Processes are provided for the identification a compound that is useful to treat or prevent a disorder that lowers the pH in a region of affected tissue comprising assessing the difference in potency, or potency boost, of the compound at physiological pH versus disorder-induced pH in a cell that expresses a human NMDA receptor. The assessment of potency boost can include measuring an IC50 of a compound at physiological pH and at disorder-induced pH (the “potency boost”) until a 95% confidence interval for the potency boost does not change more than 15% with the addition of a new experiment, wherein the measurements are repeated at least 5 times. The processes can be used for the selection of safe NMDA receptor antagonists for the treatment or prevention of a human disorder that lowers the pH in a region affected tissue. Such disorders include, but are not limited to, neuropathic pain, ischemic, Parkinsons disease, epilepsy and traumatic brain injuries.