Increased intestinal absorption of foreign organic compounds in the presence of ethylenediaminetetraacetic acid (EDTA) Original paper

What was studied?

The effect of EDTA on intestinal permeability was investigated in a short original research communication assessing whether the calcium-chelating agent disodium EDTA can enhance the intestinal absorption of poorly absorbed, lipid-insoluble “foreign” organic compounds. The authors tested the idea that these compounds normally fail to cross the gut epithelium because they cannot diffuse through lipid membranes and are generally too large to traverse aqueous pores or intercellular spaces, but that EDTA might loosen this barrier and thereby increase uptake.

Who was studied?

The experiments were conducted in male Sprague–Dawley rats (200–250 g) fasted for 18 hours with free access to water, anesthetized, and surgically prepared with ligatures at the pylorus and ileocecal junction; the bile duct was ligated, and renal pedicles were ligated in most experiments to raise measurable blood levels of poorly absorbed drugs. Animals received 5 mL of isotonic buffered saline (pH 7.4) containing each test compound alone or the same solution plus 10 mg/mL disodium EDTA, and absorption was quantified over 1 hour by mass balance (administered minus recovered from lumen and tissue) and by plasma levels. Each drug condition was studied in 8–12 animals.

Most important findings

Across multiple chemical classes, EDTA consistently increased intestinal uptake and systemic exposure, implying a broad effect on epithelial barrier function rather than compound-specific chemistry. Two neutral polysaccharide/polyol probes (mannitol and inulin), normally absorbed <2%, rose to 7–11% with EDTA, with plasma radioactivity increasing ~5- to 6-fold. A quaternary ammonium compound (decamethonium) increased from 2–3% absorption to 11–15%, again with ~5- to 6-fold higher plasma levels. Two organic acids (sulfanilic acid and labeled EDTA) increased from 11–14% to 26–32%, with ~5-fold higher plasma concentrations. To directly test barrier permeability, the authors measured movement in the opposite direction: intravenously administered inulin appearing in the intestinal lumen increased 4-fold when EDTA was present intraluminally, supporting an EDTA-driven increase in the permeability of the blood–intestinal boundary. Mechanistically, they propose that EDTA chelates calcium, potentially enlarging membrane “pores” or widening intercellular spaces by disrupting calcium-dependent junctional integrity. While not a microbiome study, these findings are clinically relevant to microbiome-related therapeutics because epithelial permeability and divalent-cation availability can modulate luminal–host interactions and the apparent efficacy/toxicity of orally delivered agents.

Key implications

This work suggests EDTA can act as a non-specific absorption enhancer by increasing intestinal epithelial permeability, likely via calcium chelation and junctional/space remodeling, rather than by drug-specific complexation effects alone. Clinically, this raises both opportunity and caution: EDTA-like excipients could improve oral delivery of hydrophilic or large molecules, but may also increase unintended absorption of luminal antigens, toxins, or microbial products—phenomena central to “leaky gut” frameworks and potentially confounding microbiome-intervention outcomes. In microbiome-informed practice, EDTA-containing formulations could alter host exposure to microbial metabolites (and thus biomarker readouts) independently of any true microbial community change, underscoring the need to document excipients and barrier-modifying co-therapies when interpreting microbiome signatures.

Citation

Lewis S. Schanker, Jean M. Johnson, Increased intestinal absorption of foreign organic compounds in the presence of ethylenediaminetetraacetic acid (EDTA), Biochemical Pharmacology, Volume 8, Issue 4, 1961, Pages 421-422.