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Amitava Dasgupta - One of the best experts on this subject based on the ideXlab platform.
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clinically insignificant negative interferences of spironolactone Potassium Canrenoate and their common metabolite canrenone in new dimension vista loci digoxin immunoassay
Journal of Clinical Laboratory Analysis, 2012Co-Authors: Amitava Dasgupta, Myrtle Johnson, Tamal K SenguptaAbstract:Spironolactone, a Potassium-sparing diuretic metabolized to canrenone is often used with digoxin to treat various conditions including congestive heart failure. Potassium Canrenoate is a similar drug, which is also metabolized to canrenone. Due to reported both positive and negative interference of spironolactone, Potassium Canrenoate, and their common metabolite canrenone with digoxin immunoassays, we investigated potential interference of these compounds with the new homogenous sequential chemiluminescent assay for digoxin based on the luminescent oxygen channeling technology (LOCI digoxin) for application on the Dimension and Vista platform. When aliquots of a drug-free serum pool were supplemented with various amounts of spironolactone, Potassium Canrenoate, or canrenone and apparent digoxin values were measured using Dimension Vista LOCI digoxin assay, we observed no detected value except when aliquots were supplemented with very high amounts of Potassium Canrenoate or canrenone. However, we observed that apparent digoxin concentrations were very low. When aliquots of a serum digoxin pool (prepared by pooling specimens from patients receiving digoxin), were further supplemented with various amounts of spironolactone, Potassium Canrenoate, or canrenone and serum digoxin concentrations were remeasured using the LOCIdigoxin assay, only statistically significant falsely lower digoxin values (negative interference) were observed in specimens containing very high amounts of canrenone or Potassium Canrenoate. However, such small bias may not have any clinical significance. We conclude that new Dimension Vista LOCI digoxin assay is virtually free from interferences of spironolactone, Potassium Canrenoate, and their common metabolite canrenone.
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abbott architect clinical chemistry and immunoassay systems digoxin assays are free of interferences from spironolactone Potassium Canrenoate and their common metabolite canrenone
Therapeutic Drug Monitoring, 2011Co-Authors: Andrea Defrance, David A Armbruster, Diana Petty, Kelley C Cooper, Amitava DasguptaAbstract:Spironolactone, which is metabolized to canrenone, is often used in combination with digoxin. Potassium Canrenoate is a similar drug that is also metabolized to canrenone. As a result of reported interference of spironolactone, Potassium Canrenoate, and their common metabolite canrenone with digoxin immunoassays, we investigated potential interference of these compounds with two relatively new digoxin assays for application on ARCHITECT clinical chemistry platforms (cDig, particle-enhanced turbidimetric inhibition immunoassay) and ARCHITECT immunoassay platforms (iDig, chemiluminescent microparticle immunoassay), both from Abbott Diagnostics. When aliquots of drug-free serum pool were supplemented with various amounts of spironolactone, Potassium Canrenoate, and canrenone, no apparent digoxin concentration was observed using cDig assay on ARCHITECT c4000, c8000, and c16000 or iDig assay on i1000SR and i2000SR analyzers. In addition, we observed no false increase in serum digoxin value when aliquots of a digoxin pool were further supplemented with various amounts of spironolactone, Potassium Canrenoate, or canrenone. We conclude that both the cDig and iDig assays on the ARCHITECT analyzers are free from interferences by spironolactone, Potassium Canrenoate, and canrenone.
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effect of spironolactone Potassium Canrenoate and their common metabolite canrenone on dimension vista digoxin assay
Journal of Clinical Laboratory Analysis, 2010Co-Authors: Amitava Dasgupta, Myrtle JohnsonAbstract:Spironolactone, a Potassium sparing diuretic metabolized to canrenone, is often used with digoxin to treat various conditions including congestive heart failure. Potassium Canrenoate is a similar drug that is also metabolized to canrenone. Due to reported interference of spironolactone, Potassium Canrenoate, and their common metabolite canrenone with digoxin immunoassays, we investigated potential interference of these compounds with Dimension Vista Digoxin immunoassay using Flex reagent cartridge. Aliquots of a drug-free serum pool were supplemented with various amounts of spironolactone, Potassium Canrenoate, or canrenone and apparent digoxin values were measured using Dimension Vista digoxin assay, we observed none-detected value except when aliquots were supplemented with higher amounts of spironolactone or canrenone. Similarly, when aliquots of a serum digoxin pool (prepared by pooling specimens from patients receiving digoxin) where further supplemented with various amounts of spironolactone, Potassium Canrenoate, or canrenone, we observed moderately falsely elevated digoxin values only in specimens containing higher amounts of spironolactone or canrenone. We conclude that spironolactone and canrenone but not Potassium Canrenoate may cause modest interference with Dimension Vista digoxin assay but such interferences may not be clinically significant except with very high amounts of canrenone. J. Clin. Lab. Anal. 24:413–417, 2010. © 2010 Wiley-Liss, Inc.
