The Food & Drug Administration (FDA) recently approved safety label revisions for the multiple myeloma drug Revlimid (lenalidomide), adding a warning for patients with decreased kidney function. Kidney impairment causes the body to clear Revlimid more slowly than normal, and kidney impaired patients should therefore receive reduced dosages.

Revlimid is a novel therapeutic agent that has proven effective, often in combination with dexamethasone (Decadron), in treating initial and relapsed multiple myeloma. Unlike some drugs that are metabolized (broken down) in the liver, Revlimid actively circulates through the body until the kidneys filter and excrete it in urine. Consequently, when kidneys function slowly or ineffectively, the drug remains in the body longer. Patients therefore experience effectively greater Revlimid dosages, along with an increased risk of side effects.

For multiple myeloma patients, the normal starting dose of Revlimid is 25 mg/day on days 1 to 21 of repeated 28-day cycles. According to new recommendations, patients with moderate kidney impairment should only receive 10 mg/day, and patients with severe kidney impairment should only receive 15 mg every other day.

Guidelines define moderate kidney impairment as creatinine clearance between 30 to 60 mL/minute and severe kidney impairment as creatinine clearance below 30 mL/minute. The creatinine clearance test, which compares the levels of creatinine in the urine and blood, reflects how well the kidneys are filtering and therefore functioning.

For patients experiencing near or complete kidney failure, the guidelines recommend they receive 5 mg/day, and on dialysis days, drug administration should only occur after dialysis completes. Non-dialysis patients with creatinine clearances below 11 mL/min and dialysis patients with creatinine clearances below 7 mL/min have not yet been studied.

For more information, see the revised safety labeling announcement on the FDA Web site and a Medscape article covering the new changes (free registration required).