s Method Development & Validation of LCMS/MS for Atorvastatin and Olmesartan in Human Plasma to Trace Drug Interaction of Formulation

Sensitive LC/MS/MS method was developed and validated to evaluate the bioavailability of cardiovascular formulation- Atorvastatin (ATSV) and Olmesartan (OLM), after administration of its combined formulation to hypertensive patients to mark the drug interaction. Blood samples (ATVS+OLM) were collected, centrifuged at 3000 rpm, at 4°C for 20min and stored at -20 °C until analysis. To the thawed 0.5 mL of sample, 50 μl IS (Rosuvastatin) solution of 50 ng/mL was added and vortex mixing was conducted for 30 sec. To 10Mm solution, about 2 μl of 10% Tris Buffer was added, then it was sonicated (1 min), extracted with adding 5mL of ethyl acetate, hand mixed (10 min) and centrifuged at 5000 rpm for 15 min. The upper organic layer (4 ml) was separated and evaporated to dryness at 45°C, using a gentle stream of N2 atmosphere. The residue was reconstituted in 200 μL of the mobile phase and was injected to the LC-MS/MS system. The developed method was validated for specificity, accuracy, precision, stability, linearity, sensitivity and recovery. It was successfully applied to detect the drug interaction of ATSV & OLM, where OLM conc. was significantly higher in its combination treatment as compared to the single OLM treatment. Thus, ATSV+OLM is least effective in combination instead of its expected synergistic activity.