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, she must be post-menopausal, not currently pregnant or nursing, and using a reliable contraception method (e.g., intrauterine device (IUD), oral or deport contraceptive, or barrier (i.e., condom or diaphragm plus spermicide). * The patient must sign an informed consent document indicating willingness to participate. Exclusion Criteria: * The patient has predominantly paroxysmal facial pain consistent with the diagnosis of classical trigeminal neuralgia or symptomatic trigeminal neuralgia. * The patient's facial pain has an identifiable cause. * The patient has a positive urine drug screen during the screening visit. * The patient has a history of substance abuse and/or dependency (including but not limited to opioid and/or alcohol dependence). * The patient has been on chronic opioid therapy or has taken opioid medication ≤ 7 days prior Pre-Screening. * The subject has a history of significant neurological, hepatic, renal, endocrine, cardiovascular, gastrointestinal, pulmonary, or metabolic disease. The subject has acute hepatitis or liver failure. * The subject has a history of left ventricular hypertrophy, recent MI, angina, palpitations, dyspnea, or arrhythmia. * The subject has used MAO Inhibitors within 30 days of enrollment. * The patient has a history of an allergic reaction to the components in the trial medication. * The patient is pregnant or breastfeeding. * The patient has a heart rate of less than 60 beats per minute and/or systolic blood pressure of 90 mmHg or lower at Screening and/or medication initiation visit. * The patient has another source of pain that is greater than AFP.