Efficacy of Guanfacine and Lidocaine Combination in Trigeminal Nerve Block for Pain Management in Trigeminal Neuropathy

A Randomized, Double-Blind, 2-Way Crossover Trial to Assess the Efficacy of Guanfacine and Lidocaine Combination Versus Lidocaine Alone in Trigeminal Nerve Block for Pain Management in Painful Trigeminal Neuropathy Patients

A phenome-wide association study (PheWAS) identified an association between a loss of function variant in the human alpha 2B adrenergic receptor gene and trigeminal nerve disorders. Guanfacine is the oldest alpha-2 adrenergic agonist in clinical use and is approved for hypertension and attention deficit hyperactivity disorder. We hypothesize that guanfacine will be an effective adjunct to lidocaine for the treatment of neuropathic pain by enhancing and prolonging pain relief due to its activation of alpha-2 adrenergic receptors. The objectives of the study will be to evaluate the efficacy and safety of guanfacine in combination with lidocaine for trigeminal nerve block procedures for pain management in trigeminal neuralgia patients. This study will evaluate the efficacy of guanfacine in reducing acute pain and extending duration of pain relief when delivered in combination with lidocaine as a trigeminal nerve block, measured by Visual Analog Scale (VAS) data collected at specific time points after each injection.

Inclusion Criteria:

• Ability to understand and read English
• History of painful trigeminal neuropathy with persistent background facial pain severity > 5/10 on VAS
• Experience pain with a score of greater than 5 on a 0-10 scale (VAS) in the previous 24 hours before procedural treatment and at the time of procedural treatment.
• Eligible for trigeminal nerve block procedure and have not had a trigeminal nerve block procedure for pain management prior to the enrollment in the current study.
• Able to provide informed consent.

Exclusion Criteria:

• Presence of a significant structural lesion (e.g., tumor) as the cause of pain as shown in at least one neuroimaging study.
• Current diagnosis of fibromyalgia, temporomandibular disorders (TMD), odontogenic pain or other orofacial pain deemed unrelated to the trigeminal nerve as the origin.
• Allergy or any other hypersensitivity reactions to guanfacine or lidocaine or local anesthetic of the amide type, or to both iodinated contrast and gadolinium contrast.
• Females who are pregnant or breastfeeding and/or plan to become pregnant or to breastfeed during study participation.
• Participation in another investigational drug study within 30 days before randomization.
• Inability to understand the requirements of the study, inability to abide by the study restrictions, inability to fill out the questionnaires, or inability to return for the required treatments.
• Any clinically significant medical or surgical condition that in the investigator's opinion could interfere with the administration of study drug, interpretation of study results, or compromise the safety or well-being of the subject (i.e. infection, unable to stop anticoagulants).
• No reliable access to telephone service to allow for contact with study personnel.