Determination of deferiprone in urine and serum using a terbium-sensitized luminescence method Jamshid L. Manzoori, a Mohammad Amjadi, a Jafar Soleymani, b Elnaz Tamizi, c Azim Rezamand d and Abolghasem Jouyban e * ABSTRACT: Optimized conditions, validation and practical applications of a new, rapid and specific fluorometric method for the determination of deferiprone (DFP) in urine and serum samples are reported. The proposed method, which is based on the formation of a luminescent complex with Tb 3+ ion, is evaluated in terms of linearity, accuracy, precision, stability, recov- ery and limits of detection (LOD) and quantification (LOQ). Under optimum conditions (pH 7.5, [Tb 3+ ]=3  10 –4 mol/L, tem- perature 0  C and excitation wavelength 295 nm), the relative intensities at 545 nm are linear, with the concentration of DFP in the range 0.072–13 mmol/L for urine and serum samples. The LOD and LOQ, respectively, are calculated to be 0.014 and 0.045 mmol/L for urine and 0.022 and 0.072 mmol/L for serum samples. The intra-day and inter-day values for the preci- sion and accuracy of the proposed method are all < 5%, and the recovery of the method is in the range 97.1–103.8%. The method was applied to human urine and serum samples collected from patients receiving DFP. The results indicated that the method can be successfully applied to the determination of DFP in human urine and serum samples collected for clinical or biopharmaceutical investigations in which simple, rapid, cheap and specific determination methods facilitate and speed up the analytical procedure. Copyright © 2011 John Wiley & Sons, Ltd. Keywords: terbium-sensitized; deferiprone; serum; urine; fluorometric method Introduction Iron overload due to chronic transfusion therapy causes organ damage; therefore, chelators of iron, such as deferiprone (DFP), should be used to remove excess iron from various parts of the body. DFP (1,2-dimethyl-3-hydroxypyridin-4-one) (with a molecular weight 139.15 g/mol) is an active iron chelator and superoxide-radical scavenger, and belongs to the new class of chelating agents, a-ketohydroxypyridines. DFP, the first oral iron chelator, is prescribed mainly in b-thalassaemia minor, Cooley’ s anaemia and hereditary haemochromatosis. It is also indicated in treating cancer and haemodialysis. DFP can inhibit DNA synthesis and therefore can be used as anti-HIV replication drug; in addition, it is a potent chelator of iron in the mitochon- drial matrix and can be applied for treatment of Friedreich’ s ataxia (1–7). To maintain a negative iron balance in overloaded patients, DFP must be administered at a high daily dosage of 75 mg/kg (8). The limited efficiency of DFP is mainly due to extensive phase II drug metabolism in the liver, where the hydroxyl group – essential for chelation and iron clearance – undergoes glucur- onidation (9). Arthropathy and neutropenia are very frequent side-effects of DFP and need strict monitoring during therapy. Most of the neutropenia cases are neither very severe nor do they recur with a rechallenge with the drug. Similarly, arthropa- thy does not need withdrawal of the drug in the majority of the patients (10). In a pharmacokinetic study in humans, the plasma concentra- tion of DFP was reported to vary from 25 μmol/L (12 min after oral administration of 3 g DFP) to 450 μmol/L (30 min after the same dose) (11). The maximum reported concentration of DFP excreted in urine was 306.1  67.6 μmol/L, observed 3 h after ad- ministration of a single dose of 500 mg. The average excretion rate was 0.0001 μmol/min/kg at 24 h after drug administration. Abbas et al. (12) reported that 2.7% of DFP is excreted in urine and a plasma concentration of 23.2  1.9 μmol/L is obtained af- ter oral administration of 500 mg DFP. The daily dose of DFP needed to treat iron overload is 2–3 g every 6 h (11). Complexes of trivalent lanthanide ions, especially terbium, with appropriate ligands have attracted more attention in recent years because the specific physicochemical properties of this ion, as a result of its electronic structure, make it useful for probes and sensors in the chemical and medical sciences. The electron transition in the 4f shells is responsible for the narrow * Correspondence to: A. Jouyban, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz 51664, Iran. E-mail: ajouyban@hotmail.com a Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Iran b Haematology–Oncology Research Centre, Tabriz University of Medical Sciences, Iran c Liver and Gastrointestinal Diseases Research Centre, Tabriz University of Medical Sciences, Iran d Department of Paediatrics, Faculty of Medicine, Tabriz University of Medical Sciences, Iran e Drug Applied Research Centre and Faculty of Pharmacy, Tabriz University of Medical Sciences, Iran Luminescence 2012; 27: 268–273 Copyright © 2011 John Wiley & Sons, Ltd. Research article Received: 29 May 2011, Accepted: 06 July 2011, Published online in Wiley Online Library: 18 August 2011 (wileyonlinelibrary.com) DOI 10.1002/bio.1344 268