Development and Validation of a UHPLC UV Method for the In-Process Control of Bosentan Monohydrate Synthesis

Simple Determination of Bosentan in Plasma Samples by Reversed-Phase High-Performance Liquid Chromatography

Background

In order to measure the plasma levels of Losartan and Bosentan, a sensitive Reverse Phase-High Performance Liquid Chromatography (RP-HPLC) technique was developed.

Methods

To compare bioavailability, the Area Under the Curve (AUC), peak plasma concentration (Cmax), and time to Cmax (Tmax) were employed. The standard curve (150-2400 ng/ml) was linear (R2=0.999), relative errors were between 2.4 to 10.05% and the coefficient of variation (CV%) ranged from 1.52 to 10.88. A single dosage (test and reference) was used for the in vivo investigation, which involved 16 healthy individuals.

Results

The AUC0-48, AUC0-, Cmax, and Tmax of the test and reference had no statistically significant differences. The Cmax and 95% confidence intervals of the ratio of Cmax of the two formulations were 0.93-0.96 and 97.6-135%, respectively.

Conclusion

Therefore, it was established that generic Bosentan was equivalent to Bosentan from Actelion and that both medications could be regarded as equally effective in clinical settings. The blood level of Bosentan could be measured using this straightforward procedure in all hospital laboratories.

Evidence for the Hydration of Some Organic Compounds during Reverse-Phase HPLC Analysis

Some polar analytes (X) can reversibly form hydrates in water-containing eluents under the conditions of reversed-phase HPLC analysis, X + H2O ⇄ X × H2O. One of the methods to detect their formation is the recurrent approximation of the net retention times of such analytes, tR(C + ΔC) = atR(C) + b, where ΔC = const is the constant step in the variation of the organic modifier content of an eluent. These dependencies are linear if hydrates are not formed, but in the case of hydrate formation, they deviate from linearity under high water content. It has been shown that UV spectroscopic parameters, namely, relative optical densities: Arel = A(λ1)/A(λ2), depend on eluent composition for some organic compounds, but their variations cannot be used as indicators for hydrate formation. The coefficients that characterize the dependence of the analyte retention indices on the organic component concentration of an eluent, dRI/dC, appeared to be the most informative additional criterion for hydration. The values of these coefficients for most polar analytes are largely negative (dRI/dC < 0), whereas, for nonpolar compounds, they are largely positive (dRI/dC > 0).

Use of Stage-Wise AQbD and an Orthogonality Approach to Develop a Short-Runtime Method for the Simultaneous Quantification of Bosentan and Impurities using UPLC Equipped with PDA and ESI-MS

Analytical quality by design (AQbD) and method orthogonality are comprehensive tools used to develop an analytical method based on statistical and graphical evaluation. These tools provide complete knowledge of the method and help to develop precise, accurate, and specific methods. The present work elaborates the development of a selective and precise method for the quantification of bosentan and its nine impurities with a short runtime of 10 min using a statistically driven stage-wise AQbD approach with proven orthogonality. The optimum method was developed using 10 mM ammonium acetate pH 2.5 and acetonitrile in a gradient mode on an Agilent Zorbax Bonus RP RRHD 100 × 2.1 mm and 1.8 μm column with a flow rate of 0.45 mL/min at a column temperature of 40 °C. The robustness of the method was proven for the normal operating range (NOR) using Monte Carlo stimulations. The method was challenged using an orthogonal method that was developed based on the trellis graphs and surface response outcome of the design of experiment (DoE). The orthogonality factor between methods was calculated by measuring the correlation coefficient (r) of the retention factor (k') calculated for each peak on both methods. A forced degradation study was performed to challenge the method, and stressed samples were analyzed using both orthogonal methods. The outcome of the experiment proved that the approach of developing methods using the AQbD approach and then challenging them with orthogonality helps to develop a robust method. The method was further validated as per ICH guidelines.