Acerca de la disolucion de tabletas de Fenitoina sodica

We studied the effect of the addition of microcrystalline cellulose and calcium phosphate excipients on three technological properties of Phenytoin sodium tablets: dissolution, hardness and ejection pressure. Tablets of pure Phenytoin and Phenytoin sodium of various formulations showed a fast dissolution at times less than 10 minutes with a subsequent decrease of the amount of drug dissolved. This decrease was greater when not boiled water was used as dissolution medium, compared to boiled water. We suggest to verify the minimal acceptable dissolution at times less than 30 minutes and not exactly at 30 minutes. The best dissolution was observed with tablets of pure Phenytoin sodium. This dissolution decreased as the concentration of the excipients in the formulation increased. The pure drug tablets showed very high ejection pressures (12 MPa), which diminished to acceptable values upon the addition of increasing quantities of microcrystalline cellulose (40% w/w 3.9 MPa). Tablet hardness was acceptable in all formulations and was greater as the concentration of microcrystalline cellulose in the formulation increased.