AIM:This study aims to investigate the sustained and stable drug release profile of the injectable hydrogel lidocaine(LDC)/betamethasone sodium phosphate hydrogel(BetP-Gel)and its effect on analgesic duration in a mouse model of acute incisional pain.METHODS:The drug-loaded hydrogel LDC/BetP-Gel was prepared through a sim-ple mixing process.Its physicochemical properties were characterized using electron microscopy,X-ray diffraction,Fouri-er-transform infrared spectroscopy,and rheological testing.In vivo gelation and injectability were evaluated through posi-tron emission tomography/computed tomography(PET-CT)imaging and pressure variation measurements.The in vitro drug release rate was determined using a direct release method,while the degradation rate was assessed using the residual weight method.A total of thirty BALB/c mice were randomly assigned to five groups:blank group,model group,4%LDC group,BetP-Gel group,and 4%LDC/BetP-Gel group.Pain behavior was assessed using the Up-Down method and Harg-reave's test.Biocompatibility was evaluated through HE staining,and the expression levels of inflammatory cytokines were measured via enzyme-linked immunosorbent assay(ELISA).RESULTS:The LDC/BetP-Gel hydrogel demonstrated ex-cellent drug encapsulation and sustained release properties.Behavioral assessments indicated that the LDC/BetP-Gel group exhibited significantly higher pain thresholds compared to the model group(P＜0.05),suggesting improved postop-erative pain relief.Furthermore,the LDC/BetP-Gel group showed a markedly prolonged analgesic effect compared to the LDC group(P＜0.05).HE staining confirmed the biocompatibility of the hydrogel.ELISA results revealed a significant re-duction in inflammatory cytokine levels in the LDC/BetP-Gel group 24 hours post-surgery(P＜0.05).CONCLUSION:The injectable hydrogel LDC/BetP-Gel possesses a dense and stable structure that enables effective drug loading and sus-tained release.Its ability to prolong anti-inflammatory and analgesic effects has been validated in a mouse model of acute incisional pain.

AIM:This study aims to investigate the sustained and stable drug release profile of the injectable hydrogel lidocaine(LDC)/betamethasone sodium phosphate hydrogel(BetP-Gel)and its effect on analgesic duration in a mouse model of acute incisional pain.METHODS:The drug-loaded hydrogel LDC/BetP-Gel was prepared through a sim-ple mixing process.Its physicochemical properties were characterized using electron microscopy,X-ray diffraction,Fouri-er-transform infrared spectroscopy,and rheological testing.In vivo gelation and injectability were evaluated through posi-tron emission tomography/computed tomography(PET-CT)imaging and pressure variation measurements.The in vitro drug release rate was determined using a direct release method,while the degradation rate was assessed using the residual weight method.A total of thirty BALB/c mice were randomly assigned to five groups:blank group,model group,4%LDC group,BetP-Gel group,and 4%LDC/BetP-Gel group.Pain behavior was assessed using the Up-Down method and Harg-reave's test.Biocompatibility was evaluated through HE staining,and the expression levels of inflammatory cytokines were measured via enzyme-linked immunosorbent assay(ELISA).RESULTS:The LDC/BetP-Gel hydrogel demonstrated ex-cellent drug encapsulation and sustained release properties.Behavioral assessments indicated that the LDC/BetP-Gel group exhibited significantly higher pain thresholds compared to the model group(P＜0.05),suggesting improved postop-erative pain relief.Furthermore,the LDC/BetP-Gel group showed a markedly prolonged analgesic effect compared to the LDC group(P＜0.05).HE staining confirmed the biocompatibility of the hydrogel.ELISA results revealed a significant re-duction in inflammatory cytokine levels in the LDC/BetP-Gel group 24 hours post-surgery(P＜0.05).CONCLUSION:The injectable hydrogel LDC/BetP-Gel possesses a dense and stable structure that enables effective drug loading and sus-tained release.Its ability to prolong anti-inflammatory and analgesic effects has been validated in a mouse model of acute incisional pain.