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effect of spironolactone Potassium Canrenoate and their common metabolite canrenone on serum digoxin measurement by digoxin iii a new digoxin immunoassay
Therapeutic Drug Monitoring, 2008Co-Authors: Amitava Dasgupta, Gertie Tso, Alice WellsAbstract:Abstract: Spironolactone and Potassium Canrenoate (aldosterone antagonist diuretics) are often used with digoxin in clinical practice. It has been well documented in the literature that spironolactone, Potassium Canrenoate, and their common metabolite canrenone cross-react with several digoxin immunoassays at concentrations expected after therapeutic usage of these drugs and falsely elevate or lower serum digoxin concentrations. Recently, Abbott Laboratories marketed a new Digoxin III immunoassay for application on the AxSYM analyzer. We studied the potential interference of these compounds with this new digoxin assay. The Tina-quant assay was used as the reference method because spironolactone, Potassium Canrenoate, and canrenone do not interfere with serum digoxin measurement using this assay. Aliquots of drug-free serum were supplemented with therapeutic and above therapeutic concentrations of spironolactone, canrenone, and Potassium Canrenoate, and apparent digoxin concentrations were measured using the Digoxin III assay and Tina-quant assay. Significant apparent digoxin concentrations were observed when the Digoxin III digoxin assay was used, but no apparent digoxin levels was observed using the Tina-quant assay. When serum pools prepared from patients receiving digoxin were further supplemented with these compounds in concentrations expected in sera of patients receiving these medications, falsely elevated digoxin levels were observed using Digoxin III assay, but no statistically significant change was observed using the Tina-quant assay. We conclude that spironolactone, Potassium Canrenoate, and their common metabolite canrenone interfere with the serum digoxin measurements using the new Digoxin III assay.
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a new enzyme linked chemiluminescent immunosorbent digoxin assay is virtually free from interference of spironolactone Potassium Canrenoate and their common metabolite canrenone
Journal of Clinical Laboratory Analysis, 2006Co-Authors: Amitava Dasgupta, Edward Kang, Pradip DattaAbstract:Spironolactone and Potassium Canrenoate (aldosterone antagonist diuretics) are sometimes used in conjunction with digoxin for patient management. Spironolactone, Potassium Canrenoate, and their common metabolite canrenone interfere with serum digoxin measurement using various immunoassays. Recently a new enzyme-linked chemiluminescent immunosorbent digoxin assay (ECLIA-Digoxin) became commercially available for application on the ADVIA IMS 800i modular system (Bayer HealthCare, Tarrytown, NY). We investigated the potential interference of spironolactone and related compounds in this assay by comparing the results with the fluorescence polarization immunoassay (FPIA), which is known to have significant cross-reactivity with these compounds as well as a turbidimetric assay for digoxin with no known cross-reactivity with spironolactone and related compounds. Aliquots of drug free serum were supplemented with therapeutic and above therapeutic concentrations of spironolactone, canrenone, and Potassium Canrenoate, and apparent digoxin concentrations were measured. No apparent digoxin concentration was observed using the ECLIA-Digoxin or turbidimetric assay. When serum pools prepared from patients receiving digoxin were further supplemented with these compounds, we observed no significant change in digoxin concentrations in the presence of these compounds with the ECLIA-Digoxin. We conclude that this assay is virtually free from interferences from spironolactone, Potassium Canrenoate and their common metabolite canrenone. J. Clin. Lab. Anal. 20:204–208, 2006. © 2006 Wiley-Liss, Inc.
Paolo Angeli - One of the best experts on this subject based on the ideXlab platform.
