Methylcobalamin, also referred to as MeB12 and MeCbl, is a member of the cobalamin family and is one of the naturally occurring coenzyme forms of cobalamin found in the human body.

Structurally, Methylcobalamin exists in octahedral form with Cobalt (III) at the center containing metal alkyl bonds[1]. It is considered an equivalent to cobalamin and Vitamin B12 and used as an effective therapeutic agent in Vitamin B12 deficiencies. It is often prescribed in conditions such as diabetic neuropathy, peripheral neuropathy, and amyotrophic lateral sclerosis.

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According to estimates, almost 80% of cobalamin present in body is in the form of methylcobalamin.

Important Functions of Methylcobalamin

  • Critical coenzyme required for methylation through methionine synthase.
  • Plays important role in developing cognitive ability by regulating the myelin sheath and basic structure of nerve cells.
  • Only cobalamin compound that regulates the sleep and wake cycle. It improves the overall quality of sleep and helps in developing nerve cells by maintaining the circadian rhythm aka our body clock.
  • Studies have found a person deficient of methylcobalamin suffers from agitation, anxiety, restlessness and distress.
  • Reduced levels of methylcobalamin can also prompt subacute spinal cord degeneration and megaloblastic iron deficiency.[4]
  • A methyl group provided by methylcobalamin forms a bond with carbon monoxide to generate Acetyl-CoA. Acetyl-CoA is one of the basic compounds to produce other complex organic derivatives for different reactions and metabolic pathways.
  • Methylcobalamin has also been regarded as an important compound in the environment as it’s only produced by a few microorganisms.

Analgesic Effect of Methyl Cobalamin

  1. Neuropathic Pain in Diabetic Neuropathy

One of the important clinical benefits of methylcobalamin is inhibiting pain connected with diabetic neuropathy. The neuropathic pain has been described as a burning and aching irritation which increases the sensitivity of the skin.[5]

Clinical trials have indicated methylcobalamin’s potential in reducing the occurrence and frequency of neuropathic pain associated with diabetes.[6] The studies observed the reduction in overall pain scale score in neuropathic pain after consumption of methylcobalamin.

After four weeks of injectable methylcobalamin, 73% reduction in pain symptoms was observed through Likert-type pain intensity scale. The researchers have identified improved sensory and motor nerve impulses and velocity through consumption of methylcobalamin indicating its significant role as an analgesic[7].

  1. Neuralgia

Considerable reduction in numeric pain values is observed in trigeminal neuralgia, facial neuralgia, sub-acute herpetic neuralgia and glossopharyngeal neuralgia[8]. Intravenous injection of methylcobalamin greatly reduces the symptoms of pain in trigeminal neuralgia whereas reduction of paroxysmal pain, continuous spontaneous pain, and allodynia has also been observed with injectable methyl cobalamin.[9]

Numeric pain scales like Patients’ Global Impression of Change scale and Likert-type pain intensity scale have shown remarkable improvement in pain symptoms due to methylcobalamin neuralgia.[10] It not only reduces the pain symptoms but also ensures improved quality of life.[11]

Neuroprotection and Neuro-synthesis

The majority of therapeutic activity of methylcobalamin is in the form of an analgesic and regulator of homocysteine is due to its positive role in promoting the action and structure of nerve cells as well as providing mechanisms for regeneration of damaged neurons.[12]

Methylcobalamin functions to restore the integrity and strength of the myelin sheath resulting in increased neuroprotection and improved neural conductance. Similarly, methylcobalamin has shown potential in nerve regeneration in many experimental nerve injury models.

As a result of administration of methylcobalamin, the neural functionality, conduction and regeneration has greatly improved in peripheral neuropathies. In many experimental designs, it has also shown improvement in neural densities.

