Prepraration and evaluation of sodium carboxymethyl starch as suspending agent in dry syrup

Abstract

The preparation and evaluation of sodium carboxymethyl starch which prepared as suspending agent from three native starches (glutinous rice starch, rice starch and tapioca starch) were studied. Modified glutinous rice starch (MGS), modified rice starch (MRS) and modified tapioca starch (MTS) were prepared by Filbert’s method to have degrees of substitution (DS) of 0.16, 0.26 and 0.38 , respectively. The results indicated that Filbert’s method gave MGS and MRS at DS 0.16 and 0.26, respectively. However, the decreasing of reaction time from 2 hours to 90 minutes would be performed in order to synthesize MTS with DS of 0.38. In order select optimum concentration of each prepared modified starches and Ultrasperse® 2000 (UT, commercial modified starch) as suspending agent, 10% w/v calcium carbonate suspension was prepared. The reconstitution time, redispersibility, sedimentation volume and viscosity of 10% w/v calcium carbonate suspension when using different type and concentrations of suspending were compared. It was found the optimum concentration of MGS, MRS, MTS and UT were 1.0, 2.0, 3.0 and 4.0% respectively. Then, the use of prepared modified starched and UT as suspending agent in dry syrups formulation of amoxicillin trihydrate and cephalexin monohydrate at the concentration of 125 mg/ 5ml was studied. Citrate buffer was used to control the pH of amoxicillin trihydrate and cephalexin monohydrate dry syrup at 6.0 and 4.5, respectively. The citrate buffer at the concentration of 0.05 M had slight effect on the stability and viscosity of formulation which stored at room temperature and in refrigerator ( 8.0± 1 °C) for 14 days. The preliminary result indicated that MTS was not appropriate as suspending agent in dry syrups, since the bubble was occurred after shaking. The stability study of amoxicillin trihydrate dry syrup using MGS, MRS, UT at 2.5%, 3.0% and 4.0% w/v, respectively, and cephalexin dry syrup using MGS, MRS, UT at 2.5%, 2.5% and 4.0% w/v, respectively, were performed by storage at room temperature and 45°C, 75% RH for 4 months. The evaluation of drug content and physicochemical properties was performed every month. The drug content and physicochemical properties of dry powder and reconstituted suspension remained unchanged. In addition, the short reconstitution time and good redispersibility of formulation were observed. The viscosity and drug content of formulation were slightly decreased when storage at room temperature and 45°C, 75% RH for 4 months.