The invention provides: (1) novel sodium-containing omeprazole salts formed by the reaction of omeprazole and a sodium source in a crystallization solvent; (2) novel zinc-containing omeprazole salts formed by the reaction of omeprazole and a zinc source in a crystallization solvent, including salts formed by the recrystallization of a zinc salt in a reaction mixture comprising a sodium-containing omeprazole salt and a crystallization solvent; and (3) methods of treatment which use the novel salts to treat or prevent gastric acid-related diseases.