PO (Adults and children >17 yr): 500 mg twice daily; may increase by 500 mg at weekly intervals up to 2000 mg/day. If doses >2000 mg/day are required, give in 3 divided doses (not to exceed 2500 mg/day) or 850 mg once daily; may increase by 850 mg at 2-wk intervals (in divided doses) up to 2550 mg/day in divided doses (up to 850 mg 3 times daily); Extended-release tablets —500–1000 mg once daily with evening meal, may increase by 500 mg at weekly intervals up to 2500 mg once daily. If 2000 mg once daily is inadequate, 1000 mg twice daily may be used.
PO (Children >10 yr): 500 mg twice daily, may be increased by 500 mg/day at 1–wk intervals, up to 2000 mg/day in 2 divided doses.
Renal disease or dysfunction as suggested by serum creatinine of 1.5 mg/dL or higher in men or 1.4 mg/dL or higher in women, or abnormal CrCl; conditions that predispose to renal function impairment (eg, CV collapse, acute MI, septicemia); in patients undergoing radiologic studies involving parenteral administration of iodinated contrast material (potential to acutely alter renal function); acute or chronic metabolic acidosis, including diabetic ketoacidosis; CHF requiring pharmacologic treatment; hypersensitivity to any component of the product.