Abstract
AD Macleod, Consultant Psychiatrist, Psychiatric Consultation Service, Christchurch Hospital, Christchurch, New Zealand; SG Duffy, Consultant Psychiatrist, Community Alcohol and Drug Service, Christchurch, New Zealand:
High rates of comorbidity suggests that posttraumatic stress disorder (PTSD) and substance use disorders are functionally related to one another [1]. There is emerging consensus that PTSD encourages self-medication and that substance withdrawal amplifies PTSD symptoms [1, 2]. Heroin and alcohol may dampen intrusive and hyperarousal PTSD symptoms [2]. Opioid dysregulation is a feature of PTSD [3]. Posttraumatic stress disorder has been conceptualized as both opioid deficient and opioid excess states [3].
Opioid dependant persons recruited onto methadone maintenance programmes frequently complain about the choice of opioid.
A 28-year-old woman maintained on methadone 70 mg/day (with high ‘therapeutic’ serum levels) complained of the exacerbation of previously quiescent intrusive and hyperarousal symptoms of chronic PTSD (childhood sexual and physical abuse). About one year previously the perpetrator of her abuse had been diagnosed with terminal malignancy and the patient had resorted to re-using illicit morphine ‘to control my posttraumatic symptoms’. At relapse, affective symptoms were not prominent. Benzodiazepines failed to suppress her night terrors and hypervigilance. Medicinal maintenance morphine (200 mg sustained release b.i.d.) resulted in a rapid clinical stabilization which has been sustained for nearly three years.
Methadone possesses antagonistic action of the glutamate receptor NMDA [4], whereas morphine does not. The glutamatergic system is a psycho-biological pathway conceptually implicated in PTSD [3]. Methadone is a pure mu receptor antagonist, devoid of morphine kappa receptor action. The endogenous opioids involved in the human stress response are active at the mu receptors. Therefore, methadone may not be the ideal maintenance opioid for persons with PTSD and substance abuse.