The proton pump inhibitors rabeprazole, omeprazole, lansoprazole, and pantoprazole undergo an extensive hepatic biotransformation. In the liver, they are metabolized to varying degree by several cytochrome P450 (CYP) isoenzymes which are further categorized into subfamilies of related polymorphic gene products. The principal isoenzymes involved in the metabolism of proton pump inhibitors are CYP2C19 and CYP3A4. Of these two, minor mutations in CYP2C19 affect its activity in the liver and, in turn, the metabolic and pharmacokinetic profiles of the proton pump inhibitors. The metabolism of rabeprazole is less dependent on CYP2C19 and therefore is the least affected by this genetic polymorphism. Recent studies have brought to light the important role that this polymorphism plays in the therapeutic effectiveness of proton pump inhibitors during the treatment of acid-related diseases.
