In this answer, you're going to see some of the same arguments and tactics as you see from those pushing DCA as a potential cure for cancer.
This is mainly because this particular line of treatment may yield some legitimate benefits for a variety of related conditions, but has not yet been been appropriately tested, even though studies are underway (as I'll show later).
Simply put, until the data is in, there is no reason to think that Low-Dose-Naltrexone is a miracle cure for anything, or that there is some conspiracy to keep evidence from coming to light. Steve Novella and PZ Myers take a good look at this issue in both neurologicablog, and pharyngula it's with regard to DCA and cancer, but they address the issue of jumping the gun before the research is in and the "big pharma is covering this up" aspect of the argument, which is essentially the same here.
What is Naltrexone?
Naltrexone is an opiate antagonist. Essentially what it does is block the receptors in the body which opiate drugs (heroin, morphine, oxycontin) would bind to in order to stop them from having an effect. It is most often used clinically to treat opiate dependence, and occasionally alcoholism. It is also sometimes used in emergency detoxification from opiate overdoses, but only in a hospital setting.
Instructions for patients regarding its use can be found here, including why it is typically prescribed, what the dangers are, and what to consult with your physician about.
Reasons to be skeptical of this claim
Any time you see a claim that a variety of conditions such as this can be affected by one drug or therapy, there is reason to be skeptical.
Also, just because something is FDA approved for one condition does not automatically make it safe or even reasonable for other conditions. For example, radiation therapy is FDA approved to treat certain cancers, but that does not mean it should be used to treat the common cold.
Skepticism is especially warranted when you see arguments like this:
(which is literally the same argument made for the big pharma suppression of DCA for cancer.)
As for the claim that it has "no side effects", this is just a general point to apply any time one is skeptically evaluating medical claims:
If anyone says that a medication has no side effects, that person is either lying or horribly misinformed. Every medication has side effects.
Clearly naltrexone has side effects, and some are mentioned at the link provided in your question. Although they aren't particularly focused on, presumably this is because the dosage rates they are reccommending haven't been studied enough yet to know what those side effects would be.
Also, naltrexone is NOT without patent protection and in fact, patents seem to be held for the compound in several forms and this statement seems to be included mostly to drum up support for research into using Low-Dose-Naltrexone (LDN) for the variety of conditions mentioned. However the fact that this can be disproved with a simple web search can cause the claim to lose credibility, regardless of the science.
Claims like this call for skepticism, but one incorrect aspect of the argument does not necessarily mean that all of the information is incorrect. Here we have to especially careful to separate the science from the "conspiracy" elements of the claim, and evaluate the science on its own merit while not allowing ourselves to be swayed by the supposed conspiracy.
What is the mechanism of action for Low-Dose-Naltrexone?
The proposed mechanism by which LDN therapy is theorized to work is a little complex, and is explained by its proponents here:
In order to understand how LDN works,
it is crucial to briefly introduce the
workings of the ‘natural opioid’
Endorphins are opiate-like molecules
produced naturally in the body. The
term ‘endorphin’ comes from
‘endogenous morphine’, meaning that it
is created within the body, and
differentiating it from opioids that
are administered from external
Endorphins are produced in most cells
in the body, and are important
regulators of cell growth and
therefore the immune system. Disorders
of the immune system can occur with
unusually low levels of these
endorphins. The particular endorphin
that has been found to influence cell
growth as well as immunity is called
Opioid Growth Factor (OGF) or
For an endorphin such as OGF to exert
its beneficial effects, it must
interact with the body’s cells. It
does this by binding to a receptor on
the surface of the cells. The receptor
to which OGF binds is the ‘Opioid
Growth Factor Receptor’ (OGFr) –
previously known as the Zeta (ζ)
Thus, for the endorphin system to be
fully functional, two elements are
required: opioid production and cell
Naltrexone is an externally
administered drug that binds to opioid
receptors. In doing so, it displaces
the endorphins which were previously
bound to the receptors. Specifically,
by binding to the OGF receptor, it
displaces the body’s naturally
As a consequence of this displacement,
the affected cells become deficient in
OGF and three things happen:
1.Receptor production is increased, in order to try to capture more OGF.
2.Receptor sensitivity is increased, also to try to capture more OGF.
3.Production of OGF is increased, in order to compensate for the perceived
shortage of OGF. Since LDN blocks the
OGF receptors only for a few hours
before it is naturally excreted, what
results is a rebound effect; in which
both the production and utilization of
OGF is greatly increased. Once the LDN
has been metabolized, the elevated
endorphins produced as a result of the
rebound effect can now interact with
the more-sensitive and more-plentiful
receptors and assist in regulating
cell growth and immunity.
The duration of the rebound effect
varies from individual to individual,
but generally persists for about one
The benefits of the rebound effect can
only be utilized by taking a low dose
of regular naltrexone. Taking a high
dose of naltrexone or using a
timed-release formulation will result
in continuous blockade of OGF
receptors, and the rebound effect will
not serve any useful purpose.
In scientific terminology, the use of
regular-dose naltrexone results in
‘continuous opioid receptor blockade’
whilst the use of LDN results in
‘intermittent opioid receptor
blockade’. In order to benefit from
the rebound effect and achieve the
therapeutic benefit of LDN, it is
essential to avoid timed-release
versions of naltrexone.
Individuals vary in their metabolic
speed and this will result in
inter-patient variation in the speed
at which LDN is eliminated from the
body, as well as the length of the
rebound effect. Whilst a single daily
dose of between 3mg and 5mg will be
suitable for most patients, individual
modification of dose or frequency is
This explanation remains theoretical and controversial, although it is currently being studied.
Low-dose Naltrexone is currently being studied for :
Squamous cell carcinoma of the head and neck - preliminary study, shows potential as novel treatment.
Human ovarian cancer (in mice) - preliminary, indicates native opiate pathway may suppress human ovarian cancer in mice.
Multiple Sclerosis (MS) - Study on mice with experimental autoimmune encephalomyelitis (EAE, an animal model used to study MS in the laboratory) indicates LDN therapy is non-toxic to patients, did not exacerbate symptoms, but also may have positive effects.
Amylotrphic Lateral Sclerosis (ALS) - currently being studied but as of now, I find the data unavailable
Crohn's Disease - treatment of at least one pediatric patient was attempted, however the data is unavailable at this time.
- A larger study of crohn's patients
can be found here. Preliminary
findings indicate mucosal healing.
LDN has been studied with regard to Fibromyalgia as well, but I am not going to consider those trials, mostly due to the fact that fibromyalgia itself remains controversial.
The data from the AIDS study is still unavailable.
Right now, Low-Dose-Naltrexone shows some promise in a few conditions. However, the research is still quite preliminary, and likely will not be in for years. However, until its mechanism of action, and potential side effects have been better studied, LDN will be ripe for colonization by woo and there will likely be those who will claim it to be a cure for everything from athlete's foot to xenophobia, because "they haven't proven it's not". It will also probably fall victim to the general public's lack of knowledge of how the research process works, and will probably be sensationalized by the media more than once.
Basically, it seems that some are jumping on the LDN bandwagon a little prematurely.