An oral solid pharmaceutical dosage form comprising an acid sensitive proton pump inhibitor (PPI) as single active drug, releasing the PPI in two separate pulses, one immediate and one delayed. The PPI is formulated into a core material in the form of pellets, which are coated i.a. with a combination of a delayed release modifying layer and a lag time controlling layer. The pellets are further provided with an enteric coating layer. The application also relates to processes for preparing the dosage forms as well as their use in the treatment of gastrointestinal diseases.