Preparation Of Tetrandrine Composite Particles Based On The Molecules Inclusion Mechanism And Study In The Treatment Of Pulmonary Fibrosis

Pulmonary fibrosis is a kind of interstitial lung disease with the features of progressive and often fatal dyspnea.However,because the combined treatment of anti-inflammatory therapy and immunosuppressive therapeutic strategy did not improve outcome,even increased mortality,it is urgent to develop new medicines and preparations.Tetrandrine is the major active constituent of Chinese herbal tetrandrine,which has already applied clinically to treat rheumatism,lung cancer,and silicosis.Unfortunately,the tetrandrine tablets have poor solubility and are not easily absorbed by oral administration,resulting in low bioavailability and poor efficacy.Furthermore,due to extensive pharmacological effects and accumulation in the liver,it is hard to meet safety and efficacy medication requirements in the treatment of pulmonary fibrosis after long-term intravenous administration.In this work,tetrandrine-hydroxypropyl-?-cyclodextrin inclusion compound was developed for the treatment of pulmonary fibrosis via inhalation administration.Cyclodextrin is a non-toxic excipient and well-tolerated by oral,intravenous and inhalation administration.Its microscopic structure allows cyclodextrin to form non-covalent inclusion complexes with lipophilic organic compounds and improves their aqueous solubility and stability.Tetrandrine-hydroxypropyl-?-cyclodextrin was prepared by the freeze-drying method and identified using differential scanning calorimetry,X-ray diffraction and fourier transform infrared spectrum.The stoichiometric ratio(1:1)and the apparent stability constant(Ks=83.12 M-1)of the complex were determined by means of the phase-solubility diagram.The semi-industrial production of the tetrandrine-hydroxypropyl-p-cyclodextrin complex was carried out in saline solution followed by high-pressure homogenization.The transmission electron microscope test results indicated that high-pressure homogenization produced nanosuspension with particle diameter of 50 nm.Eventually,the nanosuspension was introduced as an aerosol by use of the air-compressing nebulizer,spray into a respirable mist liquid bead via a mouthpiece.The release profile,lung deposition characteristics in vitro and tissue distribution of the inclusion compound were investigated as well.Subsequently,the therapeutic efficacy of the inhalable tetrandrine-hydroxypropyl-?-cyclodextrin inclusion was evaluated on bleomycin-induced pulmonary fibrosis murine model.Animal survival,hydroxyproline content in the lungs,protein expression and lung histology were detected in animal studies.The results showed that inhalation of tetrandrine-hydroxypropyl-?-cyclodextrin alleviated inflammation and fibrosis,limited the accumulation of hydroxyproline in the lungs,regulated protein expression in pulmonary fibrosis development and improved postoperative survival.The aerosol inhalation of tetrandrine-hydroxypropyl-?-cyclodextrin inclusion nanosuspension achieved optimal therapeutic results according to the results in the treatment of pulmonary fibrosis.The aerosol treatment has been considered as an appropriate method for delivering drugs to pulmonary lesions non-invasively.Based on the above mentioned,enhancing the efficacy of pulmonary fibrosis treatment by local pulmonary delivery of tetrandrine with low systemic exposure and low side effects is favored.Based on the similarity theory,we also attempted to develop a tetrandrine-lysozyme complex and evaluated the stability of tetrandrine adducts with lysozyme by fluorescence spectroscopy in order to determine the potential application of lysozyme in tetrandrine delivery.Molecular modeling studies showed that the free binding energy of drug-protein complex was-5.36 kcal/mol.Hydrophobic contacts stabilize tetrandrine-protein conjugation and play an important role in drug-protein complex formation.Inhalation powders were prepared with the technology of spray drying Spray-dried microparticles were tested for performance of powders with the powder rheometer and measured for aerodynamic parameters with the cascade impactor.Scanning electron microscope observation showed that the tetrandrine-lysozyme powders displayed a wrinkled ball associated with an appropriate mass median aerodynamic diameter(4.94 ?m).These experimental results show that that the amyloid fibrils can potentially be used for delivery of tetrandrine in pulmonary system and release drugs consistently and locally to enhance the therapeutic effect of pulmonary fibrosis.