Evaluation of Acid-Modified Ethiopian Potato (Plectranthus edulis) Starch as Directly Compressible Tablet Excipient

Ethiopian potato is one of the tuber-bearing members of the family Lamiaceae. It is an indigenous crop in Ethiopia and important source of starch. Unprocessed native starches are structurally weak and functionally restricted for application in pharmaceutical technologies. Consequently, starch is usually modified either chemically or physically to make it convenient for industrial use. The aim of the study was to prepare and characterize acid-modified Ethiopian potato starch (AMEPS) and evaluate its functionality as a direct compressible excipient in tablet formulations. The extracted starch from Ethiopian potato tuber was modified using 6% HCl concentration for 8 days, then dried using oven and spray drying techniques, and subsequently evaluated and compared with the native Ethiopian potato starch (NEPS) and S1500® as a direct compressible excipient. Acid modification of the NEPS decreased the moisture content and swelling power while increased the percent solubility. The X-ray diffraction revealed that both the NEPS and AMEPS have B-type crystal patterns. The AMEPS showed improved flowability compared to the NEPS. This improvement was further enhanced by the spray drying process. The compactability study revealed that the tensile strength of spray-dried AMEPS (16.76 kg/cm(2)) was significantly higher than that of the spray-dried NEPS (7.07 kg/cm(2)) and S1500® (11.66 kg/cm(2)). The AMEPS was less sensitive to lubricants compared to the NEPS and Starch 1500®. Similarly, the dilution potential of the AMEPS was superior to the NEPS and S1500®. The AMEPS accommodated up to 50% of paracetamol while the NEPS and S1500® were able to hold only up to 30%. Pharmacopoeial specifications for disintegration and dissolution were met by the paracetamol tablets prepared by AMEPS. Thus, considering all the results obtained, spray-dried AMEPS could be a potential alternative directly compressible tablet excipient.