Interaction of oral anticoagulants with methyl xanthines

The interaction of warfarin and dicumarol with methyl xanthines was monitored. The results revealed formation of equimolar complexes with both caffeine and theophylline. The interaction is exothermic and complexation is thermodynamically unfavourable. The apparent solubility of dicumarol in water was found to increase linearly with increasing methyl xanthine concentration. The dissolution rate of the prepared complexes is higher than that of their respective physical mixtures or the respective drug per se. The implication of such interaction on the biological performance of the two anticoagulants was assessed in Albino rabbits. The results indicate that incorporation of dicumarol in form of a complex or even as a physical mixture with methyl xanthines does affect the biological performance of the drug to a marked extent.