Neuropathic pain is difficult to treat, and the available options are often inadequate.
Ambroxol
hydrochloride is a metabolite of BROMHEXINE that stimulates mucociliary action
and clears the air passages in the respiratory tract. Tropical ambroxol
provided a significant change in pain associated with neuropathy although the
clinical future prospects are yet to be inferred.
Neuropathic pain
is difficult to treat, and the available options are often inadequate. The
expectorant ambroxol also acts as a strong local anaesthetic and blocks sodium
channels about 40 times more potently than lidocaine. It preferentially
inhibits the channel subtype Nav 1.8, which is expressed especially in
nociceptive C-fibres. In view of the low toxicity of ambroxol, it seemed
reasonable to try using it for the treatment of neuropathic pain that failed to
respond to other standard options.
The medical
records of seven patients with severe neuropathic pain and pain reduction
following topical ambroxol treatment are reported retrospectively. As standard
therapies had not proved sufficient, a topical ambroxol 20 % cream was
repeatedly applied by the patients in the area of neuropathic pain.
The reasons for
neuropathic pain were postherpetic neuralgia (2 ×), mononeuropathy multiplex,
phantom pain, deafferentation pain, postoperative neuralgia and foot neuropathy
of unknown origin. The individual mean pain intensity reported was between 4
and 6/10 (NRS), maximum pain at 6-10/10 (NRS). The pain reduction achieved
individually following ambroxol cream was 2-8 points (NRS) within 5-30 min and
lasted for 3-8 h. Pain attacks were reduced in all five patients presenting
with this problem. Four patients with no improvement after lidocaine 5 % and one
patient with no response to capsaicin 8 % nevertheless experienced a pain
reduction with topical ambroxol. No patient reported any side effects or skin
changes during a treatment that has since been continued for up to 4 years.
Ambroxol acts as
a strong local anaesthetic and preferentially inhibits the nociceptively
relevant sodium channel subtype Nav 1.8. For the first time, we report below on
a relevant pain relief following topical ambroxol 20 % cream in patients with
neuropathic pain. In view of the positive side effect profile, the clinical
benefit in patients with pain should be investigated further.
Schmerz. 2015 Dec
Topical ambroxol for the treatment of neuropathic pain: An initial clinical observation.
Kern KU et al.
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