Hypomagnesemia in patients treated with cetuximab

***

Hypomagnesemia in patients treated with cetuximab

F. Moreno Ramos, G. Casado Abad, S. Hernandez Garrido, E. Codes Cid, M.A. Tacoronte Fonturbel, A. Sierra Muñoz, A. Herrero Ambrosio

Hospital Universitario La Paz, Pharmacy, Madrid, Spain

Background:Cetuximab is a chimeric monoclonal antibody that inhibits the epidermal-growth-factor receptor (EGFR). EGF stimulates Mg2+ Henle´s loop reabsorption and in the renal distal convoluted tubule. Preliminary evidence suggests that magnesium wasting occurs in patients who are treated with cetuximab for colorectal cancer.

Methods: Prospective study in a cohort of 46 patients with colorectal cancer treated with cetuximab, between April and August 2008. We collected serum magnesium levels from the patients’ clinical report, chemotherapy protocols, maintenance cetuximab
dosage, and oral or intravenous magnesium replacement doses if necessary. Data from 24 patients were not available because the doctor did not request the analitical magnesium levels.

Results: 22 patients were evaluated, 12 men (54, 5%) and 10 women (45, 5%). In 17 patients serum magnesium levels remained below the normal limits (1, 8-2, 40 mg/dl), of which, 12 received oral magnesium and 2 were treated also with intravenous magnesium sulphate because of their low serum magnesium levels (1 mg/dl and 1, 4 mg/dl respectively). 5 patients remained within normal magnesium levels, and one did not received oral magnesium. The cetuximab dosage was maintained during this period.

Conclusions: Careful monitoring of serum magnesium is recomended during treatment, because symptoms of hypomagnesaemia can easily remain unrecognised. Our study suggests that oral magnesium substitution in patients with hypomagnesaemia is not efficient raising the magnesium to normal levels; however it controls magnesium levels avoiding a great decreasement in serum magnesium levels being effective for the maintenance of stable concentrations.

Reference: EAHP Congress Barcelona 2009