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Lastly, methylcobalamin reduces the level of cysteine in nerve cells by promoting its conversion to the essential amino acid methionine and its effects on homocysteine regulation. This is important since homocysteine has been deemed to be a good cause of vascular and neural degeneration in brain cells.[13] Therefore, regulating the level of homocysteine in brain cells greatly improves the nerve function and structural strength.

Bibliography

[1] Rossi M, Glusker JP, Randaccio L, Summers MF, Toscano PJ, Marzilli LG. The structure of a B12 coenzyme: methylcobalamin studies by X-ray and NMR methods. Journal of the American Chemical Society. 1985 March; 107(6): 1729-38.

[2] Xu G, Lv ZW, Feng Y, Tang WZ, Xu GX. A Single‐Center Randomized Controlled Trial of Local Methylcobalamin Injection for Subacute Herpetic Neuralgia. Pain Medicine. 2013 Jun; 14(6): 884-94. PMID: 23566267.

[3] Okada K, Tanaka H, Temporin K, Okamoto M, Kuroda Y, Moritomo H, Murase T, Yoshikawa, H. Methylcobalamin increases Erk1/2 and Akt activities through the methylation cycle and promotes nerve regeneration in a rat sciatic nerve injury model. ). Experimental neurology. 2010 Apr; 222(2), 191-203. PMID: 20045411.

[4] Xu G, Lv ZW, Feng Y, Tang WZ, Xu GX. A Single‐Center Randomized Controlled Trial of Local Methylcobalamin Injection for Subacute Herpetic Neuralgia. Pain Medicine. 2013 Jun; 14(6): 884-94. PMID: 23566267.

[5] Li G. [Effect of mecobalamin on diabetic neuropathies. Beijing Methycobal Clinical Trial Collaborative Group]. Zhonghua Nei Ke Za Zhi. 1999 Jan; 38(1): 14-7. PMID: 11798619.

[6] Devathasan G, Teo WL, Mylvaganam A. Methylcobalamin (CH3-B12; Methycobal) in chronic diabetic neuropathy. A double-blind clinical and electrophysiological study. 1986.

[7] Dongre YU, Swami OC. Sustained-release pregabalin with methylcobalamin in neuropathic pain: an Indian real-life experience. International Journal General Medicine. 2013 May; 6. 413-7. PMID: 23761981.

[8] Singh PM, Dehran M, Mohan VK, Trikha A, Kaur M. Analgesic efficacy and safety of medical therapy alone vs. combined medical therapy and extraoral glossopharyngeal nerve block in glossopharyngeal neuralgia. Pain Medicine. 2013 Jan; 14(1): 93-102. PMID: 23279193.

[9] Xu G, Lv ZW, Feng Y, Tang WZ, Xu GX. A Single‐Center Randomized Controlled Trial of Local Methylcobalamin Injection for Subacute Herpetic Neuralgia. Pain Medicine. 2013 Jun; 14(6): 884-94. PMID: 23566267.

[10] Singh PM, Dehran M, Mohan VK, Trikha A, Kaur M. Analgesic efficacy and safety of medical therapy alone vs. combined medical therapy and extraoral glossopharyngeal nerve block in glossopharyngeal neuralgia. Pain Medicine. 2013 Jan; 14(1): 93-102. PMID: 23279193.

[11] Teramoto J. Effects of Methylcobalamin on neuralgia. Neurological Therapeutics. 1984; 1(2): 315.

[12] Okada K, Tanaka H, Temporin K, Okamoto M, Kuroda Y, Moritomo H, Murase T, Yoshikawa, H. Methylcobalamin increases Erk1/2 and Akt activities through the methylation cycle and promotes nerve regeneration in a rat sciatic nerve injury model. ). Experimental neurology. 2010 Apr; 222(2), 191-203. PMID: 20045411.

[13] Jensen KP, Ryde, U. Conversion of homocysteine to methionine by methionine synthase: A density functional study. Journal of the American Chemical Society. 2003 Nov; 125(46): 13970-71. PMID: 14611228.