Contrasting the validation parameters and greenness of normal-phase and reverse-phase stability-indicating HPTLC methods for lemborexant analysis

There are very limited analytical procedures to determine lemborexant (LMB) in dosage forms and biological materials. However, the literature does not provide any "high-performance thin-layer chromatographic (HPTLC)" assays to determine LMB. In an effort to analyze LMB in commercial pharmaceutical tablets more precisely, accurately, and sustainably than with the normal-phase-HPTLC (NP-HPTLC) approach, a sensitive and greener reverse-phase-HPTLC (RP-HPTLC) method was developed and validated. For NP-HPTLC, an acetonepetroleum ether (40:60 v/v) developing system was used. However, ethanol-water (85:15 v/v) was the developing system for RP-HPTLC. Four different techniques, including the National Environmental Method Index (NEMI), Analytical Eco-Scale (AES), ChlorTox, and Analytical GREENness (AGREE), were used to evaluate the greenness of both procedures. LMB measurement was linear in the 50-500 and 20-1000 ng/band ranges, respectively for NP and RP procedures. RP procedure was more robust (uncertainties = 0.90-0.95 %), accurate (recoveries = 98.24-101.57 %), precise (uncertainties = 0.87-1.00 %), linear (20-1000 ng/band), sensitive (LOD = 0.92 ng/band and LOQ = 2.76 ng/band), and greener over NP procedure. The results of greenness assessment using NEMI (all four circles green), AES (93), ChlorTox (0.88 g), and AGREE (0.89) demonstrated that the RP strategy was greener than NP strategy and all other reported HPLC methods. The fact that both techniques can assess LMB when its degradation products are present implies that they both have characteristics that point to stability-indicating features. 89.24 % and 98.79 %, respectively, were the assay results for LMB in pharmaceutical tablets when utilizing the NP and RP procedures. Based on all validation and greenness metrics, it was found that RP procedure was better than the NP procedure. As a result, it is possible to assess LMB in pharmaceutical products using RP procedure.