Patent ID: 7566462

Claim:
A stable tablet formulation comprising an initial amount of a crystalline polymorph, designated polymorph B, of (6R)-L-erythro-tetrahydrobiopterin dihydrochloride, an antioxidant, and a pharmaceutically acceptable excipient, diluent, or carrier in the form of a tablet, wherein the weight ratio of the antioxidant to the (6R)-L-erythro-tetrahydrobiopterin dihydrochloride is about 1:5 to about 1:30; wherein after six months in a container at room temperature and about 60% humidity the stable tablet formulation retains at least about 95% of the initial amount of (6R)-L-erythro-tetrahydrobiopterin dihydrochloride, and wherein said crystalline polymorph B exhibits an X-ray powder diffraction pattern with the following characteristic peaks expressed in d-values (Å): 8.7 (vs), 5.63 (m), 4.76 (m), 4.40 (m), 4.00 (s), 3.23 (s), and 3.11 (vs).