Validated liquid chromatographic ultraviolet method for the quantitation of Etoricoxib in human plasma using liquid–liquid extraction

A simple, sensitive and specific HPLC method with UV detection (284 nm) was developed and validated for quantitation of Etoricoxib in human plasma, the newest addition to the group of nonsteroidal anti-inflammatory drugs—a highly selective cyclooxygenase-2 inhibitor. Following a single-step liquid–liquid extraction with diethyl ether/dichloromethane (70/30, v/v), the analyte and internal standard (Zaleplon) were separated using an isocratic mobile phase of water/acetonitrile (58/42, v/v) on reverse phase Waters symmetry ® C 18 column. The lower limit of quantitation was 5 ng/mL, with a relative standard deviation of less than 20%. A linear range of 5–2500 ng/mL was established. This HPLC method was validated with between- and within-batch precision of 4.1–5.1% and 1.1–2.4%, respectively. The between- and within-batch bias was −3.8–4.7% and −0.6–9.4%, respectively. Frequently coadministered drugs did not interfere with the described methodology. Stability of Etoricoxib in plasma was >90%, with no evidence of degradation during sample processing (autosampler) and 30 days storage in a freezer. This validated method is sensitive and simple with between-batch precision of