IMPROVED BIOAVAILABILITY OF PARA-BORONOPHENYLALANINE BY CYCLODEXTRIN COMPLEXATION

This study was undertaken to develop an oral dosage form for para-boro nophenylalanine (BPA) plus cyclodextrin (CD) for use in the thermal ne utron capture therapy for malignant melanoma. Powders of the BPA and C D complexes were obtained in a molar ratio of 1:2. X-ray diffraction o f the BPA-CD complexes showed halo patterns that indicated that each c omplex was in a new solid state as an amorphous compound. The enhancem ent of BPA solubility by glucosyl (G1)- and maltosyl (G2)-alpha-CD was greater than that with the other CDs. The isolation rate of BPA from its complex was different for each BPA-CD complex. The bioavailability of BPA in rats was improved with oral administration of the BPA-alpha -CD, G1-alpha-CD, and G2-alpha-CD complexes. In contrast, a complex of BPA and dimaltosyl (G2G2) or G2-beta-CD, which had low release rate a nd low solubility, did not improve the bioavailability of BPA. These r esults indicate that the solubility and release rate of BPA from a com plex in solution are important for the bioavailability of BPA after or al administration of BPA-CD complexes.