Abstract
Onconova 1210.Na (1210) is a chlorobenzylsulfone derivative with potential property to mitigate the effects of accidental or intentional exposure to life threatening levels of radiation. A rapid and sensitive HPLC method was developed and validated for the determination of 1210. An isocratic system using a C-18 Gemini column (250 x 4.6 mm) with column effluents monitored at 254 nm was used. The mobile phase comprised of acetonitrile:0.1% trifluroacetic acid in water (60:40, v:v) at a flow rate of 1 ml/min. The assay validation parameters evaluated include specificity, linearity, precision, accuracy and sensitivity. The retention time of the drug and the other effluents were well within seven minutes. Standard curves were linear over the concentration range of 10-500 [Ag/ml. The RSD values for the within-day and day-to-day precision ranged from 0.4 to 2.5 % and 2.2 to 4.4 %, respectively. The RSD for accuracy measurement ranged from 0.85 to 1.7 %. The critical level, the detection level, and the determination level for this assay were 2.86 ± 0.67 fig/ml, 5.69 ± 0.67 fig/ml and 15.6 ± 1.79 [xg/ml. Forced degradation of the drug was achieved by autoclaving 1210 with HCl (0.05N), NaOH (0.05 N) or hydrogen peroxide(1.5% v/v). Preformulation studies included determination of microscopic and macroscopic properties, partition coefficient, pKa, pH-dependant solubility, pH-dependant stability, solid-state characterization and solid-state stability. XRD (X ray diffraction) and Thermal analyses were used to characterize the solid and solid-state stability. Microscopic and XRD data revealed that the drug was crystalline with an irregular plate like structure. 1210 has a low octanol : water partition coefficient (1.3-2.9) and low aqueous solubility. The equilibrium solubility data shows that solubility of the drug was dependent upon the solvent used. The pKa determined from pH solubility study was 2.85 ± 0.6. The pH-stability profile of the drug indicated increased stability at neutral and biological pH but degradation was rapid under acidic condition. The degradation of drug in solution followed a first-order rate and was pH dependant. The accelerated solid-state stability studies of the bulk drug substance by HPLC showed no evidence of degradation. In conclusion, a simple, sensitive, and stability indicating HPLC assay was developed and validated for the analysis of a novel radioprotectant. This drug was quite stable both in an aqueous environment at biological pH, and in the solid state. Therefore, it can be formulated as a shelf stable parenteral formulation. The aqueous solubility of the drug is low and can be enhanced by increasing the pH, by using cosolvent systems, and by complexation agents like cyclodextran. A suspension formulation was developed using 0.1M Potassium phosphate monobasic, 1% Tween 80 and 0.15M sodium chloride. The stability data of the drug indicates that there is less than 50% degradation in both solution and suspension phase.