Memantine XR and Pregabalin for Chemotherapy-Induced Peripheral Neuropathy

Inclusion Criteria: Ability to understand and the willingness to sign a written informed consent. History of any type of cancer treated with chemotherapy. Chemotherapy induced peripheral neuropathy (CIPN) due to: * Cisplatin, carboplatin, and oxaliplatin * Taxanes- paclitaxel, docetaxel, and cabazitaxel * Thalidomide, lenalidomide, and pomalidomide * Plant alkaloids, such as vinblastine, vincristine, vinorelbine, and etoposide * Epothilones, such as ixabepilone * Bortezomib, carfilzomib * Eribulin Planning to receive treatment for CIPN with memantine XR and pregabalin. Average daily neuropathic pain intensity \> 4 measured by item #5 of BPI-SF (Average daily pain at baseline is the average of pain scores over the last 7 days before enrolling patients in to the study). CIPN \> grade 1 as measured by NCI-CTCAE v 4.0. Must be ≥ 3 months beyond completion of chemotherapy. Not planning to receive concurrent chemotherapeutic agents during the study period. Patients with diabetes mellitus, peripheral vascular disease, HIV infection, or a significant degenerative or familial neurologic can be included in the study provided they don't have peripheral neuropathy secondary to above mentioned diseases. Allowable types and amount of prior therapy for neuropathy: * Patients receiving analgesics for pain associated with CIPN are eligible provided they have taken the same dosage and same medication for at least 2 weeks prior to the study initiation. * Patients on antidepressants regimens of Selective Serotonin Reuptake Inhibitors (SSRI) or Selective serotonin norepinephrine reuptake inhibitors (SSNRI) for treatment of anxiety or depression, anticonvulsants or mexiletine for the treatment of pain are eligible provided they are on stable dose for 30 days. Age ≥ 18 years. Both men and women of all races and ethnic groups are eligible for this trial. Exclusion Criteria: Any pain other than neuropathic pain of equal or greater severity. Patients with sensory polyneuropathy due to AIDS/HIV, complex regional pain syndrome, and Trigeminal neuralgia. History of suicidal ideation. Patients with a history of non-compliance. Patients who are judged by the investigator to be unable or unlikely to understand the nature, scope, and possible consequences of the study.