Population Pharmacokinetic Analysis of Lanreotide Autogel® in Healthy Subjects

Lanreotide is a somatostatin analogue used for the treatment of acromegaly and neuroendocrine tumours. The objective of this study was to develop a pharmacokinetic model for the sustainedrelease formulation lanreotide Autogel® after deep subcutaneous administration in healthy subjects, and to explore the potential effect of covariates, especially sex and dose.

This was an open-label, single-centre, randomized, dose-ranging, parallel-group study, with a follow-up period of 4–7 months following drug administration in healthy subjects. Healthy Caucasian subjects aged 18–45 years were included. Subjects received a rapid intravenous bolus of 7 μg/kg of an immediate-release formulation of lanreotide (lanreotide IRF). After a 3-day washout period, participants were randomized to receive a single deep subcutaneous injection of lanreotide Autogel® at a dose of 60, 90 or 120 mg.

Blood samples for lanreotide determination were obtained during the first 12 hours after the intravenous bolus injection and during the 4- to 7-month follow-up period after deep subcutaneous administration of lanreotide Autogel®. Data after intravenous and subcutaneous administration were fitted simultaneously using the population approach in NONMEM® version VI software. The model was validated externally using data from patients with acromegaly.

In total, 50 healthy subjects (24 women and 26 men) received a single intravenous dose of lanreotide IRF. Of these, 38 subjects (18 women and 20 men) received a single subcutaneous dose of lanreotide Autogel® 3 days after intravenous lanreotide IRF. The disposition of lanreotide was described by a three-compartment open model. The estimates of the total volume of distribution and serum clearance were 15.1 L and 23.1 L/h, respectively. The estimates of interindividual variability were <40%. To evaluate lanreotide Autogel® pharmacokinetics, the absorption rate was modelled to decrease exponentially as a function of the natural logarithm of time. The absolute bioavailability after deep subcutaneous administration of lanreotide Autogel® was 63%. The rate of absorption and bioavailability of lanreotide Autogel® were independent of the administered dose in the range from 60 to 120 mg, and no significant effect of covariates (sex, dose, age or bodyweight) was found (p > 0.05).

Population analysis allows a full description of the disposition of lanreotide after rapid intravenous bolus administration of lanreotide IRF (7 μg/kg) and the pharmacokinetics of lanreotide Autogel® after a single deep subcutaneous injection (60, 90 or 120 mg) in healthy subjects. The model-based simulations provide support for the feasibility of extending the dosing interval for lanreotide Autogel® to 56 days when given at 120 mg. The absorption profile of lanreotide Autogel® was independent of the dose and was not affected by sex.