Pharmaceutical companies continue to invest millions and millions of dollars into MS research in an effort to better understand the condition and ultimately develop safer and more effective treatments. Indeed more experimental treatments for MS are currently progressing through the latter stages of clinical development than ever before. However, the focus of this article is not on one of these experimental treatments, but instead on a drug that has been available for many years, although not for the treatment of MS.
The drug in question is naltrexone. It has been available since the early 1990s and is principally used for the management of opioid (e.g. heroin) and alcohol addictions. Its effects in MS were first noticed in the 1980s by Bernard Bihari, a New York neurologist, who discovered that low doses of naltrexone appeared to relieve the symptoms of a wide range of conditions, including cancer, AIDS and MS. For the treatment of MS it is believed that naltrexone should be used at much lower doses than for the treatment of addiction (typically 10 – 50 times lower dose) – hence the therapy is referred to as ‘low dose naltrexone’ therapy or LDN.
Naltrexone has never been clinically tested to the high standards required for it to be licensed for use in MS patients. That said, a growing body of anecdotal evidence (mostly from MS patients in the USA who take the drug) suggests that low doses of naltrexone actually may provide effective symptom relief in some MS patients. LDN therapy has been used relatively widely in the USA but it is also beginning to attract more attention in the UK – although not from the pharmaceutical companies, instead from the very active patient community through various websites and internet forums. Advocates for its use cite anecdotal evidence from over 16,000 users in the USA and argue that
LDN has a 98% record at preventing further MS progression, with many users experiencing considerable improvements in their condition, often within days or weeks of beginning the treatment. Clearly these are very positive claims, however it should be pointed out that these are largely based on anecdotal evidence and NO rigorous clinical trials have been performed verifying naltrexone’s benefits in MS patients.
However in an effort to better understand naltrexone’s purported benefits, various private clinics and academic institutions have performed a number of small pilot studies in MS patients. The results are mixed and the most recent trials are summarised below;
In 2006, in Germany, a short study in 60 people with progressive MS showed that after a 10-day treatment period, 10 of the 30 people in the treatment group showed some improvement in symptoms as did 5 people in the placebo group.
In Italy, an open-label 6-month study in 40 people with primary progressive MS (published in 2008) demonstrated that LDN was safe and well-tolerated. The results also indicated that there was a significant reduction in spasticity at the end of the trial, but no significant changes to measures of fatigue, depression or quality of life. Five patients dropped out of the study.
In the USA, a study conducted by the University of California in San Francisco (UCSF) in 80 people with MS (published in 2008) showed that LDN significantly improved quality of life (specifically mental health, pain, and self-reported cognitive function) as measured by the MS Quality of Life Inventory. However, there was no impact on symptoms such as fatigue, bowel and bladder control, sexual satisfaction, and visual function. Vivid dreaming was reported during the first week of treatment, but no other adverse effects were reported.
Also in the USA, the MindBrain Consortium in Akron, Ohio recently started a 16-week, double-blind, randomised, placebo-controlled, crossover study of LDN in 36 people with either progressive or relapsing-remitting MS. The study is examining symptom severity, changes in quality of life and sleep patterns.
These small pilot studies are very welcome and suggest that further research is warranted. However, much larger and more robust clinical trials are required before any regulatory body can ‘approve’ or license naltrexone for use in MS patients. Until such approval is granted any doctor who prescribes naltrexone for MS will be doing so ‘off-label’. (Off-label prescribing is a process whereby a doctor prescribes a drug for conditions other than that for which it has been tested and approved, if the doctor feels that it will benefit the patient. Naltrexone is licensed in the UK for the treatment of addiction (not MS) therefore if it was prescribed to an MS patient the doctor would have prescribed it ‘off-label’. Drugs prescribed off-label are the direct responsibility of the prescribing doctor, who will therefore need to be convinced that the treatment is safe and potentially effective. Positive results from large, double-blind, placebo controlled phase III trials are usually required before a doctor will consider prescribing a drug ‘off-label’). In most cases the trials outlined above would not be considered sufficient evidence of an effect in MS patients. Unless positive results from such a clinical trial become available it is unlikely that doctors or specialists in the UK will advocate the use of naltrexone in MS patients.
Unfortunately it is unlikely that any major pharmaceutical company will commit the resources required to complete the clinical trials needed to approve naltrexone for use in MS. The reality is that as naltrexone is an older drug and no longer patent-protected, it would be unprofitable for any pharmaceutical company to invest in its development. Fortunately however when this situation arises various charitable organisations, research institutes or government bodies sometimes step in. In this case, a group called the ‘LDN Research Trust’ has been established with the goal of raising enough money to fund a specific clinical trial on low dose naltrexone therapy in MS patients (http://www.ldnresearchtrust.org). The group also helps patients obtain LDN from their GP or neurologist, either on the NHS or through private prescription. By setting up and running such a clinical trial, the Trust hopes to better qualify the current evidence base and ultimately prove the safety and efficacy of LDN therapy in MS patients. Even with a favourable outcome such a trial would be very unlikely to result in naltrexone being licensed for use in MS, however, a positive trial would go some way towards convincing the medical community as to any benefits, potentially leading to improved access to the drug through more off-label prescribing.
To summarise, naltrexone has been available for many years for the management of opiate and alcohol addiction. Following Dr Bihari’s research in the 1980s it has been sporadically studied as a potential treatment for MS, fuelling considerable patient interest and a growing body of anecdotal evidence in support of its beneficial effects in MS patients. However, from an evidence-based, clinical perspective there is currently insufficient data from any robust clinical trial programme to prove that the drug actually does benefit MS patients. Until such trials are conducted and/or more clinical data becomes available it is unlikely that UK doctors will be willing to prescribe low dose naltrexone therapy to MS patients.
Action MS would ask any patient interested in low dose naltrexone therapy to contact their GP or neurologist for further information.
To contact the author about this article please email Simon at firstname.lastname@example.org