Study to Determine the Pharmacokinetics and Pharmacodynamic Effects of Phenylephrine on BP Via IV

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.

Inclusion criteria

• Subject's age is between ≥12 and 16 years, inclusive
• Subject is scheduled for a procedure that requires general or neuraxial anesthesia
• Subjects must have normal or clinically acceptable physical exam
• Subjects with controlled diabetes prior to entry must have a mean systolic/diastolic office blood pressure ≤128/78 mmHg (sitting, after 5 minutes of rest)
• Females must have a urine or serum pregnancy test (Human Chorionic Gonadotropin) that is negative at Screening and Day 1
• Subject's parent or legal guardian gives informed consent and subject gives assent.

Exclusion criteria

• Subject has a contraindication to vasoconstrictor therapy for control of blood pressure
• Subject has participated in other clinical trials for investigational drugs and/or devices within 30 days prior to enrollment
• Subject has any serious medical condition which, in the opinion of the investigator, is likely to interfere with study procedures
• Subjects who have a history of any clinically significant local or systemic infectious disease within four weeks prior to initial treatment administration
• Subjects who are positive for hepatitis B surface antigen or hepatitis C antibody
• Subjects taking antihypertensive medication
• Subject is moribund (death is likely to occur in less than 48 hours)
• Females who are pregnant, nursing or unwilling to use/practice adequate contraception.