Connexin43 mimetic peptide (Cx43MP) has been intensively investigated for its therapeutic effect in the management of inflammatory eye conditions, spinal cord injury, wound healing and ischemia-induced brain damage. Here, we report on a validated stability–indicating reversed-phase high performance liquid chromatography(RP-HPLC)method for the quantification of Cx43MP under stress conditions.These included exposure to acid/base, light, oxidation and high temperature. In addition, the degradation kinetics of the peptide were evaluated in bovine vitreous and drug-free human plasma at 37 ℃. Detection of Cx43MP was carried out at 214 nm with a retention time of 7.5 min. The method showed excellent linearity over the concentration range of 0.9–250μg/mL(R2≥0.998),and the limits of detection(LOD)and quantification(LOQ) were found to be 0.90 and 2.98 μg/mL, respectively. The accuracy of the method determined by the mean percentage recovery at 7.8, 62.5 and 250μg/mL was 96.79%, 98.25% and 99.06% with a RSD of<2.2%. Accelerated stability studies revealed that Cx43MP was more sensitive to basic conditions and completely degraded within 24 h at 37 ℃(0% recovery)and within 12 h at 80 ℃(0.34% recovery).Cx43MP was found to be more stable in bovine vitreous(t1/2slow=171.8 min)compared to human plasma(t1/2slow=39.3 min)at 37 ℃ according to the two phase degradation kinetic model. These findings are important for further pre-clinical development of Cx43MP.