The present invention relates to novel microporous zirconium silicate compositions that are formulated to remove toxins e.g. potassium ions from the gastrointestinal tract at an elevated rate without causing undesirable side effects. The preferred formulations are designed avoid increase in pH of urine in patients and/or avoid potential entry of particles into the bloodstream of the patient. The present invention also relates to the use of the microporous zirconium silicate compositions in the treatment of diseases where the subject is not concurrently receiving lithium based drugs. Also disclosed is a method for preparing high purity crystals of ZS 9 exhibiting an enhanced level of potassium exchange capacity. These compositions are particularly useful in the therapeutic treatment of hyperkalemia.
