• Digoxin vs Omeprazole omeprazole will increase the level or effect of digoxin by increasing gastric pH. Applies only to oral form of both agents • Amoxicillin vs Cholera vaccine Avoid coadministration of cholera vaccine with systemic antibiotics since these agents may be active against the vaccine strain. • Metformin vs Amlodipine amlodipine decreases effects of metformin by pharmacodynamic antagonism. • Atorvastatin vs Clarithromycin clarithromycin will increase the level or effect of atorvas