ABSTRACT
The effect of prolonged oral administration of nifedipine [four weeks] in three dose levels 1, 3 and 10 mg/kg/day] as well as the effect as measured on the third day following abrupt withdrawal of the drug on plasma levels of adenocorticotrophic hormone [ACTH] and serum levels of cortisoly triiodothyromine [T3] thyroxine [T4], insulin, glucose and free fatty acids [FFAs] was studied in normal rabbits. Nifedipine decreased plasma ACTH serum insulin and FFAs levels at the three doses used. A decrease of serum T[3] level occurred at the 1 mg/kg dose. Meanwhile it increased serum cortisol at 10 and 3 mg/kg doses and serum glucose at the 10 mg/kg dose. Withdrawal of nifedipine still showed an increase in serum cortisol at the 10 mg/kg dose as a result of persistence of its pharmacodynamie effect. Also it increased serum FFAs at the 10 and 3 mg/kg doses; while a decrease of serum T[3] was noted at the 10 and 3 mg/kg doses. A decrease of serum insulin at the three doses used occurred on the third day after abrupt cessation of the drug