What Is Naltrexone?
Naltrexone is a medication that acts as a competitive antagonist to the mu opioid receptors in the body. These receptors are found all over the body, especially in the brain and the gut. The opiate molecules (endorphines) our body's naturally make attach to these receptors. Opium, heroin, morphine, and the other opiates, including Suboxone, attach to these receptors also.
Competitive antagonist simply means that for these specific receptors, the naltrexone goes into the spot where an opiate normally would and it directly blocks the opiates from attaching there. The naltrexone has a greater affinity for the receptor site than all other opiates, ie. it holds on tighter. If there's an opiate there, it will kick it out and occupy the spot. When this happens, withdrawals happen. These are called precipitated withdrawals and they are intense! This can be avoided but it's one of the reasons someone who understands this body chemistry well should be administering the Vivitrol shot.
Why Naltrexone For Opiate Dependence?
Since naltrexone blocks opiates from binding the the mu receptors, once the the naltrexone is there, you essentially can't get high from opiates anymore. Naltrexone is essentially a really effective security blanket to opiate relapse. For most people, physical craving is usually diminished with naltrexone as well.
Why Naltrexone For Alcohol Dependence?
Naltrexone has a couple of useful effects in alcohol use disorder. One is that for most people, it significantly reduces or eliminates craving. This helps reduce relapse. Secondly, if you do drink alcohol, you don't get sick like with the medication Antabuse, but it is not the same experience. Drinking alcohol on naltrexone takes out the pleasurable feeling and makes it much less enticing in this way also.
What Is The Naltrexone Pellet?
The pellet is naltrexone made into a sterile, large vitamin-sized pellet, by a compounding pharmacy. The pellet is inserted in the subcutanoues tissue (in the fat), typically around the navel or waistline. The pellet then dissolves over a 2 month time period, keeping naltrexone in the bloodstream the entire time.
Why The Naltrexone Pellet And Not Pills?
That's easy. You can choose to not take a pill. I can't tell you how many times I've had people refuse Vivitrol and take naltrexone pills daily, only to relapse weeks or months later because life got stressful and they decided not to take their medication because whether consciously or subconsciously, they wanted to get high or drink.
Naltrexone Pellet OR Vivitrol?
There are handful of factors to consider here.
1. If you're paying out of pocket, the pellet and procedure are going to be less than half the cost of paying for Vivitrol.
2. The pellet is not covered by insurance and Vivitrol typically is.
3. There is a small incision with a few stitches so there's usually a small scar. If you do treatment for a year, which is recommended, that's 6 different incisions.
4. The pellet is ideal immediately after detoxing from opiates. Vivitrol prescriptions take a bit to go through the system and this doesn't work out if you need "protection" using naltrexone now. In this scenario, I will often recommend a pellet and then start with Vivitrol each month after that.
5. The pellet lasts 2 months. Vivitrol lasts one.
6. The pellet can be removed if needed for something like a medical emergency or surgery. Vivitrol isn't removable once it's injected.
What are Naltrexone Pellet Side Effects?
There are two primary considerations for you and your practitioner to take with regard to naltrexone in general. In a small portion of individuals, the medication is hard on the liver and liver enzymes will go up. Sometimes the liver enzymes are high already from substance use or an infection like Hepatitis C. In these cases, I personally still use it and the liver enzymes come down after the substance is removed or the infection is treated.
As a personal anecdote, I've treated literally hundreds of patients with long-acting naltrexone and never had anyone's liver enzymes go up. It's something to be aware of and also of little concern to me at this point in my career.
The second consideration, which is not exactly a side effect, is in opiate relapse while under naltrexone treatment. As mentioned before, using opiates will have no effect essentially. At least not the desired ones. If someone decided to take enough opiates to try and overcome the Vivitrol shot and get high, they'd most likely overdose before or at the point where that could happen. NEVER TRY THIS!
With any procedure, infection and bleeding are inherent risks. This doesn't need to be an issue however as there are no major vessels near the implantation site and using sterile technique should avoid infection. Periodically, but quite infrequently, an inflammatory reaction happens around the pellet, which is self limiting in the majority of cases.
Is The Naltrexone Pellet FDA Approved?
While these have been used successfully and safely for many years, they are not currently FDA approved.