Efficacy and Safety of ATNC05 in Treatment of Atypical Facial Pain

Inclusion Criteria: * The patient is at least 18 years but no more than 89 years of age * The patient has atypical facial pain/persistent idiopathic facial pain, as diagnosed by the 2nd Edition of The International Headache Classification (ICHD-2), section 13.18.4. * The patient has constant pain in the face, persisting for all or most of the day (four or more hours per day) and present four days or more per week, with a severity of 5 or more (11-point scale, 0 = no pain, 10 = worst pain imaginable). * The pain is chronic, present for at least six months. * The patient's pain is confined at onset to a limited area on one side of the face, and is deep and poorly localized. * The patient's pain is not associated with sensory loss or other physical signs, and diagnostic studies of face and jaws do not demonstrate any relevant abnormality. * Patient must be willing to refrain from opioid medications during the course of the trial. * Patients entering the study on other approved concomitant medications for pain (e.g., NSAIDS, anticonvulsants, antidepressants) must continue them as a stable regimen for at least two weeks prior to Pre-Screening and throughout the study period. * The patient must agree to limit their rescue medications to APAP (Paracetamol/ acetaminophen). * The patient must understand and be willing to cooperate with the study instructions, including attendance of all scheduled office visits and returning unused medication and vials. * If the patient is a female, s…