Study On Sustained-release Film Of Lidocaine

To keep plasma-drug Concentration, low dose of local anesthetieo must be given frequently. When large dose is given to suffers, C max will be higher than therapeutic window, that will lead to side effects. Otherwise, patients can not effectively alleviate from pain. So clinical treatments need a sustained-release local anesthetic agents. The design of microspheres film in this paper is such a formulation. The film designed in this paper is such a formulation. Chitosan-coated microspheres can achieve the the first sustained-release effect, and then Chitosan-PVA film can achieve the second sustained-release effect. Lidocaine was chosen as a model drug.The content of Lidocaine was monitored by Ultraviolet spectrophotometry. For Lidocaine physiological saline solution, at the wave length of 262 nm, the standard curves of Lidocaine is linear over the range of 0.1-0.6 mg/ml, and the equation of standard curves is Y=1.0054X+0.0413, r=0.9996; The average recovery rate(n=9) is 99.40%, RSD is 0.54%; It is stable within 4 days and RSD=0.50%.We used cross-linking, spray drying, spray drying and curing three methods, prepared microspheres pespectively. Spray drying and curing method were chosen at last by comparing drug loading, encapsulation efficiency, drug release rate.And through orthogonal experiment L9 (32), curing time and concentration of STPP solution were inspected to determine the best preparation method. Method to make spray drying microspheres: Chitosan lactic acid solution5.0 g/L, m(Lidocaine): m(Chitosan)1:4, The solutions were sprayed by a 0.7 mm nozzle at a rate of 1.5 ml/min in a Büchi-B290 spray dryer. The air flow rate is 28 m3/h, Inlet temperature is 120oC and the outlet temperature sway between 70℃and 80℃. Curing method: use NaCl as dispersant, first mix microspheres and NaCl evenly, and then curing 5 min in STPP (0.5%) solution, separate product, dry at 60℃, the final product is yellow powder.The prescription and preparation method of sustained-release film was determined by orthogonal experiment L9 (34). The prescription is:microspheres1.0 g, PVA 2.0 g, chitosan 0.5 g, glycerol 10.5%, water 100 ml. Preparation method: mix PVA solution, chitosan solution, glycerin and drug together, remove the bubble, dry at 60℃and take off the film.Prepare three batches of sustained-release films, the average loading rate is 3.60%, the film formation uniform appearance, flexibility and hardness are appropriate and easy to take off. Lidocaine can sustainably release 60 hours.