Effects of different octreotide dosages on splanchnic hemodynamics and glucagon in healthy volunteers

Aims: This study evaluated the dependence of po rta I a nd mesenteric blood flow and plasma glucagon levels on octreotide dosage and its mode of application. Methods: Two groups of 10 individuals each received octreotide either subcutaneously (placebo, 100 and 200 mu g) or intravenously(100-mu g bolus i.v., 25 and 100 mu g/h) in a double-blind, random order. Using Doppler ultrasound, we examined portal and mesenteric blood flow and measured plasma glucagon levels at regular intervals within a 4-hour period under fasting conditions. Results: Contrary to placebo, octreotide caused a decrease in portal blood flow (PVF) and in superior mesenteric artery blood flow (SMAF) together with an increase in the mesenteric pulsatility index (PI). The same total dose of 100 mu g octreotide caused a similar PVF response, averaged over 4 h, given either subcutaneously (-28.0 +/- 4.8%), intravenously (-29.4 +/- 4.3%) or as a continuous infusion (-29.3 +/- 4.6%). As concerns intravenous infusions, 100 mu g/h was more effective than 25 mu g/h (-37.8 +/- 6.2 vs. -29.3 +/- 4.6%). The PVF reduction remained constant during intravenous infusion, whereas glucagon levels decreased progressively over the entire observation time. Conclusions: The decrease in PVF is dependent on the octreotide dose. However, this is not constantly paralleled by a decrease in plasma glucagon concentration.