Comparison of the effect of colchicine and vinblastine on the inhibiton of dentinogenesis in rat incisors.

The quantitative effect of vinblastine, colchicine and lumicolchicine on the rate of dentine formation was determined by chronologically-labelling dentine with the lead salt of EDTA, before and after the intravenous administration of the test drug. Colchicine and vinblastine produced a dose-dependent inhibition of dentine formation. Lumicolchicine had no adverse effect. Although the log dose-response lines of colchicine and vinblastine were parallel, the effect of vinblastine was more potent. The relative potency ratio of vinblastine to colchicine was 1.25-1.70. These results suggest that both colchicine and vinblastine may act at the same site i.e. microtubules, thereby inhibiting the secretion of new dentine matrix.