Combination medication for the treatment of neuropathic pain

22nd July 2008 at 12:15 BST by Dr.C.A.Jenner MB BS, FRCA. Permalink.

Article on Combination medication for the treatment of neuropathic pain

Combination medication for the treatment of neuropathic pain

Introduction

Neuropathic pain is a complex, chronic pain state, most often accompanied by a tissue injury. According to various studies, neuropathic low back pain affects an estimated 5.6 million people in the US. The condition is typically characterized by a burning and shooting pain, along with a feeling of tingling and numbness.

Forms of Neuropathic Pain

The most common forms in which neuropathic pain manifests itself include:

• Postherpetic neuralgia
• Reflex sympathetic dystrophy/nerve trauma
• Components of cancer pain
• Phantom limb pain
• Entrapment neuropathy (.e.g. carpal tunnel syndrome)
• Peripheral neuropathy (vast nerve damage)

Shooting or lancinating pain, burning pain, paraesthesia, dysaesthesia, numbness and allodynia (pain produced by a non-painful stimulus) are the most prominent characteristics of neuropathic pain.

Pharmacologic Management

Pharmacologic treatment is the mainstay for treating neuropathic pain. This form of pain is known to respond the best to a combination medication.

The main drug groups used include:

• Topical agents
• Tricyclic antidepressants
• Anticonvulsants
• Nonopioid analgesics

The Underlying Principle

There is a specific underlying principle for the use of combination medicine for neuropathic pain. The mechanism of action is reduction of neuronal hyperexcitability, either peripherally or centrally, while the nerve impulses are blunted.

It should be noted that carbamazepine is reportedly the only FDA-approved indication for neuropathic pain, specifically trigeminal neuralgia.

In the following sections, we've given brief details on the combination medication prescribed for relief from neuropathic pain.

• Topical Agents

  This category of medication offers the benefit of local toxicity without systemic toxicity.

  The most common medication in this category includes:

  • Capsaicin Cream – This medication carries an extract of chili peppers and is used to treat neuropathic pain. A burning sensation that reduces with consistent use is the most prominent side effect of this medicine.
  • Lidocaine – This medication is especially used in its newly approved patch form.

• Antidepressants

  Tricyclic antidepressants as well as serotonin reuptake inhibitors are used to treat neuropathic pain. Tricyclic antidepressants (TCAs) are generally considered as the first-line agents for all neuropathies, except trigeminal neuralgia.

  Amitrptyline is known to be the first tricyclic used for the treatment of neuropathy. Desipramine and nortriptyline have the least side effects in the category of tricyclic antidepressants.

  Recently, venlafaxine is also gaining interest as a prospective treatment for neuropathic pain. The most common side effects of venlafaxine include increased blood pressure, hypertension, irritability, insomnia, nausea, vomiting and constipation.

• Anticonvulsants

  Anticonvulsants are widely accepted as the second-line of therapy for most of the neuropathies. The most common medicines in this category include:

  • Carbamazepine
  • Phenytoin
  • Gabapentin
  • Lamotrigine

  Some of the most common side effects of these medicines include dizziness, giddiness, dyspepsia, asthenia, headache, somnolence and the like.

• Antiarrhythmics

  A major proportion of the antiarrhythmics have a sodium-blocking activity. Medications like the low-dose IV lidocaine are sometimes used for temporary pain relief from peripheral nervous system injuries, including diabetic neuropathy and post herpetic neuralgia. In addition, it is also used as a diagnostic tool to discern neuropathic pain from idiopathic, myofascial and central pain.

  Meanwhile, mexiletine also decreases pain associated with traumatic neuropathy.

  Most common side effects associated with the use of antiarrhythmics include nausea, vomiting, dyspepsia, dizziness, tremor and ataxia.

• Analgesics

  Analgesics are generally not accepted as the first-line of treatment for relief from neuropathic pain. However, when used as a combination medication for treating neuropathic pain, a few analgesics have been found to be quite effective.

  Besides, novel analgesics such as tradamol might offer more options for relief from neuropathy.

• NSAIDs

  Though not all in general, yet some of the NSAIDs are quite effective for neuropathic pain relief. For instance, medication like ibuprofen and sulindac offer substantial relief from diabetic neuropathy.

• Opioids

  Though opioid use for treatment of neuropathic pain has been a controversial matter, yet recent research supports the use of opioids in patients who have failed other modalities.

• Other Agents

  Some of the other medication used for treatment of neuropathic pain includes:

  • Baclofen - Used as a first-line agent for the treatment of trigeminal neuralgia.
  • Transdermal clonidine – Partially successful in treating diabetic neuropathy.
  • Ketamine – Successful in treating neuropathic pain associated with various conditions.

Important Information

Medication based treatment of neuropathic pain continues to be a subject of scientific research. Any medication to be used for this purpose must be weighed for benefits and risks before it is administered, in context of the specific individual's state of health.

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