Rapid and Highly Sensitive HPLC and TLC Methods for Quantitation of Amlodipine Besilate and Valsartan in Bulk Powder and in Pharmaceutical Dosage Forms and in Human Plasma

Abstract

Two simple, sensitive, and specific high-performance liquid chromatography and thin-layer chromatography methods were developed for the simultaneous estimation of Amlodipine besilate (AM) and Valsartan (VL). Separation by HPLC was achieved using a xTerra C18 column and methanol /acetonitrile /water/ 0.05% triethylamine in a ratio 40:20:30:10 by volume as mobile phase, pH was adjusted to 3 ± 0.1 with o-phosphoric acid. The flow rate was 1.2 mL min⁻¹. The linearity range was 0.2 to 2 µg mL⁻¹ for amlodipine besilate and 0.4 to 4 µg mL⁻¹ for Valsartan with a mean percentage recovery of 99.59 ± 0.523% and 100.61 ± 0.400% for amlodipine besilate and valsartan, respectively. The TLC method used silica gel 60 F₂₅₄ plates; the optimized mobile phase was ethyl acetate/ methanol / ammonium hydroxide (55:45:5 by volume). Quantitatively, the spots were scanned densitometrically at 237 nm. The range was 0.5–4.0 µg spot⁻¹ for amlodipine besilate and 2.0–12.0 µg spot⁻¹ for valsartan. The mean percentages recovery was 99.80 ± 0.451% and 100.61 ± 0.363% for amlodipine besilate and valsartan, respectively. The HPLC method was found to be simple, selective, precise, and reproducible for the estimation of both drugs from spiked human plasma.

Keywords:

• Amlodipine besilate
• HPLC
• TLC
• Valsartan

Notes

*The parameters were calculated using AM and VL as references.

equations obtained by the proposed methods.

^a Results of five determinations.

^b n = 3 × 3.

^c n = 3 × 3.

Figures in parentheses are the corresponding tabulated values at p = 0.05.

⁽³⁾HPLC method using (acetonitrile: methanol: solution of 7 ml triethylamine in a liter of water, pH 3 with phosphoric acid 15:35:50 by volume).

⁽¹³⁾HPLC method using (0.02 M phosphate buffer pH 3.2:acetonitrile 55:45 v/v).