Effect of Octreotide, a Somatostatin Analog, on Sleep Apnea in Patients with Acromegaly

OBJECTIVE: To determine the effects of octreotide, a somatostatin analog, on the severity of sleep apnea and on growth hormone levels in patients with acromegaly. DESIGN: Open-label, prospective study. SETTING: Tertiary referral hospital. PATIENTS: 19 patients with active acromegaly. INTERVENTION: Octreotide in a 6-month, stepwise incremental dosage. MEASUREMENTS: Sleep studies and indices of hormonal activity (levels of insulin-like growth factor 1 [IGF-1] and growth hormone). RESULTS: A 50% decrease occurred in the respiratory disturbance index (baseline compared with 6 months, 39 events/h compared with 19 events/h; P = 0.0002), and a 40% decrease occurred in total apnea time (27.6% of total sleep time compared with 15.1%; P = 0.001). Indices of oxygen desaturation, sleep quality, and subjective sleepiness improved after 6 months of octreotide. A parallel decrease was noted in mean levels of growth hormone (40.0 micrograms/L compared with 9.1 micrograms/L; P = 0.003) and IGF-1 (107 nmol/L compared with 47 nmol/L; P = 0.0001). However, no correlation was noted between the decrease in the total amount of sleep time spent in apnea and the decrease in growth hormone levels (rho = -0.35; P > 0.2). The residual respiratory disturbance index after 6 months of treatment was similar in patients who improved, regardless of whether or not biochemical remission (IGF-1 < 35 nmol/L) occurred. CONCLUSIONS: Improvement in indices of sleep apnea severity occurs in association with octreotide treatment in patients with sleep apnea and acromegaly. However, sleep apnea may either persist despite normalization of growth hormone levels or may improve markedly even if there is only partial biochemical remission.