Ambroxol is a drug that breaks up phlegm. As such it is used in medicines for the treatment of conditions which result in airway congestion such as asthma, bronchitis, coughs and colds. More recently, however, studies have shown that it may also be an effective drug for the treatment of the symptoms of neuropathic pain.
In a 2018 study, eight patients who had suffered Complex Regional Pain Syndrome (CRPS) for less than 12 months were treated with ambroxol as a topical cream in a concentration of 20%. The researchers found that “Following treatment we found a reduction of spontaneous pain (6 patients), pain on movement (6 patients), edema (seven patients), allodynia (six patients), hyperalgesia (seven patients), reduction of skin reddening (four patients), improvement of motor dysfunction (six patients) and improvement of skin temperature (four patients).”
Unsurprisingly, this led them to conclude that “Topical treatment with ambroxol cream may ameliorate symptoms of CRPS.”
2017 saw the publication of two studies into the effect of ambroxol on the symptoms of Fibromyalgia.
The first study involved 25 patients taking ambroxol orally, three times a day for a month. This was a very small-scale, short-term pilot study and researchers warned additionally that the open nature of the study did not allow them to rule out the possible role of the placebo effect in the results. However, the drug was said to be “well tolerated” and “side effects were minor”. The conclusion was that “the use of ambroxol was associated to decreased fibromyalgia pain and improved fibromyalgia symptoms.”
In the second study, which was entitled “Ambroxol for the treatment of fibromyalgia: science or fiction?”, the authors concluded that “fibromyalgia treatment with ambroxol should be systematically investigated, since this compound is the only treatment option used thus far that has the potential to address not just individual but all of the aforementioned aspects of pain.”
That’s quite a statement! However, they were swift to stress that it’s still early days and that “at this point, the evidence base for ambroxol is currently not strong enough for clinical recommendation.”
January 2019 saw the publication of another small-scale study involving the use of ambroxol as a topical cream. This time, “clinically significant pain relief” was seen within 15 to 30 minutes in patients suffering Trigeminal Neuralgia who applied the cream following a pain flare. Pain relief was said to last between 4 and 6 hours and “in one case pain was eliminated after 1 week.”
In fact, so impressed were the researchers that they concluded “In view of the positive side effect profile, topical ambroxol for patients with such a highly impaired quality of life should be investigated further as a matter of urgency.”
How does ambroxol work?
It is thought that ambroxol’s analgesic properties arise from its action as a potent sodium and calcium channel blocker. It is these channels within the peripheral nervous system that carry pain signals. Other studies also note its anti-inflammatory properties.
Clearly, researchers in all of the small-scale studies published so far believe that ambroxol shows real promise as a treatment for the symptoms of a variety of types of neuropathic pain. However, the reality is that the current absence of large-scale clinical trials means that it is years from reaching the market. This is a huge shame because, as far as can be determined currently, unlike so many other drugs used in the treatment of neuropathic pain, ambroxol seems to be both non-addictive and to have very few side-effects. An added benefit is that, in certain situations, it can be applied topically.
Fortunately, at the very least there does seem to be a desire among the research community to push forward with larger-scale studies. Unfortunately, as with so many other promising treatments and therapies for chronic pain, it is yet another example of ‘watch this space’!