I have recently, reluctantly, been using a diclofenac gel for a painful foot. Looking up diclofenac to check various things, I noticed this paper.
I had not previously considered B12 to be an analgesic! (Though well aware of the neuropathy issues that a deficiency can cause.) And I was surprised by the potentiation effect of B12 on diclofenac.
Do be aware this is a veterinary paper - might not be the same in humans.
Vet Res Forum. 2013 Winter; 4(1): 19–24.
PMCID: PMC4293892
PMID: 25593681
The effects of vitamin B12 and diclofenac and their combination on cold and mechanical allodynia in a neuropathic pain model in rats
Esmaeal Tamaddonfard,1,* Farzad Samadi,2 and Karim Egdami2
Abstract
The present study was performed to investigate the effects of long-term intraperitoneal (IP) injection of vitamin B12 and diclofenac in separate and combined treatments on cold and mechanical allodynia in a neuropathic pain model in rats. Neuropathic pain was induced by crush injury in right tibial nerve. Acetone spray and von Frey tests were used to obtain cold and mechanical allodynia responses, respectively, on day 11 after nerve crush. Normal saline, vitamin B12 and diclofenac were injected intraperitoneally for 10 consecutive days after surgery. Normal saline treated rats showed cold and mechanical allodynia responses after nerve crush. Vitamin B12 at doses of 50, 100 and 200 µg kg-1 and diclofenac at a dose of 2 mg kg-1 produced antiallodynic effects. Antiallodynic effects were not observed when subanalgesic doses of vitamin B12 (25 µg kg-1) and diclofenac (0.25 mg kg-1) were used together. By increasing the dose of vitamin B12 to an effective dose (100 µg kg-1), antiallodynic effects were observed when compared with diclofenac (0.25 mg kg-1) alone. The results indicated that vitamin B12 and diclofenac produced neuropathic pain suppressing effects. Moreover, a potentiation effect was observed between vitamin B12 and diclofenac.
Key Words: Allodynia, Diclofenac, Rats, Tibial nerve injury, Vitamin B12
ncbi.nlm.nih.gov/pmc/articl...
(I tried to check if this had previously been posted but HU's search didn't find anything. Apologies if it is a repeat.)