Octreotide Dose Escalation as Pr Octreotide Dose Escalation as Primary and Secondary Therapy for Patients with Acromegaly A Clinical Study Abbas Mahdi Rahmah* FRCP, Nizar Shawky Shawky CABM, Noor Thair Tahir* PhD

Abstract

Background: Acromegaly is known to reduce life expectancy. Predictors of survival are growth hormone (GH)  2.5 µg/L and normal insulin like growth factor-1. Objective: To evaluate efficacy of dose escalation of octreotide – long – acting – repeatable from 20 to 40 mg every 28 days intramuscularly in a sample of acromegalic patients whose biomarkers fail to drop down to the recommended targets after using octreotide – long – acting – repeatable for a year (20 mg) every 28 days.

Methods: An analytic, observational, open and prospective study. Seventeen acromegalic patients using octreotide – long – acting – repeatable 20 mg every 28 days fail to reduce growth hormone < 2.5 µg/L and insulin like growth factor-1 to the recommended level. The dose was doubled for six months, in order to achieve the recommended goals of growth hormone and insulin like growth factor-1. The patients were divided into two groups in each occasion: - Those harbouring microadenoma versus macroadenoma. - Patients with previous hypophysectomy versus those with no prior hypophysectomy. - Males versus females. - Those with a disease duration ≥ 10 years versus those with a disease duration of < 10 years. - Sonogram of the abdomen and oral glucose tolerance test were done prior to recruitment and at the end of the study.

Results: Growth hormone and insulin like growth factor-1 levels drop by 62.5% and 37%, respectively, on 40 mg monthly octreotide – long – acting – repeatable in those who underwent hypophysectomy and by 63.5% and 38%, respectively, in those with no history of hypophysectomy. Those two biomarkers drop by 61.4% and 35.3% in those harboring macroadenoma and by 70% and 42% in those harboring microadenoma. The decrement of growth hormone, and insulin like growth factor-1 was found to be 70% and 41.9%, respectively, in those with disease duration ≥ 10 years and by 66.9% and 34.8% in those with disease duration < 10 years. In males these biomarkers drop by 63% and 38% while in females, they drop by 59% and 31%, 6 months after doubling the dose of octreotide – long – acting – repeatable. No patient developed impairment of glucose tolerance or gall stones at the end of study period.

Conclusion: Increasing the dose of octreotide – long – acting – repeatable from 20 to 40 mg every 28 days in acromegalic patients, resistant to the conventional dose of octreotide – long – acting – repeatable is found to be fruitful in reducing growth hormone and insulin like growth factor-1 by significant percentage irrespective of gender, disease duration, previous hypophysectomy or harboring micro or macro adenoma.