Studies on Complexes. XI. : Effect of Complex Formation on Drug Absorption from Alimentary Tract. (2)

Effect of complex formation on the absorption of drugs was investigated after oral administration to rabbits and the results were compared with those in the previous report using perfusion method by rat small intestine. Blood concentrations of antipyrine (salicylic acid), salicylamide (nicotinamide), aminopyrine (salicylic acid), salicylic acid (antipyrine), and salicylic acid (aminopyrine) were compared with or without drugs in parentheses after oral administration in solution or suspension. It was found that (a) the results after oral administration coincided well with those using the perfusion method, (b) salicylic acid reduced the blood concentration of antipyrine during the first one hour, (c) as the blood concentrations of salicylamide with nicotinamide, aminopyrine with salicylic acid, and salicylic acid with aminopyrine were higher than those of control after oral administration in suspension, it may be a good method for increasing the initial blood concentration of very slightly soluble drugs after oral administration in solid with the solubilizing compounds, and (d) aminopyrine gave constant blood concentration of salicylates for 6 hours and this was explained by the correlation with the fraction eliminated as free salicylic acid in urine.