Cetirizine dihydrochloride loaded microparticles design using ionotropic cross-linked chitosan nanoparticles by spray-drying method.

To control the release rate and mask the bitter taste, cetirizine dihydrochloride (CedH) was entrapped within chitosan nanoparticles (CS-NPs) using an ionotropic gelation process, followed by microencapsulation to produce CS matrix microparticles using a spray-drying method. The aqueous colloidal CS-NPs dispersions with a drug encapsulation efficiency (EE) of <15%, were then spray dried to produce a powdered nanoparticles-in-microparticles system with an EE of >70%. The resultant spherical CS microparticles had a smooth surface, were free of organic solvent residue and showed a diameter range of 0.5~5 µm. The in vitro drug release properties of CedH encapsulated microparticles showed an initial burst effect during the first 2 h. Drug release from the matrix CS microparticles could be retarded by the crosslinking agent pentasodium tripolyphosphate or the wall material. The technique of 'ionotropic gelation' combined with 'spray-drying' could be applicable for preparation of CS nanoparticlesin-microparticles drug delivery systems. CS-NPs based microparticles might provide a potential micro-carrier for oral administration of the freely water-soluble drug--CedH.

[Changes of amino acids neurotransmitters in striatum of hemi-parkinsonian rhesus monkey after high frequency stimulation of subthalamic nucleus].

OBJECTIVE: To investigate the influence of high frequency stimulation of the subthalamic nucleus on the levels of amino acids neurotransmitters in striatum of hemi-parkinsonian monkeys. METHODS: Two rhesus monkeys were successfully prepared for the subsequent microdialysis sessions. Collecting the dialysate before turning on the pulse generator, and collecting at 1 week, 1, 8 and 12 months after high frequency stimulation of the subthalamic nucleus. The level of Glu, GABA and Tau were determined by high performance liquid chromatography and fluorometric detection (HPLC-FD). RESULTS: After high frequency stimulation (HFS), PD symptoms of monkeys significantly improved. The levels of Glu in putamen and caudate nucleus of electrodes side at 1 week, 1, 8 and 12 months were increased significantly. The levels of GABA in putamen and caudate nucleus of electrodes side at 1 week, 1 month increased significantly compared with before turning on the pulse generator while decreased at 8, 12 months. The level of Tau in putamen and caudate nucleus increased significantly. CONCLUSION: Long-term STN HFS can increase the level of glutamate and taurine, while decrease the level of GABA in putamen and caudate nucleus of electrodes side. It improves symptoms of hemi-parkinsonian rhesus monkey significantly.