Liquid chromatographic determination of 3-hydroxy-3-methylglutaryl coenzyme a reductase inhibitors

Reversed-phase high-performance liquid chromatography CRP-HPLC) was used as a tool to explore the retention behavior and separation of four 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, namely compactin, lovastatin, simvastatin, and pravastatin in their hydroxy acid and lactone forms. The contribution of C-6 and C-2' methyl groups and lactonization to the molecular hydrophobicity among these four structurally related HMG-CoA reductase inhibitors were elucidated. Eight components (four lactones and four hydroxy acids) could be resolved by RP-HPLC with isocratic elution. In a binary mobile phase system of acetonitrile-water containing 0.5% acetic acid, the free hydroxy acids and corresponding lactone forms remained intact and were completely separated. This study demonstrated that RP-HPLC is suitable for simultaneous determination of active and prodrug forms of these HMG-CoA reductase inhibitors.