Failure of hydrocortisone to alter acutely antipyrine disposition

The disposition of intravenously administered antipyrine in single doses of 40 mg/kg was studied in 3 dogs at 7:00 A.M. and 3 wk later at 7:00 P.M. Our purpose was to determine whether hydrocortisone differentially affected antipyrine disposition according to a circadian pattern. After each intravenous dose of antipyrine, saline was infused for 3 hr followed by intravenous hydrocortisone (2 mg/15 kg loading dose; 2 mg/15 mg/hr infusion for 3 hr). This regimen of hydrocortisone failed at either 7:00 A.M. or 7:00 P.M. to alter acutely antipyrine decay curves. Furthermore, in 4 normal male volunteers, no inflection in the salivary antipyrine decay curve occurred when hydrocortisone was injected 8 hr after antipyrine. In the human volunteers an intravenous injection of 3 mg was followed immediately by an additional 6 hr of continuous hydrocortisone infusion at 3 mg/hr. These experiments show that hydrocortisone alters the pharmacokinetics of previously administered antipyrine in neither dogs nor man.