A single-center randomized controlled trial of local methylcobalamin injection for subacute herpetic neuralgia.

OBJECTIVE: This study explored the efficacy of local methylcobalamin injection in relieving pain and improving the quality of life among subjects with subacute herpetic neuralgia. DESIGN: A single-center, randomized controlled trial of local methylcobalamin injection was performed. SUBJECTS: Ninety-eight subjects (age, ≥ 50 years) with unilateral, dermatomal pain ≥ 4 related to herpes zoster on the torso lasting for 30 days after onset of rash were enrolled. METHODS: Subjects were randomized to receive local methylcobalamin injection (N = 33), oral methylcobalamin (N = 33), or subcutaneous 1.0% lidocaine injection (N = 32) for 4 weeks. Worst pain severity, global impression of change, continuous spontaneous pain, paroxysmal pain, allodynia, paresthesia, interference with activities of daily living, and quality of life were assessed after 28-day treatment period. RESULTS: Time per group interaction and group difference on overall pain at each follow-up point were statistically significant (P < 0.001) among groups. In the injected methylcobalamin group, the overall pain (P < 0.001), continuous spontaneous pain (P < 0.05), paroxysmal pain (P < 0.05), and allodynia (P < 0.05) revealed a significant effect at each follow-up point as compared with the other groups. Twenty subjects achieved pain reduction ≥ 50%, 24 perceived worst pain ≤ 3, 24 stopped using analgesics at end point; activities of daily living and quality of life improved significantly as compared with the other groups (P < 0.001). Although both of the other groups showed a significant response after the 14-day treatment (P < 0.001) compared with the baseline, oral methylcobalamin did not provide any significantly pain relief (P > 0.05). CONCLUSIONS: 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.

Thiamine, cobalamin, locally injected alone or combination for herpetic itching: a single-center randomized controlled trial.

OBJECTIVES: The present study was designed to explore the efficacy of locally injected thiamine or cobalamin in relieving itch or pain and improving the daily living activities among patients with herpetic itching. METHODS: Eighty eligible patients with herpetic itching with a worst itching score of ≥ 4 were randomized to receive locally injected thiamine (B1 group), cobalamin (B12 group), lidocaine (LD group), or combination of thiamine and cobalamin (COB group) for 4 weeks. The treatment efficacy was assessed based on the patients' pruritus and pain severity, global impression of change, and activities of daily living and quality of life. RESULTS: After 7 days, thiamine yielded a significant itch relief, cobalamin yielded a significant pain relief, and their combination significantly relieved both pain and itch; which all continued till the endpoint (all Ps<0.001). However, lidocaine did not provide significant itch or pain relief than the other groups. Sixteen patients in the thiamine group achieved ≥ 30% itch reduction; 18 patients in the cobalamin group obtained ≥ 30% pain reduction; and 18 patients achieved ≥ 30% itch reduction and 19 patients obtained ≥ 30% pain reduction in the combination group. The activities of daily living and quality of life data at the endpoint were consistent with a significant benefit in the thiamine (P<0.05), cobalamin, and combination groups (both Ps<0.001). DISCUSSION: Locally injected thiamine had a significant antipruritic effect, cobalamin had an analgesic effect, and their combination had the dual effect with no obvious synergies. This intervention was efficacious, tolerable, and safe for herpetic itching.