The classification of calcium antagonists and their selection in the treatment of hypertension. A reappraisal.

Calcium antagonists have become one of the most important advances in the treatment of hypertension since their introduction over 20 years ago. The increase in the number of available calcium antagonists (as new formulations of pre-existing drugs or new chemical entities) over recent years has contributed to an ever-changing scenario regarding their appropriate use compared with other antihypertensive agents. As a consequence of this evolving situation, several authors have proposed a 3-generation classification of calcium antagonists currently, or soon to be, marketed in several counties. The classification system is based among other variables, on chemical structure, tissue selectivity, administration frequency and duration of action. In this article, this classification is reviewed and updated on the basis of new information that is available. In addition, factors which influence the selection of calcium antagonists in the treatment of hypertension in specific patient populations are discussed. As well as pharmacodynamic and pharmacokinetic considerations, these factors also include previous experience with particular drugs in specific patient populations, cost of treatment and drug interactions. Among the dihydropyridine calcium antagonists, the first generation compounds have been clearly superseded and are not recommended for use in hypertensive patients. Whilst the second generation agents represent an adequate treatment, third generation calcium antagonists possess distinct advantages. Definitive confirmation of the role of calcium antagonists in hypertension lies in several ongoing large multicentre trials.