Homogeneous Immunoassays—Therapeutic Drug Monitoring
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INNOFLUOR® Quinidine Assay System
The INNOFLUOR® QUINIDINE Assay System is intended for the quantitative determination of total quinidine in serum for therapeutic drug monitoring by fluorescence polarization immunoassay (FPIA). The assay system is for use on the TDx® or the TDxFlxTM (TDx®/TDxFLx®) analyzer.
Quinidine is an antiarrhythmic drug used in the treatment of both atrial and ventricular arrythmias.1-6 Quinidine is available for oral administration as the sulfate, gluconate, or polygluconate forms. It may also be administered intravenously by slow infusion of quinidine gluconate.1-6 Quinidine is approximately 80-90% bound to proteins in serum.3,4,7 Sixty to eighty percent of a dose is metabolized by the liver and the remainder is excreted in the urine as the unchanged drug.3,4 the elimination half-life in healthy individuals ranges from 4-10 hours.3 Principle metabolites in serum are 3-hydroxyquinidine, 2-oxoquinidine, and 0-desmethylquinidine. The 3-hydroxyquinidine metabolite is reported to have an antiarrhythmic potency similar to that of quinidine.8-10
Serum concentrations may vary widely due to individual variations in the bioavailability, metabolism, and elimination of quinidine.2,5,6,8,11-13 To achieve optimal quinidine therapy, routine monitoring of quinidine is recommended.5,14
Cohen SI. Current concepts in quinidine therapy. In: Donoso E., ed. Current cardiovascular topics, drugs in cardiology. New York, NY: Stratton International Medical Book Corp. 1975; 1: 17-35.
Woosley RL, Shand DG. Pharmacokinetics of antiarrhythmic drugs. Am J Cardiol 1978; 41: 986-995.
Anderson JL, Harrison DC, Meffin PJ, Winkle RA. Antiarrhythmic drugs: clinical pharmacology and therapeutic uses. Drugs 1978; 15: 271-309.
Harrison DC, Meffin Pj, Winkle RA. Clinical pharmacokinetics of antiarrhythmic drugs. Progr Cardiovasc Dis 1977; XX: 217-242.
Fattinger K, Vozeh S, Ha HR, Borner M, Follah F. Population pharmacokinetics of quinidine. Br J Clin Pharmac 1991; 31: 279-286.
Verme CN, Ludden TM, Clementi WA, Harris SC. Pharmacokinetics of quinidine in male patients. Clin Pharmacokinet 1992; 22(6): 468-480.
Reidenburg MM, Affrime M. Influence of disease on binding of drugs to plasma proteins. Ann NY Acad Sci 1973; 226: 115-126.
Drayer DE, Lowenthal DT, Restivo KM, Schwartz A, Cook T, Reidenburg MM. Steady state serum levels of quinidine and active metabolites in cardiac patients with varying degrees of renal function. Clin Pharmacol Ther 1978; 24: 31-39.
Drayer DE, Cook CE, Reidenburg MM. Active quinidine metabolites. Clin Res 1976; 24: 623A.
Ueda CT, Williamson BJ, Dzindzio BS. Disposition kinetics of dihydroquinidine following quinidine administration. Res Commun Chem Pathol Pharmacol 1976; 14: 215-225.
Guentert TW, Holford NG, Coates PE, Upton RA, Riegelman S. Quinidine pharmacokinetcics in man: choice of a disposition model and absolute bioavailability studies. J Pharmacokinetic Biopharm 1979; 7: 315-330.
Mason DT, et al. Antiarrhythmic agents: mechanism of action, clinical pharmacology and therapeutic considerations. In: Graeme, SA ed. Cardiovascular drugs. Baltimore, MD: University Park Press, 1978; 1: 75-127.
Moyer TP. Practical therapeutic drug monitoring. In: Hornburger HA, Batsakis JG eds. Clin Lab Ann, Norwalk, CT: Appleton, Century, Crofts, 1982; 2: 279-332.
