*2.2. High Performance Liquid Chromatography (HPLC)*

Estimation of clarithromycin was done using a Jasco HPLC system (LC–4000, Easton, MD, USA) containing a degasser unit, pump, an automatic injector, as well as an MD– 4010 UV–Visible detector and a Phenomenex C-18 column (150 × 4.6 mm, i.d 5 µm). Chromatographic separation of clarithromycin was performed with the help of a mobile phase consisting of acetonitrile: potassium dihydrogen ortho-phosphate (0.02 mM) 40:60 *v*/*v*, adjusted to pH 5.5 with phosphoric acid [24]. The temperature in the HPLC column was set at 40 ◦C, and an isocratic elution of clarithromycin was achieved by allowing the solvent to flow at a fixed rate (1 mL/min) and was monitored at 210 nm. Regression analysis indicated good linearity when clarithromycin concentration was 30–400 ng/mL (r<sup>2</sup> = 0.990).
