In this paper it is demonstrated that by adequate selection of topological
descriptors we can make possible the prediction of different pharmacologica
l properties, such as plasmatic concentration or sedative effect, within a
group of antihistaminic drugs. Moreover, also demonstrated is the usefulnes
s of molecular connectivity in the search of new active compounds. Examples
of such compounds are 4-(1-buthylpenthyl)pyridine, N-(3-bromopropyl)-phtal
imide and N-(3-chlorpropyl)-piperidin hydrochloride. All of them show antih
istaminic activity values more than 30% higher than that of terfenadine, wh
ich is used as the reference drug.