Naltrexone or Vivitrol in the OutPatient Treatment Setting for Opiate Dependence?


About half of the individuals that come into our treatment center at M.I.A. are familiar with the pharmaceutical Naltrexone. Individuals that are not familiar with Naltrexone often confuse it with the Dopamine agonist Buprenorphine, the active ingredient in Subutex and Suboxone. I want to take this time to clarify a few points; and basically leave the reader with the information necessary to make an informed decision as to whether or not they think this could prove beneficial in their own recovery.

First, let's look at what opiates and opiodes do in our bodies. Opiates are agonists for the neurotransmitter dopamine; this means that they enter the body and can act in the same way as dopamine on post-synaptic neuron receptor sites to cause action potentials. With excessive amounts of dopamine agonists administered through chronic use, an increase in the density of post-synaptic neuron receptor sites occurs. While this has minimal effects during usage, the body is unable to function when dopamine or dopamine/agonist levels fall. When this occurs action potentials can not occur at optimal levels and we see both physical withdrawal symptoms, as well as a decrease in cognitive functioning.

To deal with the problem of excessive receptor site density Buprenorphine (also an agonist for Dopamine) is used to allow action potentials to occur. Buprenorphine does not activate the site as strongly as an opiate but enough to minimize withdrawal symptoms and allow for normal functioning. However, ceasing Buprenorphine use will also result in withdrawal as this too is considered addictive.

Naltrexone (the active ingredient in the Vivitrol (R) injection) acts as an antagonist for dopamine. This molecule acts the opposite of the neurotransmitter in that while it also binds to the receptor site it does not cause an action potential to occur. Naltrexone also has a higher affinity than that of the most commonly used opiates so that if both are in the system Naltrexone will bind before the latter. This does two things for the patient utilizing this pharmacological therapy. 1) Cravings associated with decreased amounts of available dopamine/agonists is controlled. 2) Dopamine agonists with lower affinities than that of Naltrexone cannot bind to receptor sites. This means that opiates commonly used by those struggling with addiction will not work while using Naltrexone, and because these sites are not being activated normal density will return; something that cannot occur on Buprenorphine or Methadone.

Simply stated, Naltrexone acts as a cast for our brains throughout the healing process...www.midwestinstituteforaddiction.org