Patients with acute peptic ulcer, ulcerative colitis, Chron's disease or bowel obstruction were not included in clinical studies with Fosrenol. No data is available in patients with hepatic impairment. Caution should be exercised in these patients and monitoring liver function may be required. Patients with renal insufficiency may develop hypocalcemia. Serum calcium levels should, therefore, be monitored at regular intervals for this patient population and appropriate supplements given. The risk/benefit for longer-term administration (>2 years) should be carefully considered as experience with therapy beyond 2 years is limited.