A micellar solution of sodium taurocholate has been shown to increase the solubility of cortisol and prednisolone crystals in vitro. That this enhanced solubility confers little physiological advantage to the rat has been demonstrated in in vivo studies on the intestinal absorption of these compounds. Tritiated crystals of cortisol and prednisolone were delivered intraduodenally to rats with complete biliary diversion receiving an intraduodenal infusion of either 37 mm taurocholate or normal saline. The excretion of the metabolic products of the steroids in bile and urine was used as a measure of the intestinal absorption of the parent compound. Excretion was greater in the first 2 hr after the administration of either cortisol or prednisolone in rats receiving bile salts than in bile salt-deficient animals. By 4 hr, however, no significant differences were found in the excretion values between the two groups of rats. More than 70% of the administered steroid was recovered in bile and urine within 4 hr in animals with a complete bile-salt deficit. Despite the demonstration, in vitro, that both steroid compounds are bound by cholestyramine, no significant decrease in the intestinal absorption of cortisol was observed when either cholestyramine or an antacid containing aluminum hydroxide were administered concomitantly.
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