New therapeutic indications based on the antiprogesterone action of RU 486 (Mifepristone) are emerging which require long term administration and raise the question of its safety because of the antiglucocorticoid action of the drug. A trial was designed to assess the antiglucocorticoid effect of RU 486, possible manifestations of peripheral cortisol deprivation, and the adrenocortical and corticotroph reserves. Ten normal male volunteers (aged 21-29 yr) were given RU 486 (200 mg/day) or placebo between 0800-0900 h for 8 consecutive days in a randomized, double blind, cross-over design, with a 1-month interval between the two periods. RU 486 induced overactivation of the pituitary-adrenal axis; baseline values (mean +/- SEM) before and at end of treatment were, respectively: 0800 h plasma cortisol, 147.3 +/- 15.5 and 257.6 +/- 8.8 ng/mL; 0800 h salivary cortisol, 5.8 +/- 1.2 and 15.2 +/- 0.8 ng/mL; nocturnal (2200-0800 h) urinary cortisol, 8.4 +/- 1.5 and 33.7 +/- 11.1 micrograms; and 0800 h plasma ACTH, 29.2 +/- 3.7 and 60.2 +/- 8.4 pg/mL. All of these variations were significantly different from those during placebo treatment (0.0001 < P < 0.03) and disappeared within 4 days after the end of treatment. A daily record of subjective clinical symptoms, body weight and temperature, blood pressure, and heart rate showed neither side-effects nor any significant variation during treatment. Blood electrolyte and eosinophil counts were unchanged; fasting blood glucose was slightly higher at the end of treatment (5.0 +/- 0.2 vs. 4.7 +/- 0.1 mmol/L; P = 0.04). The adrenocortical response to Cortrosyn (0.25 mg, im) was exaggerated during RU 486 treatment (P < 0.006): peak values before and at the end of treatment were, respectively: plasma cortisol, 272.5 +/- 15.2 and 347.1 +/- 20.6 ng/mL; and salivary cortisol, 17.0 +/- 2.2 and 31.1 +/- 3.1 ng/mL. Direct pituitary stimulation (100 micrograms ovine CRH, followed by 1 IU lysine vasopressin over 15 min) also induced exaggerated corticotroph and adrenocortical responses (P < 0.005); peak values before and at the end of treatment were, respectively: plasma ACTH, 147.7 +/- 24.6 and 254.0 +/- 41.3 pg/mL; and plasma cortisol, 231.6 +/- 7.3 and 319.2 +/- 12.3 ng/mL. These data show that 8-day treatment with 200 mg RU 486 daily induces a hormonally detectable antiglucocorticoid effect without clinical symptoms. This state results from reversible cortisol overproduction with preservation of adrenocortical and pituitary reserves.
PIP: At Cochin Hospital in Paris, France, ten 21-29 year old normal male volunteers received either 200 mg RU-486 per day or a placebo for 8 consecutive days between 8:00 and 9:00 in the morning, then went through a 28-day washout period before receiving what they did not receive the first time for 8 days. The researchers wanted to examine the antiglucocorticoid effect of RU-486, any evidence of peripheral cortisol deprivation, and the adrenocortical and corticotroph reserves. An assessment of potential risk of longterm administration of RU-486 is needed to determine whether it can be used to treat chronic diseases (e.g., meningioma and breast cancer). RU-486 was responsible for overreaction of the pituitary-adrenal axis (8:00 am plasma cortisol, 147.3 ng/mL vs. 257.6 ng/mL; 8:00 am salivary cortisol, 5.8 ng/mL vs. 15.2 ng/mL; nocturnal urinary cortisol, 8.4 mcg vs. 33.7 mcg; and 8:00 am plasma adrenocorticotropic hormone [ACTH] 29.2 pg/mL vs. 60.2 pg/mL). All these changes differed significantly from those during placebo treatment (0.0001 p 0.03). These changes no longer existed 4 days after the end of treatment. The men kept a daily record of subjective clinical symptoms, body weight and temperature, blood pressure, and heart rate, which did not indicate any side effects or any considerable variation during treatment. RU-486 did not affect blood electrolyte and eosinophil counts. Blood glucose levels during fasting were somewhat higher at the end of treatment (p = 0.04). During RU-486 treatment, the adrenocortical response to 0.25 mg of intramuscularly injected Cortrosyn was amplified (peak values before and after, plasma cortisol, 272.5 ng/mL vs. 347.1 ng/mL; 17 ng/mL vs. 31.1 ng/mL) (p 0.006). Direct stimulation of the pituitary resulted in exaggerated corticotroph and adrenocortical responses (p 0.005). These findings showed that a daily dose of 200 mg RU-486 causes a hormonally detectable antiglucocorticoid effect but no clinical symptoms.