A Comparative Study of the Efficacy of Venlafaxine and Naltrexone for Relapse Prevention in Patients With Opioid Use Disorder Attributed to Tramadol

Introduction Venlafaxine is a nontricyclic antidepressant that selectively inhibits serotonin reuptake at low doses, but at higher doses, it blocks neuronal reuptake of serotonin, norepinephrine, and, to a lesser degree, dopamine (Debonnel et al., 2007).

Venlafaxine was also proved to have analgesic and antinociceptive effects through opioid mechanisms (Markowitz & Patrick, 1998; Schreiber et al., 1999; Schreiber et al., 2002).

In the study of McDowell et al. (2000), venlafaxine was successfully used to treat patients with cocaine dependence comorbid with major depression. In animal studies, venlafaxine demonstrated effectiveness to attenuate morphine withdrawal symptoms (Lu et al., 2001) and attenuate acquisition of intravenous self-administration of heroin in rats (Magalas et al., 2005). Lin et al. (2008) found that venlafaxine is effective in alleviating withdrawal symptoms of heroin with good tolerability and safety.

Lofixidine works by blocking the release of norepinephrine, a hormone similar to adrenaline that contributes to opioid withdrawal symptoms. Lofexidine is a non-opioid prescription medicine used in adults to help with the symptoms of opioid withdrawal that may happen when you stop taking an opioid suddenly.

Naltrexone, is an opioid antagonist, without abuse liability and the oral formulation was found to be a safe option for motivated individuals who prefer not to be treated with opioid agonist medication or where opioid agonist medications are not legally available (Krupitsky et al., 2010, Ling et al., 2012, Mooney, 2016). Although oral naltrexone had a limited side effect profile, the clinical evidence demonstrating its efficacy for the treatment of opioid use disorder has revealed limitations in its use, particularly as it requires detoxification and a several days period of opioid abstinence prior to initiation (Ling et al., 2012, Nunes et al., 2015, Mooney, 2016).