Local Administration Of Curcumin - Piperine Compound Self - Microemulsification Ulcerative Colitis

Objective:In the study, curcumin (CUR) and piperine (PIP) were co-encapsulated into the nanoformulation called self-microemulsifying drug delivery system (SMEDDS) in order to improve the water-solubility and stability of CUR, and avoid the degradation of it in the intestinal mucosal surface. CUR-PIP-SMEDDS was dosed through colon local drug delivery to increase the local concentration of CUR in the surface colonic mucous epithelial cell and enhance the efficacy for ulcerative colitis (UC) therapy, in the expectation of providing new ideas and methods for researching and developing safe and effective new drugs for UC treatment.Methods:Simplex lattice design was constructed using optimal oil phase, surfactant and cosurfactant concentration as independent variables, and the CUR and PIP were used as model drugs to optimize CUR-PIP-SMEDDS formulation. In the present study, the drug loadings of CUR and PIP, mean particle size of CUR-PIP-SMEDDS emulsion droplet were made as indicators, and the experiment design, model building and response surface analysis were establish using Design Expert software to optimize and verify the optimal composition of SMEDDS formulation. The quality of CUR-PIP-SMEDDS was evaluated by observing the appearance status, transmission electron microscope micrographs and determining particle diameter, zeta electric potential, drug entrapment efficiency and drug loading of it. Meanwhile, the vitro stability of CUR-PIP-SMEDDS in colon tissue was determined. Then anti-colitis activity of CUR-PIP-SMEDDS was evaluated on a model of DSS-induced ulcerative colitis in male BALB/c mice. Its therapeutical effects for UC therapy was investigated via retention enema administration that simulates the action principle of colon targeted preparations. Using 5-aminosalicylic acid (5-ASA) as a control, disease activity index scoring, colon length, histopathology scoring, colonic tissues activities of myeloperoxidase (MPO), colon tissues of malondialdehyde (MDA) content as well as colon tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) level were investigated to confirm the model and unravel any possible protection exerted by CUR-PIP-SMEDDS. Finally, a week after continuous retention enema administration, the general status, behavioral sign, mental status, as well as the colon local appearance, general form and histopathological changes of colonic mucosa was observed to preliminarily evaluate the topical irritation of auxiliary materials and drugs to colonic mucosa.Results:Capryol 90, Cremophor RH40 and Transcutol HP were chosen as oil phase, surfactant and co-surfactant respectively for CUR-PIP-SMEDDS formulation, and the optimal formulation of it was Capryol 90-Cremophor RH40-Transcutol HP (10:60:30, w/w/w). The appearance of CUR-PIP-SMEDDS remained clarified and transparent, and the microemulsion droplets appeared spherical without aggregation. The mean size of microemulsion droplets formed from CUR-PIP-SMEDDS was (15.33±0.80) nm, the drug loading of SMEDDS for CUR and PIP were (40.90±0.70) mg·g-1and (0.97±0.02) mg·g-1, respectively, and the drug entrapment efficiency were (94.98±2.37)% and (90.96±2.72)%, respectively. After incubation for 24 hours at 37℃, we found free CUR, CUR-PIP mixture and CUR-PIP-SMEDDS degraded by 19.93%,12.67% and 10.50% respectively in the artificial colon fluid. The degradation of CUR followed apparent first-order kinetics equation and the half-life were 19.67 h,57.87 h and 75.23 h respectively in the artificial colon fluid. After incubation for 8 hours at 37℃, we found free CUR, CUR-PIP mixture and CUR-PIP-SMEDDS degraded by 19.96%,14.49% and 4.63% respectively in the mice colon tissue homogenate. We demonstrated that CUR-PIP-SMEDDS really could target the injured epithelium of colon on DSS-induced colitis mice through retention enema administration, as shown by remarkable improvements in clinical symptoms, including mental status, glossiness of skin, body weight, as well as the general situation of defecation and activity, and significant reduction in DAI and histopathological lesion, such as hyperaemia, edema, anabrosis and inflammatory cell infiltration of mice colon. We also found CUR-PIP-SMEDDS could downregulate inflammatory mediators such as MPO activity, MDA content, as well as TNF-αand IL-6 levels. CUR-PIP-SMEDDS (retention enema administration) has an equivalent effect to positive control medicine of 5-ASA in maintaining remission of UC, while the therapeutic effects of CUR-PIP-SMEDDS (intragastric administration) were relatively weaker, and CUR-PIP 1%(wt/vol) CMC-Na (retention enema administration) exerted the weakest efficacy. Irritative experiment on mucosa has shown that auxiliary materials and drugs had no significant effects on the systemic reaction, breath, mental status, as well as growth and development of healthy mice after continuous retention enema administration for a week. Furthermore, there were no marked local hyperemia edema, abnormal secretions, pathological damage, erosion and necrosis of colon. Irritative reaction score was 0-0.4, which indicated no mucosa irritation.Conclusions:In the present study, a simplex lattice experiment design combining pseudo-ternary phase diagram was adopted to develop the optimal CUR-PIP-SMEDDS formulation, which can significantly improve the water-solubility and stability of CUR and has an excellent therapeutic effect on UC without mucosa irritation. Taken together, these findings can provide experimental basis and research reference to development specific effective material base, clear mechanism of action, safe and effective clinical application, as well as stable and controllable quality for compound oral colon-specific formulation of CUR. Meanwhile, the study will provide new ideas and methods for developing effective new drugs for UC therapy.