Short Communication THE ANTHELMINTHIC AGENT ALBENDAZOLE DOES NOT INTERACT WITH P-GLYCOPROTEIN

Albendazole is a clinically important anthelminthic agent known to have variable and low oral bioavailability. The aim of this work was to determine whether albendazole, a CYP3A4 substrate, is also a substrate for the multidrug efflux transporter P-glycoprotein. Both in vitro and in vivo methods were used to assess the role of P-glycoprotein-mediated albendazole transport. In cultured LLCPK1, L-MDR1, and Caco-2 cells, albendazole was found not to be a P-glycoprotein substrate; the transport across LLC-PK1 and L-MDR1 cells revealed basal to apical versus apical to basal transport to a similar extent. In addition, there was no inhibitory effect of albendazole on digoxin transport in Caco-2 cells, and P-glycoprotein inhibitors (verapamil and quinidine) did not affect transport across Caco-2 cells. The in vivo relevance of P-glycoprotein to albendazole disposition was assessed using mdr1a/1b( / ) mice after intravenous administration of albendazole (15 mg/kg). A similar pattern of tissue distribution in both P-glycoprotein-deficient and wild-type mice was observed. In conclusion, albendazole is neither a substrate nor an inhibitor of P-glycoprotein. Therefore, interactions between albendazole and P-glycoprotein substrates or inhibitors are unlikely to be clinically important. Albendazole (ABZ) is a broad-spectrum anthelminthic agent (Bennett and Guyatt, 2000; Cox, 2000) also used to treat microsporidial infections, an emerging disease of relevance, particularly among those infected with human immunodeficiency virus (Costa and Weiss, 2000). ABZ is converted in vivo into albendazole sulfoxide (ABZSO) and albendazole sulfone (ABZSO2). CYP450 and the flavin monooxygenase system have been suggested to be responsible for the sequential sulfoxidation of ABZ. Both systems are involved in the sulfoxidation (Rawden et al., 2000), whereas CYP450 is the main determinant of sulfonation (Souhaili-El Amri et al., 1988). Involvement of the two pathways in ABZ metabolism has been observed in several animal species (Galtier et al., 1986; Souhaili-El Amri et al., 1988) and among humans (Rolin et al., 1989). Moreover, intestinal metabolism and significant secretion of ABZSO into the intestinal lumen have also been demonstrated (Redondo et al., 1999). Recent data suggest CYP3A4 may be the key contributor of ABZSO formation (Rawden et al., 2000). ABZ therapy is in hampered by its low solubility and poor absorption from the gastrointestinal tract, resulting in low bioavailability and reduced efficacy. In addition to its physicochemical properties, active transport by efflux pumps such as P-glycoprotein (P-gp), a product of the multidrug resistance gene MDR1, may have a role in ABZ disposition. P-gp is expressed in organ systems that influence drug absorption (intestine), distribution (central nervous system, leukocytes, and testes), and elimination (liver and kidney) (Cordon-Cardo et al., 1989; Tsuji et al., 1992). Moreover, P-gp is known to be coexpressed with CYP3A4, the key CYP450 involved in the metabolism of many drugs including ABZ, in organs such as the intestine and liver (Maurel, 1996). In addition, P-gp and CYP3A4 share many substrates and inhibitors (Wacher et al., 1995). Accordingly, a systematic study was undertaken to determine the extent of P-gp involvement in ABZ transport both in vitro and in vivo. Materials and Methods Chemicals. [H]digoxin was obtained from PerkinElmer Life Sciences (Boston, MA) and [C]ABZ from GlaxoSmithKline (Madrid, Spain). ABZ, ABZSO, and ABZSO2 were supplied by GlaxoSmithKline. Mebendazole, verapamil, quinidine, and probenecid were purchased from Sigma Chemical Co. (St. Louis, MO). Methanol and acetic acid were obtained from Merck (Darmstadt, Germany), acetonitrile from BDH (Poole, UK), and ethyl acetate from Sigma-Aldrich (Dorset, UK). Transport in Cultured LLC-PK1, L-MDR1, and Caco-2 Cells. LLCPK1 and L-MDR1 (LLC-PK1 cells transfected with MDR1 cDNA and stably expressing human MDR P-gp) were grown under identical conditions to those described by Schinkel et al. (1995). Caco-2 cells were grown under the same conditions previously described (Kim et al., 1998). Transport experiments were carried out using the same protocol described previously (Kim et al., 1998). ABZ transport in L-MDR1 and LLC-PK1 cells was measured using five different concentrations (6.25, 12.5, 25, 50, and 100 M) of [C]ABZ, and four concentrations (6.25, 12.5, 25, and 50 M) were tested in Caco-2 cells. In addition, at the end of each experiment, filters containing the cells were washed three times with cold Dulbecco’s modified Eagle’s medium, and the radioactivity was measured. Radiolabeled digoxin was used as a control P-gp substrate. Inhibition of P-gp-mediated transport by Caco-2 cells was determined in a This work was supported by a United States Public Health Service (USPHS) Grant GM31304 and GM54724 and Grant PN98 9789011G (to G.M.) from Ministry of Science and Technology (Spain), Plan Nacional de Formacion de Personal Investigador. 1 Abbreviations used are: ABZ, albendazole; ABZSO, albendazole sulfoxide; ABZSO2, albendazole sulfone; P-gp, P-glycoprotein; MDR, multidrug resistance; HPLC, high-pressure liquid chromatography; cMOAT, canalicular multispecific organic anion transporter. Address correspondence to: Dr. Richard B. Kim, 572 MRB1, Division of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232-6602. E-mail: [email protected] 0090-9556/02/3004-365–369$7.00 DRUG METABOLISM AND DISPOSITION Vol. 30, No. 4 Copyright © 2002 by The American Society for Pharmacology and Experimental Therapeutics 605/973886 DMD 30:365–369, 2002 Printed in U.S.A. 365 at A PE T Jornals on Jne 2, 2017 dm d.aspurnals.org D ow nladed from