Febuxostat (FBX), a selective xanthine oxidase inhibitor, belongs to BCS class II showing low solubility and high permeability with a moderate F value (< 49%). Recently, FBX/L-pyroglutamic acid cocrystal (FBX-PG) was developed with improving 4-fold increase of the FBX solubility. Nevertheless, in vivo pharmacokinetic property of FBX-PG has not been evaluated yet. Therefore, the pharmacokinetic feasibility of FBX in FBX and FBX-PG-treated rats and mice was compared in this study. The results showed that the F values of FBX were 210% and 159% in FBX-PG rats and mice, respectively. The 2.10-fold greater AUC of FBX was due to the increased absorption (i.e., 2.60-fold higher Cmax,1 at 15 min) and entero-hepatic circulation of FBX (i.e., 1.68-fold higher Cmax,2 at 600 min) in FBX-PG rats compared to the FBX rats. The 1.59-fold greater AUC of FBX was due to a 1.65-fold higher Cmax,1 at 5 min, and 1.15-fold higher Cmax,2 at 720 min of FBX in FBX-PG mice than those in FBX mice. FBX was highly distributed in the liver, stomach, small intestine, and lungs in both groups of mice, and the FBX distributions to the liver and lungs were increased in FBX-PG mice compared to FBX mice. The results suggest the FBX-PG has a suitable pharmacokinetic profile of FBX for improving its oral F value.

The CAALA (Complex Augmentation of ALA) regimen was developed with the goal of redressing some of the weaknesses of 5-aminolevulinic acid (5-ALA) use in glioblastoma treatment as it now stands. 5-ALA is approved for use prior to glioblastoma surgery to better demarcate tumor from brain tissue. 5-ALA is also used in intraoperative photodynamic treatment of glioblastoma by virtue of uptake of 5-ALA and its selective conversion to protoporphyrin IX in glioblastoma cells. Protoporphyrin IX becomes cytotoxic after exposure to 410 nm or 635 nm light. CAALA uses four currently marketed drugs - the antibiotic ciprofloxacin, the iron chelator deferiprone, the antimetabolite 5-FU, and the xanthine oxidase inhibitor febuxostat - that all have evidence of ability to both increase 5-ALA mediated intraoperative glioblastoma demarcation and photodynamic cytotoxicity of in situ glioblastoma cells. Data from testing the full CAALA on living minipigs xenotransplanted with human glioblastoma cells will determine safety and potential for benefit in advancing CAALA to a clinical trial.