Quantitative determination of saquinavir from Caco-2 cell monolayers by HPLC-UV. High performance liquid...

The validation and quantitative determination of the protease inhibitor, saquinavir, from confluent Caco-2 monolayers and from aqueous solution is reported. The high performance liquid chromatographic method consisted of an Ultramex 5 C(8) reverse-phase column (250 x 4.6 mm i.d.) and a mobile phase of acetonitrile:water:triethylamine (55:44:1, v/v/v, pH 6.5). Samples were analyzed using an ultraviolet detector at 238 nm, and diltiazem hydrochloride (66 micro g/mL) was used as an internal standard. A linear response over a broad concentration range (0.4-8.0 micro g/mL, r(2) = 0.997) was obtained. The limit of detection and quantitation was set at 0.14 and 0.4 micro g/mL, respectively. Over a 4 day period, the intra-day and inter-day precision ranged from 1 to 7% with a mean of 4%, and from 1 to 2% with a mean of 1.5%, respectively. Bench-top and storage stability of saquinavir was found to be satisfactory. The permeability of saquinavir through Caco-2 monolayers was estimated using this assay.