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Combined versus sequential diuretic treatment of ascites in non-azotaemic patients with cirrhosis: results of an open randomised clinical trial
Gut, 2009Co-Authors: Paolo Angeli, Silvano Fasolato, Elena Mazza, Lios Okolicsanyi, Giulio Maresio, Emanuela Velo, Alessandra Galioto, F. Salinas, Maurizio D'aquino, Antonietta SticcaAbstract:Objective: The aim of the study was to compare sequential versus combined diuretic therapy in patients with cirrhosis, moderate ascites and without renal failure. Design: One hundred patients were randomly assigned to the two diuretic treatments. The sequential treatment provided Potassium Canrenoate at the initial dose of 200 mg/day, then increased to 400 mg/day. Non-responders were treated with 400 mg/day of Potassium Canrenoate and furosemide at an initial dose of 50 mg/day, then increased to 150 mg/day. The combined treatment provided the initial dose of 200 mg/day of Potassium Canrenoate and 50 mg/day of furosemide, then increased to 400 mg/day and 150 mg/day, respectively. Results: Most patients who received sequential treatment responded to Potassium Canrenoate alone (19% to 200 mg/day and 52.63% to 400 mg/day, respectively). Most patients who received the combined treatment responded to the first two steps (40% to the first step and 50% to the second, ie, 400 mg/day of Potassium Canrenoate plus 100 mg/day of furosemide). Adverse effects (38% vs 20%, p Conclusions: The combined diuretic treatment is preferable to the sequential one in the treatment of moderate ascites in patients with cirrhosis and without renal failure. NCT00741663. This work is an open randomised clinical trial.
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randomized clinical study of the efficacy of amiloride and Potassium Canrenoate in nonazotemic cirrhotic patients with ascites
Hepatology, 1994Co-Authors: Paolo Angeli, Manuela Dalla Pria, Erica De Bei, G Albino, L Caregaro, Carlo Merkel, Giulio Ceolotto, Angelo GattaAbstract:Although some clinical studies seem to prove the efficacy of nonantialdosteronic Potassium-sparing diuretics in the treatment of ascites, no controlled study has compared the efficacy of these drugs with that of antialdosteronic diuretics. Forty nonazotemic cirrhotic patients were randomized to receive amiloride (group A, n = 20) or Potassium Canrenoate (group B, n = 20). The initial doses of amiloride and Potassium Canrenoate were 20 mg and 150 mg, respectively. The doses were increased in stepwise fashion to 60 and 500 mg/day, respectively, if no response ensued. Nonresponders to the highest doses of each drug were later treated with Potassium Canrenoate and amiloride, respectively. Seven of 20 group A patients responded to amiloride, whereas 14 of 20 group B patients responded to Potassium Canrenoate (p < 0.025). Seven of 13 nonresponders to amiloride later responded to Potassium Canrenoate, whereas only two of the nonresponders to Potassium Canrenoate later responded to amiloride. The diuretic responses to amiloride and Potassium Canrenoate were related to the activity of the renin-aldosterone system. All responders to amiloride (n = 9) had normal values of plasma aldosterone. All nonresponders to amiloride who later responded to Potassium Canrenoate (n = 7) had increased levels of plasma aldosterone. Moreover, on comparison of all responders (n = 21) and nonresponders (n = 12) to Potassium Canrenoate, a higher degree of renal proximal sodium reabsorption (with consequent limitation of sodium delivery to the distal tubule) was found to be the main difference.(ABSTRACT TRUNCATED AT 250 WORDS)
Antonietta Sticca - One of the best experts on this subject based on the ideXlab platform.
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Combined versus sequential diuretic treatment of ascites in non-azotaemic patients with cirrhosis: results of an open randomised clinical trial
Gut, 2009Co-Authors: Paolo Angeli, Silvano Fasolato, Elena Mazza, Lios Okolicsanyi, Giulio Maresio, Emanuela Velo, Alessandra Galioto, F. Salinas, Maurizio D'aquino, Antonietta SticcaAbstract:Objective: The aim of the study was to compare sequential versus combined diuretic therapy in patients with cirrhosis, moderate ascites and without renal failure. Design: One hundred patients were randomly assigned to the two diuretic treatments. The sequential treatment provided Potassium Canrenoate at the initial dose of 200 mg/day, then increased to 400 mg/day. Non-responders were treated with 400 mg/day of Potassium Canrenoate and furosemide at an initial dose of 50 mg/day, then increased to 150 mg/day. The combined treatment provided the initial dose of 200 mg/day of Potassium Canrenoate and 50 mg/day of furosemide, then increased to 400 mg/day and 150 mg/day, respectively. Results: Most patients who received sequential treatment responded to Potassium Canrenoate alone (19% to 200 mg/day and 52.63% to 400 mg/day, respectively). Most patients who received the combined treatment responded to the first two steps (40% to the first step and 50% to the second, ie, 400 mg/day of Potassium Canrenoate plus 100 mg/day of furosemide). Adverse effects (38% vs 20%, p Conclusions: The combined diuretic treatment is preferable to the sequential one in the treatment of moderate ascites in patients with cirrhosis and without renal failure. NCT00741663. This work is an open randomised clinical trial.
