[The long-term therapy of hypothalamic-hypophyseal Cushing's syndrome with mitotane (o,p'-DDD)]

Drug treatment of hypothalamic-pituitary Cushing's syndrome is indicated if standard surgical intervention is not possible or has failed. The question arises whether, after unsatisfactory treatment with various adrenostatic drugs, mitotane (o,p'-DDD), used against adrenal cortical cancer, is efficacious and free of significant side effects when used long-term.

The results of long-term administration of mitotane to six patients, including one pregnant woman, were analysed retrospectively. After a moderate initial dosage of 3.0 g daily a maintenance dose of minimally 0.5 g per week was given or the treatment temporarily interrupted. The concentration of urinary free cortisol served as the main criterion of efficaciousness, together with the clinical course. The plasma concentrations of cortisol, aldosterone and ACTH were also determined, as well as routine clinicochemical parameters.

Cortisol excretion became normal in all patients between the 2nd and 10th treatment month, falling from 919 +/- 621.3 nmol daily in the six months before treatment to 162 +/- 93.0 nmol daily in the third six-month treatment period (mean +/- standard deviation). Normal cortisol excretion and regression of symptoms was noted, dose-dependent, as long as the 12th year after start of treatment. Adrenocortical insufficiency occurred in one patient and at times required hormone substitution, followed by lasting remission without special treatment. Significant side effects were not observed other than a reversible increase in gamma-glutamyl transpeptidase.

Mitotane proved to be an efficacious drug which in exceptional cases can be used without significant side effects in low dosage for the long-term treatment of hypothalamic-pituitary Cushing disease.