Naltrexone is a name you might have heard before. Mainly because it almost sounds similar to the infamous opioid blocker, naloxone, which is the active ingredient found in the popular medication Narcan ® used for opioid overdose. However, naltrexone is a bit different from naloxone since it has a greater bioavailability and a longer half-life. Basically meaning there are more molecules available for its target cells and it stays in the body a little longer than naloxone.
Naltrexone alone is used to prevent relapse with opioid dependence and for maintenance treatment for alcohol dependence. The typical commercially available dosage of naltrexone is 50 to 100mg daily and it is also found in combination with bupropion (Contrave®) for weight loss. However, naltrexone can come in a lower dose as well. Low dose naltrexone (LDN) is usually 4.5mg and this is one-tenth of the typical dose treatment for opioid addiction but has powerful uses. In its lower strength, naltrexone has both analgesic and anti-inflammatory effects which are not typically seen in the higher doses, therefore it can be used in many different conditions such as, chronic pain and other inflammatory diseases.
What can it do for chronic pain?
According to the CDC, in 2019, 20.4% of adults suffer from chronic pain and 7.4% of adults had chronic pain that limited life or work activities. Chronic pain can be debilitating to the person if not adequately treated. When it comes to pain, there has been evidence that LDN can help treat fibromyalgia.
Fibromyalgia stems from nerves and patients will typically experience a more than usual enhancement of different stimuli such as heat, cold and pain. This occurs by certain cells called glial cells in the spinal cord becoming activated and releasing different molecules that cause inflammation (proinflammatory), such as, reactive oxygen species (ROS), ATP and excitatory amino acids which all further builds up transmission of pain signals and results in an extreme pain response. This overstimulated pain further leads to fatigue, cognitive impairment and sleep difficulty. A study that showed thirty women with fibromyalgia concluded that about 57% of the participants had significant reduction of pain while taking LDN. Therefore leading to LDN being a possible treatment for this population of patients.
What can LDN do for other conditions?
LDN can also have beneficial effects on other inflammatory conditions, such as, Crohn’s Disease (CD) and multiple sclerosis (MS). CD is a type of inflammatory bowel disease (IBD) that causes inflammation and pain in the mainly in the gastrointestinal tract but also in other parts of the body as well. LDN has been shown to reduce both self-reported pain and markers of inflammation resulting in overall patient improvement. MS is another type of inflammatory condition in which the protective covering (myelin sheath) that surrounds the nerve fibers of the brain, optic nerve and spinal cord, are damaged causing slow nerve impulses and other debilitating neurological problems. LDN has shown to help reduce spasticity and some improved mental health of patients with MS.
How does LDN work?
While the full mechanism of LDN is unknown, we do know that it works on chronic pain and other inflammatory conditions by suppressing the effects of proinflammatory molecules of the nervous system, thus reducing the symptoms these patients frequently experience. The usual dosage for LDN is 4.5mg once daily at bedtime and treatment generally lasts for 6 weeks in order to see the benefits. Furthermore, it is not known why a low dose would be beneficial over the usual doses for naltrexone. It is theorized that lower doses would actually help to treat chronic conditions more effectively than the higher strengths since the higher ones would completely block the targeted receptors and might make it worse.
What are the benefits of LDN?
There are quite a few benefits for using LDN:
- Low cost. Naltrexone is a generic medication therefore it is relatively inexpensive. However, this is a medication that needs to be compounded since this strength is not available through manufacturers like the higher strengths.
- Low side effects. Side effects of LDN are generally mild. If anything, vivid dreams might be experienced in the first few doses, but then will lessen over time.
- No known abuse potential. Since the normal naltrexone doses are used as an opioid blocker and used for substance abuse, the lower doses are better since there is no misuse or abuse reported.
What are the disadvantages of LDN?
With benefits there are a few drawbacks of LDN:
- Lack of proper experimental findings. LDN is more of an alternate method for treating inflammatory conditions and there are studies but no hard evidence-based trials therefore making it hard for doctors to prescribe LDN. Especially in regards to dosing and safety aspects.
- Not recognized by insurance companies. Because LDN has to be compounded and is not commercially available through a manufacturer, many insurance companies will not pay for this particular dose. Therefore patients will have to find a compounding pharmacy and pay their usual rate for this medication.
Although larger clinical trials of LDN are needed to be done to understand the full benefits of this medication, overall this is a very promising treatment for a variety of conditions, especially in the case of chronic pain. If you or someone you know wants to learn more about LDN consult with your doctor to see if this is the best treatment option for you.
References:
- Younger, J., Parkitny, L., & McLain, D. (2014). The use of low-dose naltrexone (LDN) as a novel anti-inflammatory treatment for chronic pain. Clinical rheumatology, 33(4), 451–459. https://doi.org/10.1007/s10067-014-2517-2
- Bradley L. A. (2009). Pathophysiology of fibromyalgia. The American journal of medicine, 122(12 Suppl), S22–S30. https://doi.org/10.1016/j.amjmed.2009.09.008
- Younger, J., & Mackey, S. (2009). Fibromyalgia symptoms are reduced by low-dose naltrexone: a pilot study. Pain medicine (Malden, Mass.), 10(4), 663–672. https://doi.org/10.1111/j.1526-4637.2009.00613.x
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