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[NawlinsGirl]

Abstracts from the Recent Literature

A trial of intravenous lidocaine on the pain and allodynia of postherpetic neuralgia.
Baranowski AP, De Courcey J, Bonello E. J Pain Symptom Manage. 1999;17:429-433.

ABSTRACT
Background and Objectives
An IV infusion of lidocaine has been frequently used to produce analgesia in neuropathic pain. Low doses of lidocaine are less likely to produce complications while remaining clinically useful in reducing pain. Thus, the aim of the study was to determine whether low doses of lidocaine have an analgesic effect in patients with PHN, and whether they could reduce not only episodes of ongoing pain but also the evoked pain and the area of allodynia (pain from light touch).

Goals of the Study
To investigate the effect of IV lidocaine at 2 doses (1 mg/kg and 5 mg/kg over 2 hours) and IV saline placebo on the pain and allodynia of PHN.

Study Design
Twenty-four elderly patients with refractory PHN for longer than 1 year were studied using a randomized, double-blind, within patient crossover design. Each patient received normal saline, lidocaine 0.5 mg/kg/hr, and lidocaine 2.5 mg/kg/hr over a 2-hour period, at least 1 week apart. Free plasma lidocaine levels, the McGill Pain Questionnaire Short Form, visual analog scores (VAS),
and area of allodynia were measured three times prior to, and at 15-minute intervals during, the infusions.

Results
The VAS for ongoing pain showed a significant reduction after all three infusions (P < 0.05). For dynamic pressure-provoked pain, the VAS was unaffected by placebo but showed a reduction at an equal level of significance with both lidocaine infusions (P < 0.05). The area of allodynia of PHN, as mapped by camel hair brush stroke, declined in association with IV lidocaine (0.5 mg/kg/h, P < 0.05; 2.5 mg/kg/h, P < 0.001). Placebo had no significant effect on the area of allodynia.

Conclusion
These findings demonstrate a positive effect on pain and allodynia following a brief IV infusion of low-dose lidocaine. Since the elderly often have significant cardiovascular pathology, 1 mg/kg over 2 hours is preferred. The higher-dose infusion may produce plasma levels in the toxic range with no significant clinical increase in response.

COMMENTARY
The patients treated in this study had suffered from PHN for an average of 3.25 years. Many treatments had been tried, but none had worked. Therefore, it is exciting to find that low-dose lidocaine over 2 hours was
able to produce and maintain a therapeutic plasma level of lidocaine that
had an effect against the dynamic pressure-provoked pain and allodynia.
However, 2-hour pain reduction may not be enough to make this treatment worthwhile, and the authors did not record whether pain relief continued after the cessation of therapy. Such an outcome would be ideal, as patients would generally be willing to have a weekly 2-hour infusion if it had a marked effect on long-term quality of life. It is unlikely that low-dose IV lidocaine had the required long-term effect on pain relief or quality of life since while the area of allodynia and its sensitivity was reduced, it was not abolished. Furthermore, placebo was just as effective as lidocaine for reducing ongoing pain.
THE VZV RESEARCH
FOUNDATION (VZVRF)
WAS ESTABLISHED
IN 1991 BY
RICHARD PERKIN

American Herpes Foundation Monitor

[mattsmom]

Interesting. We see Marcaine, etc in epidurals already;so wonder if we will see topical or SQ forms of 'caines more commonly used as well. Even combined with MS04 in the morphine pumps for chronic pain, etc. (maybe they already do that?!..haven't been involved with the chronic pain setting for awhile)

Deb

[enkiud911]

When not in ER, I work in a pain clinic. Weve done at least 5 lido drips, only one has been successfull. Your article however doesnt comment on follow up with PO lidocane as therapy after drip. Literature states it is mandatory for therapy use.