On 2014 Jul 29, David Keller commented:

B vitamins for levodopa-associated peripheral neuropathy

The problem: "Cases of symptomatic peripheral neuropathy [PN], sometimes severe, have been reported in patients receiving LCIG [levodopa/carbidopa intestinal gel]. Cases are generally a sensorimotor polyneuropathy with both subacute and chronic onsets, often associated with vitamin B12 and/or B6 deficiency."

Observation: "Cases of LCIG-associated PN often have responded to vitamin supplementation"

Advice: "It may be advisable to monitor vitamin B12/B6 status before and after patients start LCIG and be vigilant for signs of PN. Prospective, large-scale, long-term studies are needed."

Administration of levodopa is associated with elevation of blood levels of homocysteine, a neurotoxic waste product which consumes vitamins B6, B12 and folic acid during its metabolism (1). Administration of these B-complex vitamins has been demonstrated to lower homocysteine levels, with postulated favorable effects on neurological degeneration (2). However, while I agree with the recommendation to monitor levels of B12 and B6 during levodopa therapy, I would add the suggestion that homocysteine levels be monitored directly as well, since homocysteine is the actual neurotoxin. Preventative addition of a vitamin B-complex supplement if taking levodopa is also reasonable, despite the lack of evidence from a clinical trial yet. By the time homocysteine-mediated peripheral neuropathy is symptomatic, it may be difficult or impossible to reverse.

References

1: Obeid R, Herrmann W. Mechanisms of homocysteine neurotoxicity in neurodegenerative diseases with special reference to dementia. FEBS Lett. 2006 May 29;580(13):2994-3005. Epub 2006 May 6. Review. PubMed PMID: 16697371.

2: Cacciapuoti F. Lowering homocysteine levels with folic acid and B-vitamins do not reduce early atherosclerosis, but could interfere with cognitive decline and Alzheimer's disease. J Thromb Thrombolysis. 2013 Oct;36(3):258-62. doi: 10.1007/s11239-012-0856-x. Review. PubMed PMID: 23224755.

On 2014 Jul 29, David Keller commented:

B vitamins for levodopa-associated peripheral neuropathy

The problem: "Cases of symptomatic peripheral neuropathy [PN], sometimes severe, have been reported in patients receiving LCIG [levodopa/carbidopa intestinal gel]. Cases are generally a sensorimotor polyneuropathy with both subacute and chronic onsets, often associated with vitamin B12 and/or B6 deficiency."

Observation: "Cases of LCIG-associated PN often have responded to vitamin supplementation"

Advice: "It may be advisable to monitor vitamin B12/B6 status before and after patients start LCIG and be vigilant for signs of PN. Prospective, large-scale, long-term studies are needed."

Administration of levodopa is associated with elevation of blood levels of homocysteine, a neurotoxic waste product which consumes vitamins B6, B12 and folic acid during its metabolism (1). Administration of these B-complex vitamins has been demonstrated to lower homocysteine levels, with postulated favorable effects on neurological degeneration (2). However, while I agree with the recommendation to monitor levels of B12 and B6 during levodopa therapy, I would add the suggestion that homocysteine levels be monitored directly as well, since homocysteine is the actual neurotoxin. Preventative addition of a vitamin B-complex supplement if taking levodopa is also reasonable, despite the lack of evidence from a clinical trial yet. By the time homocysteine-mediated peripheral neuropathy is symptomatic, it may be difficult or impossible to reverse.

References

1: Obeid R, Herrmann W. Mechanisms of homocysteine neurotoxicity in neurodegenerative diseases with special reference to dementia. FEBS Lett. 2006 May 29;580(13):2994-3005. Epub 2006 May 6. Review. PubMed PMID: 16697371.

2: Cacciapuoti F. Lowering homocysteine levels with folic acid and B-vitamins do not reduce early atherosclerosis, but could interfere with cognitive decline and Alzheimer's disease. J Thromb Thrombolysis. 2013 Oct;36(3):258-62. doi: 10.1007/s11239-012-0856-x. Review. PubMed PMID: 23224755.