Addition of Sugar Fatty Acid Esters to Digoxin Suppository and Its Prolonged Action

Rectal suppositories of digoxin were prepared from cacao butter containing 5 % of polysorbate 60 and 1, 2, or 5 % of sucrose fatty acid esters with HLB value of approximately 11 and 15 (SFAE-11, SFAE-15). Physical properties such as melting point, dissolution time and hardness of these suppositories were determind. Blood samples of rabbits were collected at 0.5, 1.5, 3.0, 4.5, 7.0 and 9.0 hours after rectal administration of digoxin (0. 3mg/kg). The plasma digoxin levels were determined by a radioimmunoassay method. Long lasting effect for digoxin suppositories containing SFAE-11 and SFAE-15 was estimated from the relative areas under the concentration-time curve over 0 to 9 hours, and the ratios between 0.5 hour value and 1.5 hour value of plasma digoxin concentration-time curve for digoxin suppositories containing 1, 2, or 5 % of SFAE-15 were 1.52, 2.14 and 2.23, respectively. The ratios for the suppositories containing 1, 2, or 5 % of SFAE-11, as determined by Formula 1 as standard, were 0.67, 0.87, and 1.23, respectively. The ratios between 0.5 hour value for Formula 1 to 7 was 0.55, 0.54, 0.70, 0.89, 0.77, 0.91, and 0.94, respectively.