Lercanidipine: Short Plasma Half-life, Long Duration of Action and High Cholesterol tolerance: Updated Molecular Model to Rationalize its Pharmacokinetic Properties

Abstract

Calcium-channel antagonist drugs of the 1,4-dihydropyridine type have been shown to bind to the L-type calcium channel. These drugs are not only amphiphilic, but new molecular designs have become increasingly lipophilic and can readily transport across cell membranes, accessing both hydrophilic and hydrophobic environments, despite becoming more soluble in the membrane bilayer. This biophysical understanding appears not only to define the molecular pathways for drug binding to the calcium-channel receptor, but also to explain differences in the overall clinical pharmacokinetics observed for different drugs in this class. The pharmacokinetic profile of calcium antagonists, although influenced to some degree by interactions with their target calcium-channel receptor, appears to be largely dictated by their interactions with cell membranes at the molecular level. There appears to be a correlation between the duration of action of such membrane-active drugs and the membrane partition coefficient in conjunction with the washout rate. This class of drugs has evolved from a drug such as amlodipine, with a long duration of action related to prolonged plasma half-life, to lercanidipine, which has the shortest plasma half-life relative to its intrinsically long duration of action. Recently, it was discovered that membrane cholesterol reduces the amount of calcium-channel antagonist that can partition into the membrane. Atherosclerotic disease results in increased levels of membrane cholesterol in smooth muscle cells. Latest generation calcium antagonists, which have a long duration of action, can better overcome this negative effect. Lercanidipine has now been shown to have one of the highest measured tolerances to cholesterol, which may indicate its ability to treat a broad range of hypertensive patients with varying degrees of progressive atherosclerotic disease. On what criteria should the effectiveness of calcium antagonists be evaluated? A good calcium antangonist needs to exhibit a placebo-like side-effect profile, thus ensuring good patient compliance. However, an intrinsically long-lasting, once-a-day dose is also pharmacokinetically desirable. To be a truly optimal calcium antagonist, it should function and be efficacious over a broad range of hypertensive patients. It should be able to control blood pressure in light of other complications such as progressive atherosclerotic disease. Recent studies indicate that during the progression of atherosclerosis, cholesterol levels within cell membranes of the arterial wall increase, a process that can reduce the effective concentration of calcium antagonists in these membranes. What is needed is a calcium antagonist that is slow acting to reduce vasodilatory induced side-effects and intrinsically long lasting to ensure once-a-day dosage, and that possesses a high cholesterol tolerance factor to overcome the molecular and compositional changes taking place in the arterial wall, so that it can treat effectively a broad range of hypertensive patients.