[Topical ambroxol for the treatment of neuropathic pain: A first clinical observation. German version].

Abstract

BACKGROUND:

Neuropathic pain is difficult to treat and available options are frequently not sufficient. The expectorant ambroxol also works as a strong local anesthetic and blocks sodium channels about 40 times more potently than lidocaine. Ambroxol preferentially inhibits the channel subtype Nav 1.8, which is expressed particularly in nociceptive C fibers. Due to the low toxicity, topical ambroxol seemed to represent a reasonable therapeutic attempt for treatment of neuropathic pain resistant to other standard options.

MATERIALS AND METHODS:

Medical records of 7 patients with severe neuropathic pain, in whom many attempts at treatment with approved substances were not sufficient or possible, are reported retrospectively. Patients were then treated with topical ambroxol 20% cream applied in the area of neuropathic pain.

RESULTS:

Causes of neuropathic pain were postherpetic neuralgia (2-×), mononeuropathy multiplex, phantom pain, deafferentation pain, postoperative neuralgia and an unclear allodynia of the foot. Mean pain intensity was reported as 4-6/10 on a numeric rating scale (NRS) and maximum pain intensity as 6-10/10. Pain reduction following ambroxol cream was 2-8 points (NRS) within 15-30 min and lasted 3-8 h. Pain attacks were reduced in all 5 patients presenting this problem. Topical ambroxol achieved pain reduction in 4 patients with no improvement after lidocaine 5% and 1 patient with no response to capsaicin 8%. No adverse events or skin changes have been observed, and the longest treatment duration is currently 4 years.

CONCLUSION:

Ambroxol acts as a strong local anesthetic and preferentially inhibits the nociceptive-relevant sodium channel subtype Nav 1.8. For the first time, we report relevant pain reduction following topical Ambroxol 20% cream in patients with neuropathic pain. Regarding the advantageous profile with rare side effects, the clinical benefit for pain patients should be further investigated.

• Authors: K-U Kern, T Weiser
• Journal: Schmerz (Berlin, Germany) (Schmerz) Vol. 29 Issue 6 Pg. 632-40 (Dec 2015) ISSN: 1432-2129 [Electronic] Germany
• Vernacular Title: Topisches Ambroxol zur Behandlung neuropathischer Schmerzen: Eine erste klinische Beobachtung.
• PMID: 26597641 (Publication Type: Case Reports, Comparative Study, Journal Article)

Chemical References

• Ambroxol
• Lidocaine
• Capsaicin

Topics

• Administration, Topical
• Adult
• Aged
• Aged, 80 and over
• Ambroxol (administration & dosage, adverse effects)
• Capsaicin (administration & dosage)
• Female
• Humans
• Lidocaine (administration & dosage)
• Long-Term Care
• Male
• Middle Aged
• Neuralgia (drug therapy, etiology)
• Pain Measurement (drug effects)
• Pain, Postoperative (drug therapy, etiology)
• Retrospective Studies