[Do converting enzyme inhibitors differ from each other in the treatment of hypertension?]

Novel angiotensin converting enzyme inhibitors (ACE inhibitors) have recently been commercialized and the question arises whether differences in pharmacodynamic and pharmacokinetic properties should lead to specific therapeutic choices. To our knowledge there is no data which allows the physician to conclude to any different antihypertensive efficacy when ACE inhibitors are used at adequate dosage. Their pharmacokinetic characteristics may differ at every level: absorption, distribution, metabolism and excretion. Differences in chemical structure may also influence their diffusion in various tissues, therefrom the amplitude and duration of inhibition of angiotensin II at these sites. The duration of maximum blockade of ACE and the amplitude of residual blockade may theoretically influence the duration of the hypotensive effect and the number of daily dosages. Once-daily administered long acting ACE inhibitors keep their antihypertensive action through the whole 24-hour period, during chronic treatment. The theoretical advantage of such a property is an improved control of 24-hour blood pressure. However, no study, to our knowledge, concluded to any difference between long acting ACE inhibitors as far as this parameter was concerned. In addition, except captopril which has been reported to induce major untoward effects at the time high dosages were introduced, ACE inhibitors do not seem to bear different undesirable effects.