European Journal of Pharmaceutical Sciences 12 (2000) 85–93 www.elsevier.nl / locate / ejps In vitro and in vivo investigations on fluoroquinolones; effects of the P-glycoprotein efflux transporter on brain distribution of sparfloxacin a, b a * Elizabeth C.M. de Lange , Sandrine Marchand , Dirk-Jan van den Berg , Inez C.J. van der a a b b b Sandt , Albertus G. de Boer , Annie Delon , Serge Bouquet , William Couet a Leiden / Amsterdam Center for Drug Research, Division of Pharmacology, Sylvius Laboratory, Leiden University, P .O. Box 9503, 2300 RA Leiden, The Netherlands b UPRES EA12-23, Centre de Recherche des Xenobiotiques, Faculte de Pharmacie, 34 Rue du Jardin des Plantes, BP 199, 86005 Poitiers Cedex, France Received 6 March 2000; received in revised form 30 June 2000; accepted 30 June 2000 Abstract The role of mdr1a-encoded P-glycoprotein on transport of several fluoroquinolones across the blood–brain barrier was investigated. In vitro, P-glycoprotein substrates were selected by using a confluent monolayer of MDR1-LLC-PK1 cells. The inhibition of fluoro- quinolones (100 mM) on transport of rhodamine-123 (1 mM) was compared with P-glycoprotein inhibitors verapamil (20 mM) and SDZ PSC 833 (2 mM). Subsequently, transport polarity of fluoroquinolones was studied. Sparfloxacin showed the strongest inhibition (26%) and a large polarity in transport, by P-glycoprotein activity. In vivo, using mdr1a ( 2 / 2) and wild-type mice, brain distribution of pefloxacin, norfloxacin, ciprofloxacin, fleroxacin and sparfloxacin was determined at 2, 4, and 6 h following intra-arterial infusion (50 nmol/min). Brain distribution of sparfloxacin was clearly higher in mdr1a ( 2 / 2) mice compared with wild-type mice. Sparfloxacin was infused (50 nmol / min) for 1, 2, 3 and 4 h in which intracerebral microdialysis was performed. At 4 h, in vivo recovery (dynamic-no-net-flux method) was 6.562.2 and 1.560.5%; brain concentrations were 5.160.2 and 26621 mM; and total brain ECF concentrations were 7.260.3 and 2360.3 mM in wild-type and mdr1a ( 2 / 2) mice, respectively. Plasma concentrations were similar (18.460.7 and 17.960.5 mM, respectively). In conclusion, sparfloxacin enters the brain poorly mainly because of P-glycoprotein activity at the blood–brain barrier.  2000 Elsevier Science B.V. All rights reserved. Keywords: Intracerebral microdialysis; Blood–brain barrier; mdr1a (2 / 2) mice; In vivo recovery; Dynamic-no-net-flux; Fluoroquinolones; P-Glycopro- tein; Sparfloxacin; In vitro transport; LLC-PK1 cells 1. Introduction other hand, severe CNS side effects like hallucinations, anxiety, agitation, depression, and convulsions have been Fluoroquinolones are used in the chemotherapy of reported following administration of fluoroquinolones various infectious diseases because of their broad and (Ooie et al., 1997a), probably related to their penetration strong antibacterial activity, especially against Gram-nega- into the brain since seizures have been shown to be related tive bacteria (Moellering, 1996). Fluoroquinolones tend to to CSF concentrations in laboratory animals (Delon et al., distribute rapidly into peripheral tissues and fluids, and 1997, 1998) reach concentrations often higher than found in serum or For optimal therapy, knowledge of factors involved in ¨ plasma (Sorgel et al., 1989). However, distribution of the the transport of fluoroquinolones into the brain should be unbound drugs into the cerebrospinal fluid (CSF) and brain known. Transport into the brain is to a large extent extracellular fluid (brain ) was shown to be poor determined by transport across the blood–brain barrier. ECF (Kitzes-Cohen, 1989; Ooie et al., 1996a, 1997a). On the Blood–brain barrier transport of fluoroquinolones has been studied in vitro (Jaehde et al., 1993), and in vivo (Ooie et al., 1996a, 1997a,b) where mostly transport into the CSF was investigated (Jaehde et al., 1992; Ooie et al., 1996b,c; *Corresponding author. Tel.: 131-71-5276-330 / 6211; fax: 131-71- Delon et al., 1999). These studies indicated that dis- 5276-292 / 70-5141260. E-mail address: l.lange@chem.leidenuniv.nl (E.C.M. de Lange). tribution of fluoroquinolones into the brain was restricted, 0928-0987 / 00 / $ – see front matter  2000 Elsevier Science B.V. All rights reserved. PII: S0928-0987(00)00149-4