title: Interference between eplerenone and digoxin in fluorescence polarization immunoassay, microparticle enzyme immunoassay, and affinity column-mediated immunoassay.
abstract: Digitalis-like immunoreactive substances have crossreactivity with antidigoxin antibodies and the interference between digoxin and spironolactone/canrenone has been reported. The structure of eplerenone is similar to that of spironolactone/canrenone. Therefore, we hypothesized that eplerenone might also interfere with the measurement of digoxin by immunoassay. We performed three types of assays (fluorescence polarization immunoassay [FPIA], microparticle enzyme immunoassay [MEIA], and affinity column-mediated immunoassay [ACMIA]) to determine crossreactions between eplerenone and antidigoxin antibodies. Furthermore, we used FPIA, MEIA, and ACMIA to measure the apparent digoxin concentration in mixed solutions of eplerenone (1-100 μg/mL) and digoxin (1-3 ng/mL). In the crossreaction tests, eplerenone was detected as digoxin by FPIA and ACMIA. By FPIA, a known concentration of 1 μg/mL of eplerenone was measured as 0.33 ± 0.11 ng/mL of digoxin (crossreaction rate, 0.03%). By ACMIA, a known concentration of 10 μg/mL of eplerenone was measured as 0.13 ± 0.05 ng/mL of digoxin (crossreaction rate, 0.001%). No crossreaction between eplerenone and digoxin was determined by MEIA. In the interference of eplerenone coadministered with digoxin, the apparent concentration of digoxin was increased in FPIA, but decreased in MEIA and ACMIA. The results suggest that eplerenone crossreacts with antidigoxin antibodies in FPIA, MEIA, and ACMIA, but that the interference of eplerenone might be smaller than that of spironolactone/canrenone.
authors.affiliation: Department of Pharmacy, Osaka Medical College Hospital, Osaka, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Yamada
authors.forename: Kaoru
authors.initials: K
authors.lastname: Suzuki
authors.forename: Ken
authors.initials: K
authors.lastname: Iguchi
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Kanada
authors.forename: Ryuji
authors.initials: R
authors.lastname: Kato
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Ijiri
authors.forename: Masami
authors.initials: M
authors.lastname: Nishihara
authors.forename: Sumiko
authors.initials: S
authors.lastname: Murakami
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Hayashi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tamai
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Tanaka
mesh_terms: D000889:Anti-Arrhythmia Agents / Q000097:blood* / Q000276:immunology; D000906:Antibodies / Q000276:immunology; D003429:Cross Reactions; D004077:Digoxin / Q000097:blood* / Q000276:immunology; D000077545:Eplerenone; D016231:Fluorescence Polarization Immunoassay; D006801:Humans; D007118:Immunoassay; D066298:In Vitro Techniques; D000451:Mineralocorticoid Receptor Antagonists / Q000097:blood* / Q000276:immunology; D013148:Spironolactone / Q000031:analogs & derivatives* / Q000097:blood / Q000276:immunology
chemical_list: D000889:Anti-Arrhythmia Agents; D000906:Antibodies; D000451:Mineralocorticoid Receptor Antagonists; D013148:Spironolactone; D000077545:Eplerenone; D004077:Digoxin