Calcium Gluconate and Magnesium Sulfate in Preventing Neurotoxicity in Patients With Colon Cancer or Rectal Cancer Receiving Oxaliplatin-Based Combination Chemotherapy

DISEASE CHARACTERISTICS: * Histologically confirmed adenocarcinoma of the colon or rectum * Has undergone curative resection and is considered to have stage II or III disease or completely resected stage IV disease with no evidence of residual tumor * Scheduled to receive 6 months of oxaliplatin-based adjuvant chemotherapy with 85 mg/m^2 oxaliplatin every 2 weeks (this includes, for instance, FOLFOX4 or modified FOLFOX6) * Patients receiving bevacizumab or cetuximab in combination with FOLFOX as part of a clinical trial or clinical practice are eligible PATIENT CHARACTERISTICS: * ECOG performance status 0-2 * WBC ≥ 3,000/mm^3 * ANC ≥ 1,500/mm^3 * Platelet count ≥ 100,000/mm^3 * Hemoglobin ≥ 10.0 g/dL * Total bilirubin ≤ 1.5 times upper limit of normal (ULN) * Serum creatinine ≤ 1.5 times ULN * Serum calcium ≤ 1.2 times ULN * Serum magnesium ≤ 1.2 times ULN * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * Able to complete questionnaires (alone or with assistance) * Able to comply with study treatment * Willing to return to enrolling institution for follow-up * Willing to provide blood sample for research purposes * No pre-existing peripheral neuropathy of any grade * No family history of a genetic/familial neuropathy * No second or third degree AV heart block or a history of second or third degree heart block * Bundle branch blocks are allowed. * No other medical conditions that, in the opinion of the treating physician, would make this protocol unreasonably hazardous for the patient PRIOR CONCURRENT THERAPY: * See Disease Characteristics * Central venous access line present, or scheduled to have a central line placed before starting chemotherapy and study treatment * No prior treatment with neurotoxic chemotherapy (e.g., oxaliplatin, cisplatin, taxanes, or vinca alkaloids) * No concurrent digitalis medication * No concurrent treatment with the anticonvulsants carbamazepine (e.g., Tegretol®), phenytoin (e.g., Dilantin®), valproic acid (e.g., Depakene®), gabapentin (Neurontin®), or pregabalin (Lyrica®) * No concurrent neurotropic agents, including venlafaxine (Effexor), desvenlafaxine (Pristiq®), milnacipran (Savella®), or duloxetine (Cymbalta) * No concurrent tricyclic antidepressants (such as amitryptilline), or any other agent specifically being given to prevent or treat neuropathy * No concurrent drugs given as a neuroprotectant