Influence of oral magnesium-containing supplement and antacid administration on hypomagnesemia induced by panitumumab.

PURPOSE: Hypomagnesemia is a common side effect of panitumumab. The effect of magnesium-containing supplement as a laxative and concomitant antacid (proton pump inhibitor and histamine H2 antagonist) administration on panitumumab-induced hypomagnesemia was retrospectively investigated.

METHODS: Patients with advanced or recurrent colorectal cancer who received panitumumab were included in this study. Serum magnesium levels were extracted from the electronic medical records of 1753 administrations in 221 patients who received panitumumab. Serum magnesium levels in patients with or without oral magnesium-containing supplement and antacid treatment were compared using analysis of covariance as the number of panitumumab administration up to 16 times for covariates.

RESULTS: The mean serum magnesium levels were significantly decreased with increasing number of panitumumab administrations (2.13 mg/dL at 1st vs. 1.55 mg/dL at 16th, p < 0.001). The use of oral magnesium-containing supplement significantly inhibited the decline in mean serum magnesium level (1.98 mg/dL vs. 1.78 mg/dL, p < 0.001). However, antacid use in patients receiving oral magnesium-containing supplement significantly decreased the effectiveness of the magnesium supplement on serum magnesium level (2.02 mg/dL vs. 1.93 mg/dL, p < 0.05).

CONCLUSION: The use of oral magnesium-containing supplement might function as magnesium supplement based on the finding that use of oral magnesium-containing supplement during panitumumab administration decreased hypomagnesemia. However, combination of antacid decreased the supplemental effect of oral magnesium on hypomagnesemia. These results suggest the possibility that use of antacids during anti-EGFR antibody administration may promote hypomagnesemia.