A dearth of data: the problem of phosphorus in prescription medications.

A high dietary intake of phosphorus is considered by most to be a significant health threat for dialysis patients. Efforts to include the phosphorus content of foods on the nutrition label in the US have, to date, been fruitless. Another source of phosphorus, largely unrecognized, is prescription medications. These may contain phosphorus as indicated on their package label; the amount is not quantified. We examined the labels of the branded forms of 200 of the most widely prescribed medications in Dialysis Clinic centers in the United States and found that 23 (11.5%) contained phosphorus. A sampling of different doses and manufacturers (generic and branded) of these drugs was analyzed for phosphorus content and found levels as high as 111.5 mg/dose (40 mg paroxetine). Notable were the phosphorus content of a generic 10 mg lisinopril (32.6 mg) and a generic 10 mg amlodipine (40.1 mg). The significant potential for iatrogenic injury accruing from the use of these drugs warrants efforts at remediation. Specific information on the phosphorus content of medications used by dialysis population needs to be made available to the dialysis community.

The Phosphate Content of Prescription Medication: A New Consideration.

BACKGROUND: Phosphate restriction is needed in most dialysis patients. The package inserts from some medications indicate that phosphate may be part of the excipient fraction of drugs. It is unclear whether its amount may be clinically significant since the phosphate content is unquantified. METHODS: We reviewed the package inserts for the branded formulations of the most widely used drugs at a dialysis chain. We measured the phosphate levels in a sample of the branded form of these drugs and some of their generic formulations. We also reviewed the available package inserts of 16 selected generic drug manufacturers for the presence of phosphate in drugs that were phosphate free in their branded formulation. RESULTS: We identified 12 prescription products that contained phosphate, 9 of which contained clinically significant quantities (>10 mg per daily dose) notably in both branded and generic forms of amlodipine, lisinopril, paroxetine and bisoprolol. Phosphate was rarely present in a generic drug when its corresponding branded formulation was phosphate free. CONCLUSION: Commonly prescribed drugs may contain clinically important levels of phosphate.