Carbidopa Should Be Considered in Rising Parkinson's Death Rate

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Carbidopa, used to manage L-dopa-induced nausea in Parkinson’s patients, is believed to contribute to the increasing death rate of Parkinson’s disease.

Marty Hinz MD, of NeuroResearch Clinics Inc., and colleagues, postulate that carbidopa, which was approved by the FDA in 1975, may contribute to Parkinson’s classification as a progressive neurodegenerative disease and may even cause L-dopa tachyphylaxis. Carbidopa irreversibly binds to and deactivates pyridoxal 5’-phosphate (PLP), the active form of vitamin B6, a required function of over 300 enzymes and proteins.

In the study, the researchers note that the CDC has documented a 328.7% increase in Parkinson’s deaths between 1976 and 2011. For 15 years prior to 1976, when L-dopa, the most effective treatment known for Parkinson’s disease, was administered in single-ingredient form without carbidopa, the death rate of Parkinson’s patients decreased.

As a result, the researchers question if progressive neurodegeneration in Parkinson’s is related to the disease alone or carbidopa-induced relative nutritional deficiency, and if such drug-induced poisoning could be responsible for the increased death rate.

The researchers emphasize that physicians should fully understand the mechanism of action of the drugs prescribed regardless of indications made by drug manufacturers, and recommend there be more investigation into the consequences of carbidopa use in Parkinson’s disease patients.  

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Carbidopa Should Be Considered in Rising Parkinson's Death Rate

This study raises questions about the possible associations between carbidopa as an anti-nausea medication in Parkinson's disease and an increase in Parkinson's disease death rate. 

Marty Hinz, MD, of NeuroResearch Clinics Inc., and colleagues, note that during the first 15 years of prescribing L-dopa, the only known effective treatment for Parkinson's, a decreasing disease death rate was observed. Then, in 1976, 1 year after US Food and Drug Administration approved the original L-dopa/carbidopa combination drug, the Parkinson's disease death rate started increasing and has continued for 38 years and counting.

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