Egg shell powder as a potential direct compression excipient in tablet formulation

Background: There is abundance of egg shells which comes as waste from the food industry. Development of this waste into pharmaceutical excipient will have economic gain and provide alternative source of raw materials in tablet manufacture.

Objective: This work is aimed at developing eggshell powder as a direct compressible excipient in tablet manufacture.

Methods: Eggshells collected as wastes from eateries in Enugu State, Nigeria were comminuted, bleached with sodium hypochlorite, washed with water, air-dried, pulverized and sterilised by dry heat. Microbial counts were carried out. Heavy metal analysis was done by atomic absorption spectrometry. Avicel PH 101 for used as a model direct compression excipient. Mixtures of the eggshell powder and Avicel PH 101 in the ratios of 1:0, 0:1, 1:1 and 2:1 respectively were used in preparing ascorbic acid granules and tablets. The flow properties of the granules and tablet properties were evaluated. A step-wise optimisation approach was employed to get the batches with no defects, the least weight and content variation, least friability, hardness in the range of 4-7 kgf, and highest excipient dilution.

Results: The moisture content of the egg-shell powder was 0.68% and microbial analyses revealed compliance with official standards. Heavy metal analysis showed Lead (0.092%), Chromium (0.332%), Copper (0.111%), Iron (2.690%), Cadmium (0.390%), Nickel (1.313%), Arsenic (2.988%), Mercury (0.187%), Zinc (0.705%) and Manganese (0.424%). The eggshell powder had better flow than avicel PH 101. The batch with the best tablet properties selected according to pre-set parameters above contains 30% drug bulked with 1:1 eggshell/avicel pH 101 mixture.

Conclusion: Eggshell powder can serve as a direct compression agent in tablet manufacture.