[Why some proton pump inhibitors are more equal than others]

After the omeprazole patent expired in 2002, numerous generic products were introduced on the market. In a relatively short time many patients received substituted treatment. Clinicians noted a substantial number of patients with more reflux symptoms. We describe a male surgeon of 61 and a woman of 59 both with the red flag symptom of dysphagia after generic substitution. The first patient received a generic substitute of omeprazole, the second a therapeutic substitute of pantoprozole, i.e. omeprazole. The literature suggests three possibilities to explain the inadequacy of the substitution: (a) biphasic metabolism where the raised pH in the stomach may prematurely inactivate the PPI, with an unpredictable effect, (b) differences in acid-resistant coating of the generic products, and (c) influence of multiple dosing of PPIs after several days' use. We conclude that all three factors may contribute to a difference in absorption and therefore clinical effectiveness.