Alice Wells - One of the best experts on this subject based on the ideXlab platform.
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effect of spironolactone Potassium Canrenoate and their common metabolite canrenone on serum digoxin measurement by digoxin iii a new digoxin immunoassay
Therapeutic Drug Monitoring, 2008Co-Authors: Amitava Dasgupta, Gertie Tso, Alice WellsAbstract:Abstract: Spironolactone and Potassium Canrenoate (aldosterone antagonist diuretics) are often used with digoxin in clinical practice. It has been well documented in the literature that spironolactone, Potassium Canrenoate, and their common metabolite canrenone cross-react with several digoxin immunoassays at concentrations expected after therapeutic usage of these drugs and falsely elevate or lower serum digoxin concentrations. Recently, Abbott Laboratories marketed a new Digoxin III immunoassay for application on the AxSYM analyzer. We studied the potential interference of these compounds with this new digoxin assay. The Tina-quant assay was used as the reference method because spironolactone, Potassium Canrenoate, and canrenone do not interfere with serum digoxin measurement using this assay. Aliquots of drug-free serum were supplemented with therapeutic and above therapeutic concentrations of spironolactone, canrenone, and Potassium Canrenoate, and apparent digoxin concentrations were measured using the Digoxin III assay and Tina-quant assay. Significant apparent digoxin concentrations were observed when the Digoxin III digoxin assay was used, but no apparent digoxin levels was observed using the Tina-quant assay. When serum pools prepared from patients receiving digoxin were further supplemented with these compounds in concentrations expected in sera of patients receiving these medications, falsely elevated digoxin levels were observed using Digoxin III assay, but no statistically significant change was observed using the Tina-quant assay. We conclude that spironolactone, Potassium Canrenoate, and their common metabolite canrenone interfere with the serum digoxin measurements using the new Digoxin III assay.
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Bidirectional (positive/negative) interference of spironolactone, canrenone, and Potassium Canrenoate on serum digoxin measurement: elimination of interference by measuring free digoxin or using a chemiluminescent assay for digoxin.
Journal of clinical laboratory analysis, 2002Co-Authors: Amitava Dasgupta, Alice Wells, Helene Saffer, Pradip DattaAbstract:Spironolactone and Potassium Canrenoate (aldosterone antagonist diuretics) are often used with digoxin in clinical practice. Spironolactone, Potassium Canrenoate, and their common metabolite canrenone cross-react with the fluorescence polarization immunoassay (FPIA) for digoxin, and can falsely elevate serum digoxin concentrations. Serum digoxin concentrations were falsely lowered when the microparticle enzyme immunoassay (MEIA) was used. Aliquots of drug-free serum were supplemented with therapeutic and above-therapeutic concentrations of spironolactone, canrenone, and Potassium Canrenoate, and apparent digoxin activities were measured. We observed digoxin-like activities in the FPIA, but observed no activity with the MEIA or the chemiluminescent assay (CLIA). However, when serum digoxin pools prepared from patients receiving digoxin were supplemented with these compounds, we observed suppression of total digoxin levels with the MEIA. In contrast, no interference was observed in the presence of these compounds when CLIA was used for digoxin measurement. These compounds are strongly protein-bound, and no apparent digoxin activity was observed in the protein-free ultrafiltrate when drug-free sera were spiked with high levels of these compounds. Taking advantage of strong protein binding of these compounds and weak protein binding of digoxin (25%), interference of spironolactone, canrenone, and Potassium Canrenoate in FPIA and MEIA digoxin assays can be mostly eliminated by monitoring free digoxin concentration. Another approach to avoid this interference is to use the CLIA digoxin assay. © 2002 Wiley-Liss, Inc.
