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Ferrous sulfate reduces levodopa bioavailability: Chelation as a possible mechanism
Author(s) -
Campbell N R C,
Hasinoff B
Publication year - 1989
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1038/clpt.1989.21
Subject(s) - levodopa , bioavailability , ferrous , chemistry , crossover study , sulfate , pharmacology , chelation , medicine , inorganic chemistry , parkinson's disease , organic chemistry , alternative medicine , disease , pathology , placebo
This study examined the effect of ferrous sulfate, a widely used iron treatment, on levodopa bioavailability in normal subjects. A 250 mg tablet of levodopa was taken with and without a 325 mg tablet of ferrous sulfate by eight normal subjects in a randomized crossover trial. When levodopa was taken with ferrous sulfate there was a 55% decrease in peak levodopa levels (3.6 ± 2.6 vs 1.6 ± 0.82 nmol/ml; p < 0.05) and a 51% decrease in AUC (257 ± 133 vs 125 ± 51 nmol · min/ml; p < 0.01). Persons with the highest peak levodopa levels and AUC after levodopa alone had the greatest reduction in peak levodopa levels and AUC after levodopa ingestion with ferrous sulfate. Iron in its ferrous state is oxidized rapidly to the ferric state in the presence of levodopa at pHs found in the small intestine. In the ferric state, iron binds very strongly to levodopa. Chelation of iron by levodopa is the likely mechanism for this drug interaction. The clinical significance of this interaction is yet to be established. Clinical Pharmacology and Therapeutics (1989) 45, 220–225; doi: 10.1038/clpt.1989.21