Systematic dose-extension of octreotide LAR: the importance of individual tailoring of treatment in patients with acromegaly.

Abstract

The depot long-acting somatostatin analogue octreotide LAR (LAR) provides effective and well-tolerated treatment for acromegaly. Despite a 4-weekly recommended injection frequency, prolonged duration of GH suppression has been observed in some patients following treatment with long-acting somatostatin analogues. The aim of our study was to perform a prospective systematic study to determine whether extending the interval between doses of LAR allows maintenance of 'safe' GH in selected patients with acromegaly. Twenty-two patients (15 men, seven women), mean age 58.9 years (35-81 years) with active acromegaly (mGH > 5 mU/l), requiring treatment were selected to receive treatment with LAR. Eleven patients had received previous treatment with both transsphenoidal surgery and radiotherapy, while six had received surgery alone. All patients were commenced on treatment with 20 mg LAR intramuscularly (i.m.) every 4 weeks. Mean GH (mGH) was measured after three consecutive injections immediately prior to the fourth injection. The dose frequency was systematically reduced after every four injections if mGH < 5 mU/l. Once mGH > 5 mU/l, the dose frequency was increased and mGH reassessed. The dosing interval was successfully increased to greater than 4 weeks in 20/22 patients (90.9%). Six of 22 (27.3%) were receiving injections every 8 weeks and 3/22 (13.6%) every 12 weeks. GH and IGF-I were lower on treatment compared with baseline (P < 0.01). There was no difference in individual mGH and IGF-I between the values on 4-weekly dosing and those at final dose frequency. There was no relationship between final dose frequency and either mean GH or IGF-I prior to LAR, patient age, or previous treatment. The percentage suppression following 100 micro g octreotide subcutaneously did not predict subsequent dose frequency of LAR. The drug cost if patients had continued at 4-weekly intervals would be UK pound 187 850, compared with UK pound 101 065 for the individually titrated dose frequency (P < 0.01). This represents a final cost of 53.8% of the 4-weekly injection price. Individual tailoring of LAR administration maintains control of acromegaly, with reduced injection frequency and improved cost-effectiveness.