Abstract
A study was made by the in situ recirculating perfusion technique as to the effect of urea (0.1, 0.5, 1.0M) on the absorption of salicylic acid, benzoic acid and aminopyrine in rat intestinal tract. The addition of 0.5 or 1.0M urea resulted in increased drug permeability of the gill of gold fish, while that of 1.0M urea significantly decreased intestinal drug absorption clearance. With urea added to a perfusate, its osmotic pressure was elevated and the water flux from the intestine to the blood was decreased. A significant correlationship existed with a positive regression coefficient between water flux and clearance. Similarly, both water flux and clearance were reduced by adding NaCl so as to give the same tonicity as 1.0M urea. This effect was not significantly different from that of adding 1.0M urea. From these observations it is concluded that urea has no such effect in rat intestines as is observed in gold fish.
