Bioequivalence and Bioavailability Forum

❝ Please inform me regarding effect of xanthine containing food and beverages

❝ and Tobacco containing product on drug bioavailability

• Methyl(!)xanthines (see this post). There may be interactions if your drug is a substrate or inhibitor of Xanthine oxidase.
  
• Tobacco smoke induces Cytochrome P450 1A2 (and CYP P450 1A1?). If your API is a substrate, you may get lower concentrations. One the other hand, deprivation of smoking may lead to stress, which has effects on circulation, etc. Therefore in a BE study preferably non-smokers or moderate smokers should be included.