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Drug Interactions between Duopa and Rytary

This report displays the potential drug interactions for the following 2 drugs:

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Interactions between your drugs

No interactions were found between Duopa and Rytary. However, this does not necessarily mean no interactions exist. Always consult your healthcare provider.

Duopa

A total of 482 drugs are known to interact with Duopa.

Rytary

A total of 482 drugs are known to interact with Rytary.

Drug and food interactions

Moderate

levodopa food

Applies to: Duopa (carbidopa / levodopa) and Rytary (carbidopa / levodopa)

GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of levodopa. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.

MONITOR: Limited clinical data suggest that high protein content in the diet may reduce or cause fluctuations in the clinical response to levodopa in patients with Parkinson's disease. Proposed mechanisms include delayed gastric emptying, decreased levodopa absorption when taken with a protein rich diet, and competition with certain amino acids for transport across the gut wall and/or the blood brain barrier. Data have been conflicting. Clinical studies have variously reported no effect, reduced levodopa absorption with low-protein meals, reduced effects of levodopa with high daily protein intake, and no differences compared to fasting with high-protein meals. Neuroleptic malignant-like symptoms were reported in a patient with Parkinson's disease who was receiving pramipexole, entacapone, and immediate-release levodopa/carbidopa, after the protein content of his enteral feedings via nasogastric tube was increased from 0.88 g/kg/day to 1.8 g/kg/day; symptoms improved after the protein was reduced to 1 g/kg/day and bromocriptine was administered. Another patient receiving immediate-release carbidopa/levodopa, pramipexole, and entacapone experienced severe rigidity after initiation of continuous enteral nutrition via oral gastric tube containing 1.4 g/kg/day of protein; his Parkinsonian symptoms improved after the protein content was reduced to 0.9 g/kg/day, the feeding was changed to bolus feedings, and the levodopa was administered between boluses.

MANAGEMENT: In general, alcohol consumption should be avoided or limited during treatment with CNS-depressant agents. Until more data are available, it is advisable to avoid large fluctuations in daily protein intake and to monitor patients for altered effects of levodopa if the protein content of the diet is increased.

References

  1. Wohlt PD, Zheng L, Gunderson S, Balzar SA, Johnson BD, Fish JT "Recommendations for the use of medications with continuous enteral nutrition." Am J Health Syst Pharm 66 (2009): 1438-67

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Moderate

levodopa food

Applies to: Duopa (carbidopa / levodopa) and Rytary (carbidopa / levodopa)

ADJUST DOSING INTERVAL: The oral bioavailability and pharmacologic effects of levodopa and carbidopa may be decreased during concurrent administration with iron-containing products. The proposed mechanism is chelation of levodopa and carbidopa by the iron cation, forming an insoluble complex that is poorly absorbed from the gastrointestinal tract. In nine patients with Parkinson's disease, administration of levodopa-carbidopa 100 mg-25 mg with ferrous sulfate 325 mg decreased levodopa peak plasma concentration (Cmax) and systemic exposure (AUC) by 47% and 30%, respectively, and carbidopa Cmax and AUC by 77% and 82%, respectively, compared to administration with placebo. There was also evidence of reduced efficacy of levodopa in some patients. In another study consisting of eight healthy subjects, coadministration of levodopa 250 mg with ferrous sulfate 325 mg resulted in greater than 50% reductions in the Cmax and AUC of levodopa compared to administration of levodopa alone. The magnitude of the interaction was the greatest in patients whose plasma levels of levodopa were the highest following administration of levodopa alone.

MANAGEMENT: Until more information is available, patients receiving levodopa and/or carbidopa in combination with iron-containing products should be advised to separate the times of administration by as much as possible. Patients should be monitored for reduced efficacy of levodopa, and the dosage adjusted as necessary.

References

  1. Campbell NR, Hasinoff B "Ferrous sulfate reduces levodopa bioavailability: chelation as a possible mechanism." Clin Pharmacol Ther 45 (1989): 220-5
  2. Campbell NR, Hasinoff BB "Iron supplements: a common cause of drug interactions." Br J Clin Pharmacol 31 (1991): 251-5
  3. Campbell NR, Rankine D, Goodridge AE, Hasinoff BB, Kara M "Sinemet-ferrous sulphate interaction in patients with Parkinson's disease." Br J Clin Pharmacol 30 (1990): 599-605
  4. Greene RJ, Hall AD, Hider RC "The interaction of orally administered iron with levodopa and methyldopa therapy." J Pharm Pharmacol 42 (1990): 502-4
View all 4 references

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Therapeutic duplication warnings

Therapeutic duplication is the use of more than one medicine from the same drug category or therapeutic class to treat the same condition. This can be intentional in cases where drugs with similar actions are used together for demonstrated therapeutic benefit. It can also be unintentional in cases where a patient has been treated by more than one doctor, or had prescriptions filled at more than one pharmacy, and can have potentially adverse consequences.

Duplication

Dopaminergic agents for parkinsonism

Therapeutic duplication

The recommended maximum number of medicines in the 'dopaminergic agents for parkinsonism' category to be taken concurrently is usually one. Your list includes two medicines belonging to the 'dopaminergic agents for parkinsonism' category:

  • Duopa (carbidopa/levodopa)
  • Rytary (carbidopa/levodopa)

Note: In certain circumstances, the benefits of taking this combination of drugs may outweigh any risks. Always consult your healthcare provider before making changes to your medications or dosage.


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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.