Abstract: The present invention relates to stable liquid formulations that comprise a water free or almost water free, polyethylene glycol solution of sodium or potassium salt of a H+, K+-ATPase inhibitor of Formula I or a sodium or potassium salt of one single enantiomer thereof. Alternatively, the sodium or potassium salt of the H+, K+-ATPase inhibitor may be formed in situ in the polyethylene glycol solution by adding sodium or potassium hydroxide together and the active compound. The invention is also directed to the preparation of the claimed formulation, use of the stable liquid formulations in medicine and in the treatment of gastrointestinal diseases.