Levodopa is the precursor required by the brain to produce dopamine, a neurotransmitter (chemical messenger in the nervous system). People with Parkinson’s disease have depleted levels of dopamine. Levodopa is used to increase dopamine in the brain, which reduces the symptoms of Parkinson’s disease. Levodopa is broken down by the body before it reaches the brain. To avoid this, levodopa is used with carbidopa, a drug that protects levodopa from breakdown. Levodopa is available alone or in a combination product.
Summary of Interactions with Vitamins, Herbs, and Foods
In some cases, an herb or supplement may appear in more than one category, which may seem contradictory. For clarification, read the full article for details about the summarized interactions.
 May be Beneficial: Depletion or interference—The medication may deplete or interfere with the absorption or function of the nutrient. Taking these nutrients may help replenish them. | Vitamin B6 |
| Side effect reduction/prevention | None known |
| Supportive interaction | None known |
| Reduced drug absorption/bioavailability | None known |
| Adverse interaction | None known |
An asterisk (*) next to an item in the summary indicates that the interaction is supported only by weak, fragmentary, and/or contradictory scientific evidence.
Interactions with Dietary Supplements
Vitamin B6
Levodopa is broken down in the body by a process requiring vitamin B6. Breakdown may deplete available vitamin B6. Carbidopa blocks levodopa breakdown and prevents vitamin B6 depletion. People taking levodopa/carbidopa (Sinemet®), or levodopa plus carbidopa (Lodosyn®) have no risk for levodopa-induced vitamin B6 deficiency; it is not a problem for people to supplement vitamin B6 while taking Sinemet.
For people taking levodopa alone, small amounts of vitamin B6 (5–10 mg per day) may prevent levodopa-induced vitamin B6 deficiency.1 Amounts of vitamin B6 slightly higher than those required to replace depleted levels, may reduce the effectiveness of levodopa therapy and should not be taken.2
Interactions with Foods and Other Compounds
Food
Food, especially foods high in protein, compete with levodopa for absorption. However, levodopa may be taken with food to avoid stomach upset.3 It is important to take levodopa at the same time every day, always with or always without food. People with questions about levodopa and food should ask their prescribing doctor or pharmacist. Taking sustained-release Sinemet® CR with food may increase blood levels of levodopa.4 It is important to take Sinemet® CR at the same time every day, always with or always without food. People with questions about Sinemet® CR and food should ask their prescribing doctor or pharmacist.
References
1. Long JW. The Essential Guide to Prescription Drugs 1992. New York: Harper Perennial, 1991.
2. Trovato A et al. Drug-nutrient interactions. Am Family Phys 1991;44:1651–8.
3. Threlkeld DS, ed. Central Nervous System Drugs, Antiparkinson Agents, Levodopa. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Sep 1991, 289p–290a.
4. Threlkeld DS, ed. Central Nervous System Drugs, Antiparkinson Agents, Levodopa. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Sep 1991, 289p–290a.
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2006-09-07
