From the December 2004 Issue

Shire Pharmaceuticals recently announced that FOSRENOL (lanthanum carbonate), used to reduce serum phosphate levels in patients with end-stage renal disease (ESRD), has been approved by the FDA and will soon be available. In January 2003, we became aware that this medication was undergoing FDA review. At that time, we alerted readers that the generic name could look like lithium carbonate when poorly handwritten. The names could also sound similar. This may contribute to a great deal of confusion, especially at sites where prescribing by the generic name is encouraged. The risk of error is increased because the dosage ranges for these drugs are similar and may overlap. Lanthanum carbonate is a chewable tablet that will be available in 250 mg and 500 mg tablets. It should be administered in divided doses with meals and patients will generally require 750 to 3,000 mg daily. Lithium carbonate doses typically range from 300 to 1,800 mg daily and also may be administered in divided doses with meals.

A mix-up could be harmful given that lanthanum will be used in ESRD patients where the risk of lithium toxicity is high. Including the indication as well both the brand and generic name on prescriptions will help to minimize this problem. If this information is not provided, pharmacists should verify the purpose of the medication with the patient.