ObjectivesTo investigate a possible relationship between the time courses of action of various calcium antagonists and their lipophilicity, characterized as logP-values.MethodsThe functional experiments were performedin vitroin human small subcutaneous arteries (internal diameter 591 ± 51 μm,n= 7 for each concentration), obtained from cosmetic surgery (mamma reduction and abdominoplasty). The vessels were investigated in an isometric wire myograph. The vasodilator effect of the calcium antagonists was quantified by means of log IC50-values, and the onset of the vasodilator effect for each concentration studied was expressed as time to Eeq90-values (time to reach 90% of the maximal effect).ResultsLog IC50-values were −8.46 ± 0.09, −8.33 ± 0.25 and −8.72 ± 0.16 for nifedipine, felodipine and (S)-lercanidipine, respectively (not significant). On average, nifedipine reached time to Eeq90in 11 ± 1 min. For felodipine and (S)-lercanidipine the corresponding values were 60 ± 11min and 99 ± 9 min, respectively. The differences between these values were statistically significant (P< 0.01). In spite of these differences in the invitro human vascular model, the three calcium antagonists are equipotent with regard to their vasodilator effects. Linear regression analysis of the correlation between the logarithm of the membrane partition coefficient (logP-values) of the calcium antagonists tested [2.50, 4.46 and 6.88 for nifedipine, felodipine and (S)-lercanidipine, respectively] and their respective values found for time to Eeq90was highly significant.ConclusionsIt appears that a higher logP-value is correlated with a slower onset of action.