Optimal dosage interval for depot somatostatin analogue therapy in acromegaly requires individual titration

BACKGROUND The recent introduction of the depot somatostatin analogues octr eotide LAR and lanreotide represent major advances in the medical treatment of acromegaly, However, it Is uncertain whether the recommended dose inter vals of 4 weeks and 10-14 days, respectively, are applicable to all patient s. AlMS To determine the optimum intervals between depot injections of either octreotide LAR and lanreotide for the suppression of serum GH and IGF-I in patients with acromegaly, METHODS Twenty-seven patients with acromegaly were randomly allocated to re ceive either three injections at 4 week intervals of octreotide LAR (n = 18 ) or five injections at 14 day intervals of lanreotide (n = 11); two patien ts participated in both arms, Prior to the first injection, at 4 and 6 week s after the last injection of LAR, and at 10, 14 and 21 days after the last injection of lanreotide, serum mean GH and IGF-I levels were measured, RESULTS In the LAP-treated group, at 4 and 6 weeks after the third Injectio n 13 patients (72%) and 12 patients (67%), respectively, had a mean GH < 5 mU/I. IGf-I was normalized in 12 and 11 patients at these times. In the lan reotide-treated group, five (45%), four (36%) and three (27%) patients, res pectively, had a GH < 5 mU/I at 10, 14 and 21 days after the last injection and eight, six and five patients had a normal serum IGF-I, CONCLUSIONS There is marked variability in individual patient responses to depot somatostatin analogues. The establishment of optimal drug Intervals r equires careful assessment. For octreotide LAR many patients may be as adeq uately controlled with 6 weekly injections as with 4 weekly injections. It is important to measure serum GH profiles at intervals after initiating the rapy with these drugs to individualize doses for each patient and hence min imize cost.