 37.5, 51.3 and 72.6% of RP was released at 12, 24 and 48 h, respectively. This in vitro drug release profile conformed to the Higuchi equation. To assess pain control efficacy when using the gel, we evaluated the mechanical paw withdrawal reflex threshold, thermal pain threshold and incision cumulative pain scores in a rat incisional model. The results showed that the anti-pain effect of a single injection of RP-loaded gel at the incision site lasted for 48 h, which is significantly longer than the effect produced by injection of RP solution alone. The use of RP-loaded thermosensitive gels could provide a promising method for managing postoperative pain.
authors.affiliation: Department of Pharmacy, Wuhan General Hospital of Chinese PLA.
authors.forename: Xudong
authors.initials: X
authors.lastname: Fu
authors.forename: Huilin
authors.initials: H
authors.lastname: Zeng
authors.forename: Jiaping
authors.initials: J
authors.lastname: Guo
authors.forename: Hong
authors.initials: H
authors.lastname: Liu
authors.forename: Zhen
authors.initials: Z
authors.lastname: Shi
authors.forename: Huhai
authors.initials: H
authors.lastname: Chen
authors.forename: Dezong
authors.initials: D
authors.lastname: Li
authors.forename: Xiangyang
authors.initials: X
authors.lastname: Xie
authors.forename: Changchun
authors.initials: C
authors.lastname: Kuang
mesh_terms: D000577:Amides / Q000008:administration & dosage* / Q000737:chemistry / Q000627:therapeutic use*; D000779:Anesthetics, Local / Q000008:administration & dosage* / Q000737:chemistry / Q000627:therapeutic use*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D016503:Drug Delivery Systems; D010147:Pain Measurement; D010149:Postoperative Pain / Q000188:drug therapy* / Q000473:pathology; D011092:Polyethylene Glycols / Q000008:administration & dosage / Q000737:chemistry*; D011098:Polyglactin 910 / Q000008:administration & dosage / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012212:Rheology; D000077212:Ropivacaine; D013696:Temperature; D013997:Time Factors
chemical_list: D000577:Amides; D000779:Anesthetics, Local; C528571:poly(lactic-co-glycolic acid)-polyethylene glycol-poly(lactic-co-glycolic acid); D011098:Polyglactin 910; D011092:Polyethylene Glycols; D000077212:Ropivacaine