Analytical quality-by-design optimization of UHPLC method for the analysis of octreotide release from a peptide-based hydrogel in-vitro.

In this article, a UHPLC-PDA method has been developed using the quality-by-design (QbD) principles for the determination of the therapeutic peptide - octreotide - in its in vitro released samples. Due to the complexity of the peptide-based hydrogel matrix a reliable separation of the analyte from the matrix has to be performed. Risk assessment and multivariate analysis were employed for the method evaluation. Following method scouting towards the selection of appropriate and rapid UHPLC operative mode, quality risk assessment tools were applied to set the critical method parameters (CMPs) to be considered in screening phase. The effects of CMPs on critical method attributes (CMAs) were assessed further by means of a screening design. A response surface methodology was utilized to model CMAs as a function of the selected CMPs and the optimum separation conditions were additionally evaluated using desirability function. The method operable design region was complimented by establishment of a robust zone using Monte Carlo simulation and capability analysis. The method was validated in the range of 1 - 20 μg /mL using the accuracy profiles as a graphical decision-making tool. The β-expectation tolerance intervals was within the pre-set acceptance criteria of ± 10% meaning that 95% of future results will be included in the defined bias limits. The relative bias was varied between ─ 0.8% and 1.4% and the RSD values for repeatability and intermediate precision were below to 2.8% in all cases. The achieved limit of detection (LOD) and the lower limit of quantification (LLOQ) were adequate for the specific purpose and found to be 0.3 and 1 μg /mL, respectively. The developed method was successfully applied to the analysis of octreotide in in-vitro drug release samples obtained from peptide-based hydrogels.