This invention comprises the use of compounds of formula (I) wherein the dotted line represents an optional bond; X is oxygen or sulfur; R1is hydrogen, C1-12alkyl, Ar1, Ar2C1-6alkyl, quinolinylC1-6alkyul, pyridylC1-6alkyl, hydroxyC1-6alkyl, C1-6alkyloxyC1-6alkyl, mono- or di(C1-6alkyl)aminoC1-6alkyl, aminoC1-6alkyl, or a radical of formula —Alk1—C(=))—R9or —Alk1—S(O)2—R9; R2, R3and R16each independently are hydrogen, hydroxy, halo, cyano, C1-6alkyl, C1-6alkyloxy, hydroxyC1-6alkyloxy, C1-6alkyloxyC1-6alkyloxy, aminoC1-6alkyloxy, mono- or di(C1-6alkyl)aminoC1-6alkyloxy, Ar1Ar2C1-6alkyl, Ar2-oxy, Ar2C1-6alkyloxy, hydroxycarbonyl, C1-6alkyloxycarbonyl, trihalomethyl, trihalomethoxy, C2-6alkenyl; R4and R5each independently are hydrogen, halo, Ar1, C1-6-alkyl, hydroxyC1-6alkyl, C1-6alkyloxyC1-6alkyl, C1-6alkyloxy, C1-6alkylthio, amino, hydroxycarbony, C1-6alkyloxycarbonyl, C1-6alkylS(O)C1-6alkul or C1-6alkylS(O)2C1-6alkyl; R6and R7independenly are hydrogen, halo, cyano, C1-6alkyl, 4,4-dimethyl-oxazolyl, C1-6alkyloxy or Ar2oxyl R8is hydrogen, C1-6alkyl, cyano, hydroxycarbonyl, C1-6alkyloxycarbonyl, C1-6alkylcarbonylC1-6alkyl, cyanoC1-6alkyl, C1-6alkyloxycarbonylC1-6alkyl, carboxyC1-6alkyl, hydroxyC1-6alkyl, aminoC1-6alkyl, mono- or di(C1-6alkyl)aminoC1-6alkyl, imidazolyl, haloC1-6alkyl, C1-6alkyloxyC1-6alkyl, aminocarbonylC1-6alkyl, or a radical of formula —O—R10, —S—R10, —N—R11R12; R17is hydrogen, halo, cyano, C1-6alkyl, C106alkyloxycarbonyl, Ar1; R18is hydrogen, C1-6alkyl, C1-6alkyloxy or halo; R19is hydrogen or C1-6alkyl; for the manufacture of a medicament to inhibit smooth muscle cell proliferation.