Background Sodium dichloroacetate (Na-DCA), not a patented substance, which is used in the treatment of rare diseases with congenital defects of the pyruvate-dehydrogenase complex (PDHC), produces a marked reduction in acid-base imbalance and lactic acid levels toxic to the brain parenchyma.
Purpose To evaluate the physical-chemical stability of sodium dichloroacetate in aqueous solution.
Materials and Methods Six grammes of sodium dichloroacetate were dissolved in 60 ml of water for injections (WFI). The exact concentration of the solution obtained was calculated by extrapolation from a calibration curve, recording the absorbance value at the wavelength of 198 nm of suitable standard solutions (5–50 µg/ml) of sodium dichloroacetate dissolved in water for injections (WFI). The solution was divided between 3 dark glass containers. The first container was kept at room temperature (r.t.), the second one in a refrigerator at +4°C, the third one in a freezer at −20°C. The stability of the samples, kept at different temperatures, was checked at 31, 45, 54 and 60 days; for each sample, using appropriate dilution, absorbance values were recorded (λ = 198 nm) and through the sodium dichloroacetate calibration curve made daily, the concentrations of the substance being analysed were calculated. The results were expressed as percentages of sodium dichloroacetate in solution.
Results Samples kept at +4°C were stable throughout the observation period. Samples kept at r.t. were stable until 30 days from preparation, while afterwards a slow and gradual decay could be observed. Samples kept at −20°C showed a progressive increase in concentration.
Conclusions The observed increase in samples at −20°C can be explained by the formation of a secondary species with a higher extinction coefficient than sodium dichloroacetate. Data suggest that sodium dichloroacetate solutions should not be stored at −20°C or at r.t. for more than 30 days.
No conflict of interest.
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