Stress stability study of simeprevir, a hepatitis C virus inhibitor, using feasible TLC-spectro-densitometry: application to pharmaceutical dosage form and human plasma

Application of different spectrophotometric methods for quantitative analysis of direct acting antiviral drugs simeprevir and sofosbuvir

Simeprevir and sofosbuvir are direct-acting antiviral drugs approved for the treatment of chronic HCV infection. Reports demonstrate the similarities between HCV and SARS-CoV-2 in terms of structure and replication mechanism. Therefore, it is suggested that a combination of simeprevir and sofosbuvir may be considered for COVID-19 patients. To date, no spectrophotometric methods have been published for quantitative analysis of simeprevir and sofosbuvir in combination. In this work, two simple spectrophotometric methods allowed quantitative analysis of the studied drugs in the mixed form. The zero-order direct method allowed quantitative analysis of simeprevir at 333 nm, with sofosbuvir showing zero absorbance values. The dual wavelength method allowed quantitative analysis of sofosbuvir by measuring the difference in absorbance values at 259.40 and 276 nm, where the difference in absorbance values of simeprevir was zero. With the applied methods, the investigated drugs in the mixtures and tablets prepared in the laboratory were successfully analyzed quantitatively with acceptable results.

Identification, isolation, structural characterization, in silico toxicity prediction and in vitro cytotoxicity assay of simeprevir acidic and oxidative degradation products

Simeprevir is a new direct-acting antiviral drug used for the treatment of chronic hepatitis C. In this work, a simple, fast and economical chromatographic method was developed for the determination of simeprevir in the presence of its acidic and oxidative degradation products. The stress studies performed herein showed that simeprevir degraded under acidic and oxidative conditions but was stable under thermal and alkaline conditions. Chromatographic separation was achieved on a reversed-phase Eclipse XDB C₁₈ column (4.6 × 150 mm, 5 μm). The mobile phase consisted of methanol-0.05 M ammonium acetate (pH 4) (90 : 10, v/v) and was used at a flow rate of 1 mL min⁻¹. The column effluent was monitored at 237 nm. The calibration curve was linear over the concentration range of 0.1–20 μg mL⁻¹. The relative standard deviations for the intra-day and inter-day precision were less than 2%, and good percentage recoveries that met the acceptance criteria of the International Conference on Harmonization (ICH) guidelines were obtained. The robustness was assessed using the Plackett–Burman design. The simeprevir degradation products were isolated by flash chromatography and confirmed by ¹H NMR and LC-MS/MS techniques. The fully validated chromatographic method can be applied as a stability-indicating method for simeprevir and for routine analysis during quality control. Additionally, in silico toxicity prediction of the degradation products demonstrated a hepatotoxicity alert for DP 1, DP 2, DP 4 and DP 5 and a carcinogenicity alert for DP 3. In view of safety aspects, an in vitro cytotoxicity assay was carried out for simeprevir degradation products. They were found to be non-toxic in vitro at the tested concentrations.

Simeprevir is a new direct-acting antiviral drug used for the treatment of chronic hepatitis C.