LC/MS pharmacokinetic assay of an API from a novel class of selective cholesterol absorption inhibitors and of its glucuronide, on an ASTRA® C18-HE, 5 µm column (150 mm × 4.6 mm, AST-5732-LK46). Isocratic elution with MeOH : ACN : water : 0.1 % NH4OH 25/50/20/5 (v/v/v/v) at 0.45 ml/min, ambient temperature, injection volume 15 µl. Detection by MS/MS on a TSQ Quantiva (Thermo Fisher Scientific) in negative ESI mode at 2500 eV, capillary 350 °C, vaporizer 380 °C, argon as collision gas; transitions 588 → 275 (API glucuronide D4) and 412 → 275 (API D) at 2 mTorr and 29 eV. The peak area stays stable over more than 200 injections of plasma samples, which documents the column lifetime in this assay.