Ivermectin

Ivermectin and Ivermectin-d₂ were products of Toronto Research Chemicals (Toronto, Canada). Gradient grade water and methanol as well as formic acid (98–100%) were purchased from Merck (Darmstadt, Germany). Dimethyl sulfoxide (DMSO), ketoconazole, ammonium formate (eluent additive for liquid chromatography–mass spectrometry, LC–MS), bovine serum albumin (BSA), potassium phosphate monobasic (1 M KH₂PO₄), and potassium phosphate dibasic (1 M K₂HPO₄) were obtained from Sigma-Aldrich (St. Louis, MO, USA). Recombinant human (rh) CYP3A4 supersomes, rh CYP3A5 supersomes, nicotinamide adenine dinucleotide phosphate (NADPH) regenerating solution A (26 mM NADP+, 66 mM glucose-6-phosphate, and 66 mM MgCl2 in H₂O) and solution B (40 U/mL glucose-6-phosphate dehydrogenase, in 5 mM sodium citrate) were purchased from Corning Life Sciences B.V. (Amsterdam, The Netherlands). Drug-free human blood, stabilised by citrate–phosphate-derivative with adenine was acquired from the local blood donation centre (Basel, Switzerland).

Ammonium format and dimethyl sulfoxide (DMSO) were purchased from Sigma-Aldrich (Buchs, Switzerland). Gradient grade methanol, water, formic acid (FoA, 98–100%), isopropyl alcohol, and acetonitrile were products of Merck (Darmstadt, Germany). Human blank blood, stabilised by citrate-phosphate-derivative with adenine, was obtained from the local blood donation centre.
Ivermectin and ritonavir as well as the internal standard Ivermectin-d₂ were purchased from Toronto Research Chemicals (Toronto, Canada). Rifampicin, ketoconazole, and piperonyl butoxide were obtained from Sigma-Aldrich.