Formulation development of film coated tablets containing malvastrum coromandelianum extract

Abstract

The spray-dried powder of Malvastrum coromandelianum water extract has been reported to be able to lower blood sugar for diabetic rabbits. It was also utilized for treating diabetic patients. However, the dried powder turned from pale brown into damp dark brown mass after storage for a few days, even filled into hard gelatin capsule. Therefore, the purpose of this study was to develop film coated tablets of high dose of Malvastrum coromandelianum powder. The spray-dried powder was evaluated for particle size, flow, and density. The core tablets were produced on a single-punch tablet press by direct compression method and using various fillers and lubricants to obtain optimal core tablet formulation. The coating process was performed using hydroxypropylmethylcellulose (HPMC), chitosan and Eudragit E100 as film former by Thai coater. These tablets were evaluated for friability, hardness, disintegration and % drug dissolved at 60 minutes. The content was analyzed by high performance liquid chromatography. The influences of type of polymeric films HPMC, chitosan and Eudragit E100 on adhesive strength and moisture protection were evaluated both initially and accelerated conditioned (45 ± 2 ℃ /75 ± 5 % RH for 4 months). The results found Malvastrum coromandelianum spray-dried powder exhibited poor flow property in spite of narrow sizes and spherical shape particles with rough surface and aggregation in cluster. The selected core tablets showed satisfactory properties, having light brown color with smooth and shiny surface. HPMC and Eudragit E100 film coated tablets showed good appearance and physical properties of high mechanical resistance with low moisture sorption. The chitosan coated tablets exhibited the highest moisture sorption and color change. The concentration film coated significantly influenced both moisture and dissolution pattern while the type of polymer had slight effect on disintegration time. After storage at accelerated condition, the content of both HPMC and Eudragit E100 coated tablets was still within the standard of pharmacopoeia and good appearance. The percent remaining of the active compounds was 90.41% and 90.65% of the initial content as HPMC5 and PMC2, respectively. However, HPMC coated tablets showed poor appearance of swelling after storage for 6 months. In conclusion, Eudragit E100 film coated tablets of high dose of Malvastrum coromandelianum extract could be prepared with satisfactory properties and stability.