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bidirectional positive negative interference of spironolactone canrenone and Potassium Canrenoate on serum digoxin measurement elimination of interference by measuring free digoxin or using a chemiluminescent assay for digoxin
Journal of Clinical Laboratory Analysis, 2002Co-Authors: Amitava Dasgupta, Alice Wells, Helene Saffer, Pradip DattaAbstract:Spironolactone and Potassium Canrenoate (aldosterone antagonist diuretics) are often used with digoxin in clinical practice. Spironolactone, Potassium Canrenoate, and their common metabolite canrenone cross-react with the fluorescence polarization immunoassay (FPIA) for digoxin, and can falsely elevate serum digoxin concentrations. Serum digoxin concentrations were falsely lowered when the microparticle enzyme immunoassay (MEIA) was used. Aliquots of drug-free serum were supplemented with therapeutic and above-therapeutic concentrations of spironolactone, canrenone, and Potassium Canrenoate, and apparent digoxin activities were measured. We observed digoxin-like activities in the FPIA, but observed no activity with the MEIA or the chemiluminescent assay (CLIA). However, when serum digoxin pools prepared from patients receiving digoxin were supplemented with these compounds, we observed suppression of total digoxin levels with the MEIA. In contrast, no interference was observed in the presence of these compounds when CLIA was used for digoxin measurement. These compounds are strongly protein-bound, and no apparent digoxin activity was observed in the protein-free ultrafiltrate when drug-free sera were spiked with high levels of these compounds. Taking advantage of strong protein binding of these compounds and weak protein binding of digoxin (25%), interference of spironolactone, canrenone, and Potassium Canrenoate in FPIA and MEIA digoxin assays can be mostly eliminated by monitoring free digoxin concentration. Another approach to avoid this interference is to use the CLIA digoxin assay. © 2002 Wiley-Liss, Inc.
Pradip Datta - One of the best experts on this subject based on the ideXlab platform.
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a new enzyme linked chemiluminescent immunosorbent digoxin assay is virtually free from interference of spironolactone Potassium Canrenoate and their common metabolite canrenone
Journal of Clinical Laboratory Analysis, 2006Co-Authors: Amitava Dasgupta, Edward Kang, Pradip DattaAbstract:Spironolactone and Potassium Canrenoate (aldosterone antagonist diuretics) are sometimes used in conjunction with digoxin for patient management. Spironolactone, Potassium Canrenoate, and their common metabolite canrenone interfere with serum digoxin measurement using various immunoassays. Recently a new enzyme-linked chemiluminescent immunosorbent digoxin assay (ECLIA-Digoxin) became commercially available for application on the ADVIA IMS 800i modular system (Bayer HealthCare, Tarrytown, NY). We investigated the potential interference of spironolactone and related compounds in this assay by comparing the results with the fluorescence polarization immunoassay (FPIA), which is known to have significant cross-reactivity with these compounds as well as a turbidimetric assay for digoxin with no known cross-reactivity with spironolactone and related compounds. Aliquots of drug free serum were supplemented with therapeutic and above therapeutic concentrations of spironolactone, canrenone, and Potassium Canrenoate, and apparent digoxin concentrations were measured. No apparent digoxin concentration was observed using the ECLIA-Digoxin or turbidimetric assay. When serum pools prepared from patients receiving digoxin were further supplemented with these compounds, we observed no significant change in digoxin concentrations in the presence of these compounds with the ECLIA-Digoxin. We conclude that this assay is virtually free from interferences from spironolactone, Potassium Canrenoate and their common metabolite canrenone. J. Clin. Lab. Anal. 20:204–208, 2006. © 2006 Wiley-Liss, Inc.
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a new turbidometric digoxin immunoassay on the advia 1650 analyzer is free from interference by spironolactone Potassium Canrenoate and their common metabolite canrenone
Therapeutic Drug Monitoring, 2003Co-Authors: Pradip Datta, Amitava DasguptaAbstract:Spironolactone and Potassium Canrenoate (aldosterone antagonist diuretics) are often used with digoxin in clinical practice. It has been well documented in the literature that spironolactone, Potassium Canrenoate, and their common metabolite canrenone cross-react with the fluorescence polarization immunoassay (FPIA) for digoxin and falsely elevate measured serum digoxin concentrations. Recently a new turbidometric assay for digoxin became commercially available from Bayer Diagnostic for application on the ADVIA 1650 Chemistry analyzer. We studied the potential interference of these compounds in this new digoxin assay. Aliquots of drug-free serum were supplemented with therapeutic and above-therapeutic concentrations of spironolactone, canrenone, and Potassium Canrenoate, and apparent digoxin concentrations were measured. We observed apparent digoxin concentrations with the FPIA digoxin assay as expected but observed no apparent digoxin levels with the new turbidometric immunoassay. When serum pools prepared from patients receiving digoxin were supplemented with these compounds in concentrations expected in serum in patients receiving these medications, we observed falsely elevated digoxin levels with the FPIA digoxin assay, but no statistically significant change was observed with the new turbidometric assay. We conclude that the new turbidometric assay for digoxin is free from interference by spironolactone, Potassium Canrenoate, and their common metabolite canrenone.
