By reducing the metabolism of drugs through these enzymes , cimetidine may increase their serum concentrations to toxic levels .
To be specific , cimetidine is an inhibitor of the P450 enzymes CYP1A2 , CYP2C9 , CYP2C19 , CYP2D6 , CYP2E1 , CYP3A4 .
By reducing the metabolism of drugs through these enzymes , inhibitor may increase enzymes ' serum concentrations to toxic levels .
To be specific , cimetidine is an inhibitor of the P450 enzymes CYP1A2 , CYP2C9 , CYP2C19 , CYP2D6 , CYP2E1 , CYP3A4 .