FOLFOX is the most common chemotherapy combination prescribed in colorectal cancer. It is composed of calcium levofolinate, 5-fluorouracil and oxaliplatin which demonstrated synergistic outcome. Nowadays, the lack of all-in-one formulation is due to the chemical composition of the pharmaceutical products and the highly pH-dependent stability of each drug. Herein, we aimed to investigate the stability of a ternary mixture of 5-fluorouracil, oxaliplatin and calcium levofolinate, knowing that coadministering these drugs would improve their efficacy. The effect of three pHs (5.0, 6.0 and 7.5) and two drug concentrations (8/3/6 and 1/1/1 mg/ml for 5-fluorouracil, oxaliplatin and calcium levofolinate, respectively) were examined. A high-performance liquid chromatography method was developed to separate and quantify the three drugs in one run. At higher concentrations, the ternary mixture was unstable regardless of pH. By reducing concentration, drug stability and compatibility in the mixture was improved at pH 5.0 for up to 3 days at +5°C ± 3 °C. In addition, binary mixtures provided stable properties at defined pHs. 5-fluorouracil/oxaliplatin mixture was stable at pH 5.0 over 48 hours while 5-fluorouracil/calcium levofolinate mixture was stable at pHs 6.0 and 7.5 up to 7 days.
Keywords: 5-Fluorouracil; calcium levofolinate; drug mixtures stability; oxaliplatin; pH effect.