effect of guanfacine on the reversal of opioid-induced hyperalgesia (oih)

Conditions: Chronic Pain

Summary: combination of guanfacine with opioid medication as a standard treatment for chronic pain.

this aim proposes that guanfacine would be a useful drug to reverse opioid-induced hyperalgesia (oih) when combined with opioids in chronic pain management.

Eligibility criteria:
inclusion criteria * 18-65 years old * chronic neck or back pain condition for at least 6 months * vas score of 4-8, despite opioid therapy * on a stable morphine equivalent dose of at least 60mg/day and ≤ 240mg/day for at least 3 months exclusion criteria * has taken methadone, suboxone, fentanyl, and/or tramadol in the last six (6) months * has taken guanfacine (or other alpha-2ar agonists) in the last six (6) months * changes to current or adding new pain treatment while enrolled in the study (i.e. opiates, epidural steroid injection) will be reviewed by the study physician * unable to independently provide informed written consent * sensory deficits at site of qst, such as peripheral neuropathy * intolerable allergies or has had a severe adverse reaction to study medication (i.e. guanfacine, lactose, vitamin b2 a.k.a. riboflavin) * takes vitamin b2 \> 1.6mg/day during the study * pregnant or breastfeeding * pending litigation related to neck or back pain * diagnosed with raynaud's syndrome * has other chronic pain conditions such as fibromyalgia or joint osteoarthritis that are predominant over back and neck pain with regard to its intensity (vas) * has known pre-existing severe cardiovascular disease (i.e. arrhythmia - prolonged qt interval \> 440ms), cerebrovascular disease/accident (i.e., stroke), hepatic or renal impairment, cns condition, metabolic condition, or history of syncope * hypotension (sbp \< 90 mmhg and dbp \< 60 mmhg for female or sbp \< 100 mmhg and dbp \< 60 mmhg for male; measured while in a sitting position) will be reviewed by a study physician * bradycardia (resting heart rate \< 60 bpm) will be reviewed by a study physician * subjects are on antihypertensive drugs (e.g., a beta-blocker) that result in hypotension and/or bradycardia as defined above * tests positive for illicit drugs, marijuana, or non-prescribed drugs * major psychiatric disorders that required hospitalization in the past 6 months such as: major depression, bipolar disorder, schizophrenia, anxiety disorder, or psychotic disorders * currently in a treatment program for alcohol or drug abuse, or currently on methadone or buprenorphine (i.e. suboxone, subutex) for treatment of addiction, or currently prescribed stimulants for treatment of adhd * history of substance or alcohol abuse (meets dsm iv criteria) per medical record or subject admission * subjects are on medications that serve as cyp3a4/5 inhibitors or cyp3a4 inducers including, but are not limited to, valproic acid, macrolide antibiotics, antifungal drugs, st. john wort, ace inhibitors, nefazodone (antidepressant), calcium channel blockers, h2-receptor antagonists, anti-hiv or aids drugs, and antiepileptic drugs * subjects are on medications that are ligands for alpha2-adrenergic receptors including antipsychotic drugs (e.g. clozapine) and tricyclic or tetracyclic antidepressants (e.g. imipramine, mirtazapine, mianserin). any medications taken by a subject at the enrollment will be reviewed regarding their compatibility with guanfacine as well as possible confounding side effects. subjects will be allowed to take non-opioid pain medications except for gabapentinoids and amitriptyline/nortriptyline as far as such medications do not have incompatibility with guanfacine.

Keywords: pain pain management neck back