Selepressin, a novel selective vasopressin V1A agonist, is an effective substitute for norepinephrine in a phase IIa randomized, placebo-controlled trial in septic shock patients

James A. Russell, Jean-Louis Vincent, Anne Louise Kjølbye, Håkan Olsson, Allan Blemings, Herbert Spapen, Peder Carl, Pierre-Francois Laterre, Lars Grundemar

Vasopressin is widely used for vasopressor support in septic shock patients, but experimental evidence suggests that selective V1A agonists are superior. The initial pharmacodynamic effects, pharmacokinetics, and safety of selepressin, a novel V1A-selective vasopressin analogue, was examined in a phase IIa trial in septic shock patients. This was a randomized, double-blind, placebo-controlled multicenter trial in 53 patients in early septic shock (aged ≥18 years, fluid resuscitation, requiring vasopressor support) who received selepressin 1.25 ng/kg/minute (n = 10), 2.5 ng/kg/minute (n = 19), 3.75 ng/kg/minute (n = 2), or placebo (n = 21) until shock resolution or a maximum of 7 days. If mean arterial pressure (MAP) ≥65 mmHg was not maintained, open-label norepinephrine was added. Co-primary endpoints were maintenance of MAP >60 mmHg without norepinephrine, norepinephrine dose, and proportion of patients maintaining MAP >60 mmHg with or without norepinephrine over 7 days. Secondary endpoints included cumulative fluid balance, organ dysfunction, pharmacokinetics, and safety. A higher proportion of the patients receiving 2.5 ng/kg/minute selepressin maintained MAP >60 mmHg without norepinephrine (about 50% and 70% at 12 and 24 h, respectively) vs. 1.25 ng/kg/minute selepressin and placebo (p < 0.01). The 7-day cumulative doses of norepinephrine were 761, 659, and 249 μg/kg (placebo 1.25 ng/kg/minute and 2.5 ng/kg/minute, respectively; 2.5 ng/kg/minute vs. placebo; p < 0.01). Norepinephrine infusion was weaned more rapidly in selepressin 2.5 ng/kg/minute vs. placebo (0.04 vs. 0.18 μg/kg/minute at 24 h, p < 0.001), successfully maintaining target MAP and reducing norepinephrine dose vs. placebo (first 24 h, p < 0.001). Cumulative net fluid balance was lower from day 5 onward in the selepressin 2.5 ng/kg/minute group vs. placebo (p < 0.05). The selepressin 2.5 ng/kg/minute group had a greater proportion of days alive and free of ventilation vs. placebo (p < 0.02). Selepressin (2.5 ng/kg/minute) was well tolerated, with a similar frequency of treatment-emergent adverse events for selepressin 2.5 ng/kg/minute and placebo. Two patients were infused at 3.75 ng/kg/minute, one of whom had the study drug infusion discontinued for possible safety reasons, with subsequent discontinuation of this dose group. In septic shock patients, selepressin 2.5 ng/kg/minute was able to rapidly replace norepinephrine while maintaining adequate MAP, and it may improve fluid balance and shorten the time of mechanical ventilation. ClinicalTrials.gov, NCT01000649 . Registered on September 30, 2009.