tokens: METHODS : We determined an odds ratio ( OR ) , as a measure of the relative risk of being exposed to a potential interaction , comparing the use of the H2-receptor antagonist , cimetidine , with that of the noninteracting agents ranitidine , famotidine and nizatidine in users and nonusers of warfarin , phenytoin and theophylline .
folded_tokens: method : we determine a odds ratio ( or ) , as a measure of the relative risk of be expose to a potential interaction , compare the use of the h2-receptor antagonist , cimetidine , with that of the noninteracting agent ranitidine , famotidine and nizatidine in user and nonuser of warfarin , phenytoin and theophylline .