Disposition of a new steroidal anti-inflammatory agent, deflazacort, in rat, dog and man

The physiological disposition of a new steroid anti-inflammatory agent, deflazacort, was examined in rat, dog and man following 5 mg/kg doses to the animals, and 50 mg to humans. The administered radiocarbon [2'-14C]-deflazacort), is rapidly and extensively absorbed into the general circulation in rat and man, whereas the bioavailability in the dog is low. The terminal plasma half-life for radioactivity elimination was, on the average, 11, 15 and 28 hr in rats, dogs and man, respectively. Urinary excretion was the predominant route of 14C elimination in the rat (-54% of the dose) and in man (-68% of the dose), whereas in the dog the majority of the dose was eliminated via the feces (82%). Tissue distribution studies in the rat did not show target organs, with the exception of the blood cells. Studies of binding to plasma proteins of the 21-desacetyl deflazacort, demonstrate in all the species a rather low level of binding of non-saturable type.