Results of phase I/II clinical trials with ezetimibe, a novel selective cholesterol absorption inhibitor

Phase I/II studies in patients with hypercholesterolaemia have explored the safety and efficacy of ezetimibe mono-therapy and co-administration with a statin. In an 8-week dose-ranging study, daily doses of 1–40 mg of ezetimibe reduced low-density lipoprotein cholesterol (LDL-C) levels in a fairly flat dose-dependent manner. A second dose-ranging study confirmed that optimal efficacy, of 19% reduction in LDL-C level at 12 weeks, was achieved with the 10-mg dose. A dose-regimen, or dose-scheduling, study of morning versus evening dosing produced similar reductions of LDL-C levels, showing that timing of dosing does not affect treatment response. Pooled efficacy results from these two monotherapy studies confirmed that ezetimibe 10 mg.day−1 significantly (⁠ \(P{<}0{·}05\) ⁠) reduced LDL-C levels by approximately 18%; ezetimibe also reduced triglyceride levels by approximately 5% and increased high-density lipoprotein cholesterol levels by approximately 3·5%. An additional study of 10 mg of ezetimibe co-administered with 10 mg of simvastatian showed that ezetimibe does not affect the pharmacokinetics of the statin and provides a 17% additive reduction in LDL-C levels compared with simvastatin monotherapy. Other studies with ezetimibe indicate minimal potential for drug interactions. Ongoing phase III trials are expected to confirm that ezetimibe, alone or in combination with a statin and as an adjunct to diet, provides consistent and predictable reductions in LDL-C level of 18%, with no new or worsened statin-related side-effects.