Sodium Channel Blockers

Medication Names:

Lidocaine (Lidoderm® patch), Mexilitine (Mexitil®), Ketamine, Amantadine (Symmetrel®)

On Label Use:

Lidocaine is a local anesthetic, used systemically for arrythmias

Mexilitine is used for arrythmias

Ketamine is a dissociative anesthetic

Amantadine is used to treat Parkinson's disease and some viral infections

Pain Use:

Lidocaine is injected as a short acting local anesthetic. The Lidoderm® patch is a 5% patch with on label use recommended for local treatment of post-herpetic neuralgia. Off label uses are for neuropathic pain (CRPS 1 and 2, painful neuroma), myofascial trigger points. The patch should be worn for no more than a 12 hour period, then it should be removed for 12 hours. Systemic Lidocaine should not be used, as it is dangerously toxic.

Mexiletine is used to decrease neuropathic pain (CRPS 2)

Ketamine is used in oral preparations, iv delivery systems, in skin preparations via Organogel® and other delivery methods. Organogel® delivery can be compounded in various percentages. This seems to be the safest and best tolerated delivery system. This is treatment best left to pain specialists

Amantadine is used to decrease neuropathic pain (CRPS type 1 and 2)

Therapeutic Benefit:

Decreased burning, electrical, shooting pain caused by nerve damage. Lidoderm® patches may help with myofascial trigger points, as well. Lidoderm® provides local treatment without systemic absorption. Ketamine in Organogel® may provide a similar benefit

Dose Range:

Lidoderm® is used for a maximum of 12 hours on then 12 hours off. When using more than one patch, these should always be on during the same 12 hours. Current studies are being conducted to determine if the patches can be left on for longer periods of time before removal. Lidocaine injections are useful in treating myofascial trigger points and 1% or 2% can be delivered with a 25 to 27 gauge needle. Training should be attained before performing these injections. Lidocaine is very dangerous if absorbed systemically.


Lidocaine- none. For Lidoderm patches these should be worn for up to 12 hours and then removed for 12 hours to avoid any significant systemic absorption

Side Effects:

Lidocaine- lightheadedness, occasional vaso-vagal response with injections.

Drug Interactions:

Lidocaine used locally has no significant drug interactions

Dependency or Abstinence Syndrome:






Bay Area Pain Medical Associates provides the information as a guideline for physicians interested in up to date knowledge about the treatment of pain in their patients. We provide this as a public service without endorsing any specific treatment. Much of the medication used in managing pain is for "off label" use. Physicians using these medication are responsible for researching their efficacy, side effects, therapeutic benefits, interactions, titration and cessation, before deciding whether to use them in their practice. While we have provided information on these subjects, we do not feel this should serve as a substitute for looking up medications in standard texts and resources. When medications are left out of dosing, titration, drug interaction and side effect categories, it is because we do not think they should be used by anyone except for pain specialists.