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Bidirectional (positive/negative) interference of spironolactone, canrenone, and Potassium Canrenoate on serum digoxin measurement: elimination of interference by measuring free digoxin or using a chemiluminescent assay for digoxin.
Journal of clinical laboratory analysis, 2002Co-Authors: Amitava Dasgupta, Alice Wells, Helene Saffer, Pradip DattaAbstract:Spironolactone and Potassium Canrenoate (aldosterone antagonist diuretics) are often used with digoxin in clinical practice. Spironolactone, Potassium Canrenoate, and their common metabolite canrenone cross-react with the fluorescence polarization immunoassay (FPIA) for digoxin, and can falsely elevate serum digoxin concentrations. Serum digoxin concentrations were falsely lowered when the microparticle enzyme immunoassay (MEIA) was used. Aliquots of drug-free serum were supplemented with therapeutic and above-therapeutic concentrations of spironolactone, canrenone, and Potassium Canrenoate, and apparent digoxin activities were measured. We observed digoxin-like activities in the FPIA, but observed no activity with the MEIA or the chemiluminescent assay (CLIA). However, when serum digoxin pools prepared from patients receiving digoxin were supplemented with these compounds, we observed suppression of total digoxin levels with the MEIA. In contrast, no interference was observed in the presence of these compounds when CLIA was used for digoxin measurement. These compounds are strongly protein-bound, and no apparent digoxin activity was observed in the protein-free ultrafiltrate when drug-free sera were spiked with high levels of these compounds. Taking advantage of strong protein binding of these compounds and weak protein binding of digoxin (25%), interference of spironolactone, canrenone, and Potassium Canrenoate in FPIA and MEIA digoxin assays can be mostly eliminated by monitoring free digoxin concentration. Another approach to avoid this interference is to use the CLIA digoxin assay. © 2002 Wiley-Liss, Inc.
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bidirectional positive negative interference of spironolactone canrenone and Potassium Canrenoate on serum digoxin measurement elimination of interference by measuring free digoxin or using a chemiluminescent assay for digoxin
Journal of Clinical Laboratory Analysis, 2002Co-Authors: Amitava Dasgupta, Alice Wells, Helene Saffer, Pradip DattaAbstract:Spironolactone and Potassium Canrenoate (aldosterone antagonist diuretics) are often used with digoxin in clinical practice. Spironolactone, Potassium Canrenoate, and their common metabolite canrenone cross-react with the fluorescence polarization immunoassay (FPIA) for digoxin, and can falsely elevate serum digoxin concentrations. Serum digoxin concentrations were falsely lowered when the microparticle enzyme immunoassay (MEIA) was used. Aliquots of drug-free serum were supplemented with therapeutic and above-therapeutic concentrations of spironolactone, canrenone, and Potassium Canrenoate, and apparent digoxin activities were measured. We observed digoxin-like activities in the FPIA, but observed no activity with the MEIA or the chemiluminescent assay (CLIA). However, when serum digoxin pools prepared from patients receiving digoxin were supplemented with these compounds, we observed suppression of total digoxin levels with the MEIA. In contrast, no interference was observed in the presence of these compounds when CLIA was used for digoxin measurement. These compounds are strongly protein-bound, and no apparent digoxin activity was observed in the protein-free ultrafiltrate when drug-free sera were spiked with high levels of these compounds. Taking advantage of strong protein binding of these compounds and weak protein binding of digoxin (25%), interference of spironolactone, canrenone, and Potassium Canrenoate in FPIA and MEIA digoxin assays can be mostly eliminated by monitoring free digoxin concentration. Another approach to avoid this interference is to use the CLIA digoxin assay. © 2002 Wiley-Liss, Inc.