This is a Phase 4 multi-center, randomized open-label study in 100 subjects aged ≥12 to 16 years who experience a decrease in blood pressure during a procedure requiring general or neuraxial anesthesia. At least 300 subjects will be enrolled in this study. It is anticipated that up to 33% of enrolled subjects will actually experience a decrease in blood pressure that requires treatment and so will receive Phenylephrine Hydrochloride Injection (PHI). There are 12 possible randomization assignments: one of six initial treatments PHI will be initially administered to approximately 50 subjects as an intravenous bolus (IV-B) at Low (1 μg/kg), Med (3 μg/kg), or High (5 μg/kg) level; PHI will be initially administered to approximately 50 subjects as a continuous intravenous infusion (IV-I) at Low (0.25 μg/kg/min), Med (0.75 μg/kg/min), or High (1.25 μg/kg/min) level\]; each initial treatment group will have two pharmacokinetics (PK) sampling schedules.
