| In this study, N-acetylcysteine activated carbon sustained-release microcapsules (NCSM) were prepared by emulsion crosslinking method. The preparation process was optimized, and the pharmacokinetics and pharmacokinetic parameters were studied. Further studies is on microcapsules in the treatment of liver fibrosis in rats by oral administration, compared with single N-acetylcysteine and silybin, a commercial classic anti-hepatic fibrosis drug.Objective:N-acetylcysteine (NAC), a precursor of glutathione, has received increasing interest in the treatment of liver fibrosis due to its antioxidant activity. However, the clinical route of administration of NAC is intravenous injection, but because of its rapid metabolism in the body, it can not form a stable and lasting blood drug concentration, and the clinical application of drug delivery is poor.NAC has a high first-pass effect, and the current route of administration is intravenous.NCSM could eliminate the first-pass effect, with the slow release by the role of the digestive tract, form a more stable plasma concentration, prolong drug action, open up oral route of administration with N-acetylcysteine in the treatment of liver fibrosis, and increase patient compliance.Methods: ? Pre-formulation study. A method for the determination of N-acetylcysteine was established by high performance liquid chromatography (HPLC). Preparation of activated carbon loaded drug, and screening gelatin target capsule. The use of emulsion crosslinking method to establish preparation method for N-acetylcysteine activated carbon sustained-release microcapsules. ?Optimization of the preparation technology of NCSM. The orthogonal experiment L9 (34) was used to study the effects of four factors, such as drug loading ratio, gelatin concentration, stirring speed and emulsifier concentration, on the drug loading of active carbon, entrapment efficiency, particle size and distribution. The optimum microcapsule preparation technology was obtained and the quality of NCSM was evaluated. ? Tolnvestigate therelease of NCSMin vivo and in vitro, to evaluate the effect of NCSM. The quality standard of the NCSM was preliminarily established.?To observe the effect of NCSM by oral administration on rat liver fibrosis induced by carbon tetrachloride (CCl4).CCl4-induced rat liver fibrosis model was established, and the rats were given NCSM high, middle and low dose of 80mg·kg-1·D-1,40mg·kg-1·D-1, 20mg·kg-1·D-1 (calculated according to acetylcysteine), NAC and silybinas the positive control drug by gavage administration. Rats were sacrificed after 8 weeks of treatment. The therapeutic effects of different doses of NCSM, NAC and silybin on liver fibrosis in rats were compared, and the effect on the hepatic fibrosis indexes, hepatic fibrosis pathology and signaling pathway of fibroblasts (TGF-?1/T?R-I/Smad2/3) in rat liver fibrosis were studied, to evaluate the therapeutic effect of oral NCSM on liver fibrosis model rats.Results: ?The preparation technology of N-acetylcysteine activated carbon sustained-release microcapsules was studied by selecting prescription and gelatin as capsule material. ?The orthogonal experiment L9 (34) showed that the effect of the encapsulation effect was in the order of drug loading ratio (ratio of drug and gelatin)> stirring speed> gelatin concentration>emulsifier concentration, with drug loading ratio of 1:1, gelatin concentration of 15%, stirring speed of 1000 r·min-1 and emulsifier (Span-80) concentration of 2%. Under the conditions of preparation, the NCSM had a uniform particle size, high drug loading and high entrapment efficiency. The results of the verification test show that this preparation process of the microcapsule was stable, and confirmed as the best preparation technology. Three batches of NCSM were prepared. The average particle size was 110.4?m±13.59?m. The average encapsulation efficiency was 78.1% and the average drug loading was 15.9%. ?The in vitro release results showed that NCSM released 20.4% in 1 h and 69.2% in 24 h, which was consistent with the first order kinetic equation. The pharmacokinetic results in mice showed that t1/2 of oral microcapsules was 3.32 times that of NAC and AUC(o-24) was 1.18 times that of NAC, with a significant slow release effect. ?CCl4-induced rat liver fibrosis model was successfully established. The pathological changes of liver tissue were observed by HE staining and reticular fiber staining. The degree of hepatic fibrosis was grade ?-?, and immunohistochemistry showed that TGF-?1/T?-R1 and Smad2/3 were abundantly. Immunohistochemistry expressed. Immunohistochemistry showed that TGF-?1/T?R-? and Smad2/3 expression were decreased in the NCSM group, and the NCSM high dose group (80 mg·kg-1·D-1) expression was significantly different (p<0.05).Conclusion:N-Acetylcysteine activated carbon sustained-release microcapsules prepared by emulsion crosslinking method, with uniform particle size, stable drug loading and entrapment efficiency. Compared with NAC, the time of plasma concentration maintenance was significantly increased and the bioavailability was significantly improved by oral administration. NCSM has a better therapeutic effect on liver fibrosis in rats, than the effect of NAC and the control drug silybin. The mechanism may be related to obvious inhibitory effect on intracellular fibroblast signaling molecules TGF-?1/T?R-? and Smad2/3 in rat liver fibrosis. |
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