Adrenocorticotrophic hormone (ACTH) responsiveness to ghrelin increases after 6 months of ketoconazole use in patients with Cushing's disease: comparison with GH-releasing peptide-6 (GHRP-6).

BACKGROUND: In Cushing's disease (CD), adrenocorticotrophic hormone (ACTH)/cortisol responses to growth hormone secretagogues (GHS), such as ghrelin and GHRP-6, are exaggerated. The effect of clinical treatment of hypercortisolism with ketoconazole on ACTH secretion in CD is controversial. There are no studies evaluating ACTH/cortisol responses to GHS after prolonged ketoconazole use in these patients. OBJECTIVE: To compare ghrelin- and GHRP-6-induced ACTH/cortisol release before and after ketoconazole treatment in patients with CD. DESIGN/PATIENTS: Eight untreated patients with CD (BMI: 28.5 +/- 0.8 kg/m(2)) were evaluated before and after 3 and 6 months of ketoconazole treatment and compared with 11 controls (BMI: 25.0 +/- 0.8). RESULTS: After ketoconazole use, mean urinary free cortisol values decreased significantly (before: 613.6 +/- 95.2 nmol/24 h; 3rd month: 170.0 +/- 27.9; 6th month: 107.9 +/- 30.1). The same was observed with basal serum cortisol (before: 612.5 +/- 69.0 nmol/l; 3rd month: 463.5 +/- 44.1; 6th month: 402.8 +/- 44.1) and ghrelin- and GHRP-6-stimulated peak cortisol levels (before: 1183.6 +/- 137.9 and 1045.7 +/- 132.4; 3rd month: 637.3 +/- 69.0 and 767.0 +/- 91.0; 6th month: 689.8 +/- 74.5 and 571.1 +/- 71.7 respectively). An increase in basal ACTH (before: 11.2 +/- 1.6 pmol/l; 6th month: 19.4 +/- 2.7) and in ghrelin-stimulated peak ACTH values occurred after 6 months (before: 59.8 +/- 15.4; 6th month: 112.0 +/- 11.2). GHRP-6-induced ACTH release also increased (before: 60.7 +/- 17.2; 6th month: 78.5 +/- 12.1), although not significantly. CONCLUSIONS: The rise in basal ACTH levels during ketoconazole treatment in CD could be because of the activation of normal corticotrophs, which were earlier suppressed by hypercortisolism. The enhanced ACTH responses to ghrelin after ketoconazole in CD could also be due to activation of the hypothalamic-pituitary-adrenal axis and/or to an increase in GHS-receptors expression in the corticotroph adenoma, consequent to reductions in circulating glucocorticoids.

Effectiveness of cabergoline in monotherapy and combined with ketoconazole in the management of Cushing's disease.

The expression of dopamine receptor subtypes has been reported in corticotroph adenomas, and this finding support the possibility for medical treatment of Cushing's disease (CD) with dopamine agonists when conventional treatment has failed. The aim of this study was to evaluate the effectiveness of cabergoline (at doses of up 3 mg/week), alone or combined with relatively low doses of ketoconazole (up to 400 mg/day), in 12 patients with CD unsuccessfully treated by transsphenoidal surgery. After 6 months of cabergoline therapy, normalization of 24 h urinary free cortisol (UFC) levels occurred in three patients (25%) at doses ranging from 2-3 mg/week, whereas reductions ranging from 15.0 to 48.4% were found in the remaining. The addition of ketonocazole to the nine patients without an adequate response to cabergoline was able to normalize UFC excretion in six patients (66.7%) at doses of 200 mg/day (three patients), 300 mg/day (two patients) and 400 mg/day (one patient). In the remaining patients UFC levels did not normalize but a significant reduction ranging from to 44.4 to 51.7% was achieved. In two of the six responsive patients to combination therapy, the weekly dose of cabergoline could be later reduced from 3 to 2 mg. Our findings demonstrated that cabergoline monotherapy was able to reverse hypercortisolism in 25% of patients with CD unsuccessfully treated by surgery. Moreover, the addition of relatively low doses of ketoconazole led to normalization of UFC in about two-thirds of patients not achieving a full response to cabergoline.