Quantitative determination of combination of amlodipine besylate and telmisartan in tablets using 1H-qNMR and its comparison to HPLC for further validation

Abstract

Background HPLC and LC–MS are traditional drug-analysis methods, while 1H-qNMR is increasingly popular as it is a non-destructive technique which does not require standards and enables efficient analysis of complex mixtures. Methods This study used 1H-qNMR for the quantitative determination of amlodipine besylate and telmisartan in tablets, and HPLC was employed for comparison. Results The 1H-qNMR and HPLC methods showed strong linearity over concentration ranges of 1.0–5.00 mg/mL and 0.005–0.1 mg/mL, respectively, with regression coefficients (R²) greater than 0.99, indicating excellent linearity. In addition, the limit of detection and limit of quantification values determined using 1H-qNMR were 0.328 and 1.09 mg/mL for amlodipine besylate and 0.277 and 0.923 mg/mL for telmisartan. The HPLC method yielded LOD and LOQ values of 0.0836 and 0.2533 µg/mL for amlodipine besylate and 0.0434 and 0.1446 µg/mL for telmisartan, respectively. Standard deviations and % RSD for recovery tests of all samples were found to be within 0.41–1.54 and 0.005–1.55%, respectively. The results of the recovery test demonstrated that the signals at δ H 2.63 (H-39) and δ H 5.63 (H-16) ppm of telmisartan and δ H 2.31 (H-22) and δ H 5.31 (H-4) ppm of amlodipine besylate showed a more reliable recovery percentage with considerable standard deviation and RSD %. Conclusion A 1H-qNMR method was developed to determine the content of amlodipine besylate and telmisartan in tablets and validated using HPLC analysis. It enables the simultaneous quantification of both drugs in fixed-dose combination tablets, supporting accurate dosage control and effective therapeutic management.