Interactions between larodopa(levodopa) and Allbee c 800 with iron (multivitamin with iron)
levodopa and multivitamin with iron (Moderate Drug-Drug)
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 resulted in a 47% reduction in the peak plasma concentration (Cmax) and a 30% reduction in the area under the concentration-time curve (AUC) of levodopa compared to administration with placebo. Carbidopa Cmax and AUC decreased 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 normal subjects, coadministration of levodopa 250 mg with ferrous sulfate 325 mg resulted in a greater than 50% decrease 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.
