Cisplatin Injection and Lithium: Interaction Details

a) Decreased serum lithium concentrations without psychiatric decompensation were reported within 24 hours of initiation of bleomycin, etoposide, and CISplatin (BEP) chemotherapy in a 33-year-old man with metastatic testicular cancer and bipolar affective disorder. The patient, who was institutionalized, had chronically been taking lithium carbonate 400 mg in the morning and 600 mg in the evening, with serum lithium levels of 0.6 to 0.9 mmol/L (therapeutic range, 0.3 to 1.3 mmol/L). Concomitant medications included biperidene 2 mg/day, promethazine 50 mg/day, carbamazepine 400 mg/day, temazepam 20 mg/day, haloperidol 10 mg/day, and disulfiram 500 mg/day when the chemotherapy regimen of etoposide 120 mg/m(2) on days 1 through 3, bleomycin 30 mg on day 2, and CISplatin 20 mg/m(2) on days 1 through 5 and the supportive agents ondansetron 8 mg IV three times daily on days 1 through 5 and hydration with normal saline 4.5 L/day that included calcium, magnesium, and potassium on days 1 through 5 began. On day 2 of BEP, lithium levels decreased from 0.61 mmol/L to 0.22 mmol/L and transiently increased back to baseline by day 8 without any change of lithium dosage. A similar, although less pronounced, pattern of decrease of lithium levels and transient increase back to near baseline by day 8 occurred during 3 subsequent courses of BEP ¹.

b) Decreased serum lithium concentrations without psychiatric decompensation were reported within 24 hours of initiation of CISplatin in a 36-year-old woman with metastatic tongue cancer and bipolar affective disorder. The patient had chronically been taking lithium carbonate 300 mg four times daily, which maintained serum lithium levels at 1 mEq/L. No other medications were reported when one dose of CISplatin 100 mg/m(2) was given along with 24 hours of fluid hydration that included normal saline 1 L, mannitol 25 g bolus, mannitol 20% 1 L infusion, and D5NS 1 L with calcium, magnesium, and potassium supplementation. Lithium levels decreased from 1 mEq/L to 0.3mEq/L after administration of CISplatin and fluid load; no change of lithium dosage occurred and levels recovered to near baseline within 48 hours of chemotherapy. A similar decrease of lithium levels, although less pronounced (from 0.8 to 0.5 mEq/L), occurred during a second course of CISplatin therapy ².