Study Supports Injected Methylcobalamin for Subacute Herpetic Neuralgia Treatment

Results of a recent clinical trial by researchers at the Department of Rehabilitation Medicine in the Affiliated Tenth People’s Hospital of Tongji University, in Shanghai, China, have deemed locally injected methylcobalamin more effective than its orally administered counterpart as a treatment for subacute herpetic neuralgia, which refers to pain persisting between one and four months after a herpes zoster rash heals.

Since shingles is most common and most severe in geriatric patients, according to the National Institute on Aging, the authors of “Single-Center Randomized Controlled Trial of Local Methylcobalamin Injection for Subacute Herpetic Neuralgia,” published online in Pain Medicine on April 8, 2013, enrolled 98 patients who were at least 50 years old and had moderate-to-severe unilateral, dermatomal pain related to herpes zoster on their torsos that lasted for 30 days after the onset of their rashes.

Once enrolled, patients were randomized to receive local methylcobalamin injection, oral methylcobalamin, or subcutaneous 1.0 percent lidocaine injection for four weeks. After the 28-day treatment period, Gang Xu, MD, and colleagues at Tongji University recorded each patient’s scores on worst pain severity, global impression of change, continuous spontaneous pain, paroxysmal pain, allodynia, paresthesia, interference with activities of daily living, and quality of life.

Reviewing the results of the three treatment groups, the researchers found that the 33 patients who received methylcobalamin orally exhibited a substantial response to treatment after 14 days (P&thinsp;<&thinsp;0.001), but the oral form of the drug didn’t provide any significant pain relief for their subacute herpetic neuralgia (P&thinsp;>&thinsp;0.05).

In comparison, the 33 patients who received methylcobalamin via local injection showed improved “overall pain (P&thinsp;<&thinsp;0.001), continuous spontaneous pain (P&thinsp;<&thinsp;0.05), paroxysmal pain (P&thinsp;<&thinsp;0.05), and allodynia (P&thinsp;<&thinsp;0.05).” Additionally, 20 of those 33 patients treated with injected methylcobalamin achieved at least 50 percent pain reduction, and 24 stopped using analgesics at the study’s end point. Quality of life and activities of daily living also significantly improved in the injected methylcobalamin group compared to the oral methylcobalamin group and the subcutaneous lidocaine injection group (P&thinsp;<&thinsp;0.001).

Considering those results, the authors concluded, “local methylcobalamin injection was not only efficacious in relieving pain, but also appears to be tolerable and a potential choice of treatment for subacute herpetic neuralgia.”