7483 The Pharmacokinetic Profile of Lanreotide Autogel® Improved Long-Term Arrhythmia Fluctuations in Acromegalic Cardiomyopathy

Abstract Disclosure: M. Iwabuchi: None. Background: The prognosis of acromegaly is related to the status of cardiac complications. Ventricular premature contractions (VPC) are frequently observed in acromegaly, and it is very important to suppress fatal arrhythmias to improve long-term prognosis. Somatostatin analogs are widely used as pharmacotherapy for acromegaly, and they have been reported to improve cardiac prognosis. In comparison to LAR, lanreotide Autogel® has a unique property of self-aggregation under favorable conditions, leading to a stable structure of highly organized nanotubules and has a long half-life after subcutaneous injection determined by pseudo-first order kinetics. CASE: 55-year-old man visited a cardiologist for the treatment of PVCs and heart failure. Because of his acromegalic features, endocrinological and image examinations were performed, and diagnosis of acromegaly was confirmed. His GH was 7.17 ng/mL, IGF-1 566 ng/mL (Normal range: 59-215). Concerning excess of GH may cause nonischemic cardiomyopathy, administration of 20 mg of LAR once a month was started. GH and IGF-1 improved to1.52 ng/mL and 217 ng/mL respectively. The dose of LAR was increased to 30mg because of a remaining fluctuation of VPCs. Considering a possibility of the problem of bioavailability due to method of injection and the pharmacokinetics of LAR, administration of lanreotide Autogel® was started instead of LAR, with the result that an improvement of the fluctuation of the symptom was observed without remarkable change in GH and IGF-1. Arrhythmia status was assessed over time using Holter electrocardiography. Pretreatment Holter electrocardiogram showed 18% of total heart rates in PVCs. After LAR injection, the frequency of PVCs decreased to 3%, and 6 years after changing LAR to lanreotide, the frequency of PVCs decreased to 2%. Clinical Lessons: Simulated steady state pharmacokinetic profiles of LAR and lanreotide Autogel® differ significantly. During LAR treatment, serum concentrations of the drug are approximately stable, whereas the characteristic first-order kinetics of lanreotide Autogel® is superimposed on levels just before the next administration. The pharmacokinetic differences indicate that LAR can be better tailored to therapeutic levels, whereas serum levels of lanreotide must be high for part of the interval between injections to be effective in the period before the next administration. Lanreotide Autogel® has similar clinical effects compared to LAR for the treatment of cardiomyopathy of acromegaly and has the advantage of being available in a convenient pre-filled syringe and no necessity of injection by healthcare professionals. It is suggested that the pharmacokinetic profile of Lanreotide Autogel® resulted in decreased arrhythmia fluctuation in acromegalic hearts, which has been maintained for the past 6 years. Presentation: 6/3/2024