Preclinical evaluation of novel, all-in-one formulations of 5-fluorouracil and folinic acid with reduced toxicity profiles

5-Fluorouracil (5-FU) in combination with its synergistic biomodulator folinic acid maintains a pivotal position in cancer chemotherapy. However, clinical limitations such as phlebitis and catheter blockages persist with the administration of these drugs in combination, and are associated with reduced efficacy and/or quality of life for patients. We have reported earlier on the novel, all-in-one, pH neutral, parenteral 5-FU and folinic acid formulations (termed Fluorodex) incorporating β-cyclodextrins. Fluorodex maintains potency while overcoming the accepted incompatibility of 5-FU and folinic acid. We carried out toxicological, pharmacokinetic and biodistribution, and efficacy evaluations of Fluorodex compared with 5-FU:folinic acid using several administration routes and schedules in two rodent models. These were compared with the dose-matched sequential administration of 5-FU:folinic acid. Fluorodex showed bioequivalence to 5-FU:folinic acid as assessed by the tissue distribution and pharmacokinetic studies of 5-FU, but was generally better tolerated as determined by weight loss, hematological, and other clinical parameters. Compared with 5-FU:folinic acid, Fluorodex was also associated with reduced phlebitis using a rabbit ear vein model. Furthermore, using human carcinoma tumor models in mice, Fluorodex resulted in equivalent or improved efficacy profiles compared with 5-FU:folinic acid. In conclusion, these novel, all-in-one formulations represent a superior injectable form of 5-FU that allows codelivery of folinic acid. This should translate into improved patient tolerability with potential for enhanced efficacy.