Endocrine Abstracts

Acromegaly is a rare endocrine disorder caused by growth hormone (GH) secreting pituitary adenoma. The treatment of choice is transsphenoidal surgery. In patients with persistent disease after surgery medical therapy is recommended. First-line medical treatment include first generation long-acting somatostatin analogs: octreotide LAR and lanreotide autogel. Recently, pasireotide – a second generation somatostatin analog has been investigated in patients with acromegaly.

The aim of this study was to compare the effectiveness of the single-dose of short-acting somatostatin analogs: octreotide vs pasireotide in patients with active acromegaly after surgical debulking who were resistant to first generation long-acting somatostatin analogs.

Eighteen patients after debulking surgery without biochemical control of acromegaly on medical therapy were enrolled in the study. All patients had short-acting octreotide and pasireotide administered on different days. GH concentration was measured before and 60, 120 and 180 min after drug administration. Nadir GH concentrations and decreases in GH concentrations were compared.

Nadir GH values in octreotide test were reached 60 min after drug administration, while in pasireotide test – 180 min after drug administration. The median nadir GH concentration was 2.765 μg/l (IQR: 1,885–4.07) vs 1.51 μg/l (IQR: 0.95–2.555) respectively, P<0.001. The decrease in GH concentration was more significant after pasireotide administration compared to octreotide administration (P<0.001). The median decrease in GH concentration in octreotide test was 1.255 μg/l (IQR: 0.918–1.75) vs 2.805 μg/l (IQR: 1.523–5.043) after pasireotide administration. Octreotide was generally better tolerated than pasireotide.

Short-acting pasireotide is more effective than short-acting octreotide in GH supression in patients with uncontrolled acromegaly. Pasireotide may be a promising alternative for patients resistant to first-generation somatostatin analogs.