A Pharmacokinetics (Blood Levels), Pharmacodynamics (How the Drug Acts on the Body) and Safety Study Dosing of Rabeprazole in New Borns With Gastroesophageal Reflux Disease (GERD).

This is an multi-center Phase I study in new borns and pre-term infants (less than 44 weeks
at the time of the first dose). The drug being studied is rabeprazole sodium, the active
pharmaceutical ingredient in AcipHex. This study will consist of two parts, Part 1 and Part
2. Each part will consist of three phases, a pre-treatment phase (screening of up to 7 days
before the start of treatment), a treatment phase (up to 28 days) and a post treatment phase
(at least 14 days, but no more than 21 days after the last dose of study drug). The maximum
study length for each patient will therefore be up to 8 weeks. Patients will be monitored
patients with a presumptive diagnosis of GERD and who need a feeding tube for enteral
alimentation (complete or partial) in place and have been admitted to a newborn intensive
care unit or step down unit. The population blood level (pharmacokinetics) results,
together with the safety and tolerability data, from Part 1 will be assessed to determine
the two dose levels to be studied in Part 2 before the start of dosing. All 14 patients in
Part 1 will require pH monitoring for clinical management and undergo a 24-hour PD
assessment (intraesophageal and intragastric pHmetry). At least 6 patients in Part 2 (3
patients from each dose group) will require pH monitoring and undergo the same
pharmacodynamics assessment as patients in Part 1. Patients participating in the pHmetry
assessment must be in need of this assessment for their clinical management in the opinion
of the Principal Investigator. The intraesophageal and intragastric 24-hour pH
pharmacodynamics assessment in both Part 1 and Part 2 will be performed at baseline (Day -1)
and after the first dose (Day 1) and fifth dose (Day 5). Sampling for single dose blood
level (Pharmacokinetic) evaluations will be performed post-dose on Day 1. Sampling blood
level evaluations at the presumed steady-state during multiple dosing will be performed on
Day 5. Patients' safety will be monitored throughout the study. At the end of the study, or
if any patient prematurely discontinues his/her participation in the study, a safety
evaluation will be performed at least 14 days, but no more than 21 days, after the final
rabeprazole sodium dose. During the course of the study, after consent each patient will
have medical history, a physical, length, weight, vital signs, blood chemistry, and
urinanalysis. Safety from baseline to the End of Study visit (post-treatment phase) will be
evaluated by examining incidence, severity and relationship to the study drug and type of
Adverse Events (AEs), urinalysis, physical examination and vital signs. Patients will
receive rabeprazole sodium as a single daily dose for up to 28 consecutive days. Patients
participating in Part 1 will receive 1.0 mg rabeprazole sodium administered by a nasogastric
tube. After four patients complete Part 1, their rabeprazole plasma levels will be assess
and may be increased to 2.0 mg rabeprazole sodium. The population pharmacokinetics results,
safety and tolerability data from Part 1 will be assessed to determine 2 doses in Part 2.