Validated Absorption Factor Spectrophotometric and Reversed-Phase High-Performance Liquid Chromatographic Methods for the Determination of Ramipril and Olmesartan Medoxomil in Pharmaceutical Formulations

Abstract

Two simple and sensitive spectrophotometric and liquid chromatographic (LC) methods
are described for the determination of ramipril and olmesartan medoxomil. The first method was
based on the absorption factor. Ramipril and olmesartan medoxomil exhibit λmax at 210 nm and
256 nm respectively. Olmesartan medoxomil has some interference at 210nm, while ramipril do
not show any absorption at 256 nm.Quantitative estimation of ramipril was carried out by
subtracting the absorption due to olmesartan medoxomil at 210 nm using experimentally
calculated absorption factor. Beer’s law was obeyed for ramipril and olmesartan medoxomil at
2-6 Çg mL-1
and 8-24 Çg mL-1
respectively. The second method, high-performance liquid
chromatographic method was developed for the determination of ramipril and olmeasartan
medoxomil using sodium perchlorate: acetonitrile (60:40, v/v) as the mobile phase and
measuring the response at λmax 210 nm. The analysis was performed on a Phenomenex C8 (250
X 4.0 mm), 5 Çm column. The calibration curve was obtained for ramipril and olmesartan
medoxomil at 1-6 Çg mL-1
and 4-24 Çg mL-1
respectively. The mean recovery was 99.80 É
0.20% and 99.86 É 0.20% for ramipril and olmesartan medoxomil respectively. The methods
were validated according to the ICH guidelines.