Monitorización terapéutica de la digoxina en pacientes con insuficiencia cardíaca: comparación entre dos métodos analíticos

Objective: To compare two analytical techniques used in the determination of plasma digoxin (LC-MS/MS and immunoassay) and to verify which one better answer the need of the clinical monitoring routine of patients with cardiac heart failure. Method: The clinical findings in 15 cardiac heart failure (CHF) outpatients of the Cardiac Heart Service of the Goias Federal University Clinical Hospital were investigated. Blood samples of the patients were collected and analysed by Immunoassay and by Liquid Chromatography coupled to Mass Spectrometry (LC-MS/MS). Results: The results of the statistic test (Student p = 0,05) showed a significant difference between the analytical methods: immunoassay concentrations were higher than the concentrations determined by LCMS/ MS. The explanation may be because immunoassay method measures digoxin plus other metabolites and endogenous substances, while the LC-MS/MS method measures only the digoxin molecule. None of the patients, showed relevant clinical data suggestive of digitalis intoxication, even several drugs with potential interaction were associated with treatment. Conclusion: It was concluded, therefore, that LC-MS/MS me thod is safer, more selective and specific than immunoassay, being an option for therapeutic drug monitoring of digoxin, since the reference values would be obtain for digoxinemia by LC-MS/MS.