Omeprazole formulation

A method for preparing a stable oral pharmaceutical dosage formulation which consists of:

• (a) forming a pellet core consists of 10 to 50 weight percent based on the total weight of the core of omeprazole or a pharmaceutically acceptable salt, a surface active agent, a filler, a binder and 0.5 to 10 weight percent based on the total weight of the core of a pharmaceutically acceptable alkaline agent, wherein the alkaline agent is selected from the group consisting of lysine and arginine;
• and
• (b) applying an enteric coating directly onto the core without a separating layer wherein the enteric coating layer surrounds the core and consisting essentially of an enteric coating agent, 5 to 50 weight percent based on the total weight of the coating layer of an inert processing aid and optionally a plasticizer.