A Phase 2, Pharmacokinetic (PK) Study of 6R-BH4 Alone or 6R-BH4 With Vitamin C in Subjects With Endothelial Dysfunction

This was a Phase 2, randomized, open-label, 2-treatment, 2-sequence, 2-period crossover, pharmacokinetic (PK) study designed to compare the plasma concentrations of BH4 in subjects with endothelial dysfunction following 14 days of treatment by each of 2 regimens: sapropterin dihydrochloride with vitamin C and sapropterin dihydrochloride alone. Each subject received each regimen; the 2 treatment groups varied only in the sequence of the 2 regimens. The washout period between treatment regimens comprised the 1 day period between the last dose of study drug under the first regimen and the first dose of study drug under the second regimen (Day 14 morning to Day 15 morning).