THA, 7-MEOTA, diazepam, 7-PhO-THA, and verapamil were used as reference compounds for comparison. Diazepam and verapamil represent drugs with low and high metabolic turnover, respectively . The HLM stability of these standards after 45 min of incubation was compared with the selected lead candidates (Table ). Consistent with literature data, verapamil exhibited experimentally high intrinsic clearance (CLint = 90.09 μL/min/mg) and a short half-life (t1/2 = 15.40 min).