Risk factors for aerobic bacterial conjunctival flora in preoperative cataract patients.

PurposeTo investigate the relationship between the background of preoperative cataract patients and bacterial conjunctival flora.MethodsA total of 990 cataract patients who had completed preoperative examinations in 2007 and 2008 were included. Patients using topical antibiotics at the preoperative examination or having a history of intraocular surgery were excluded. Conjunctival cultures had been preoperatively obtained. Patient characteristics were investigated via medical records. Risk factors for conjunctival flora of seven typical bacteria were analyzed by univariate and multivariate analyses.ResultsThe detection rate of alpha-hemolytic streptococci and Enterococcus faecalis increased with age (P=0.044 and P=0.002, respectively). The detection rate of Gram-negative bacilli was higher among patients with oral steroid use or lacrimal duct obstruction (P=0.038 and P=0.002, respectively). The detection rate of Corynebacterium species was higher among older patients and men, and lower among patients with glaucoma eye drop use (P<0.001, P=0.012 and P=0.001, respectively). The detection rate of methicillin-susceptible coagulase-negative Staphylococci was higher among men and lower among patients with a surgical history in other departments (P=0.003 and P=0.046, respectively). The detection rate of methicillin-resistant coagulase-negative Staphylococci (MR-CNS) was higher among patients with oral steroid use, a visit history to ophthalmic facilities, or a surgical history in other departments (P=0.002, P=0.037 and P<0.001, respectively).ConclusionsElderly patients, men, patients with lacrimal duct obstruction or immunosuppressed patients are more likely to be colonized by pathogens that cause postoperative endophthalmitis. Moreover, MR-CNS colonization was associated with healthcare-associated infection.

Enhancement of gene expression by transcriptional activation using doxorubicin-loaded liposome/pDNA complexes.

Gene therapy is a promising treatment option for cancers generated by mutation of oncogenes or tumor suppressor genes. The transcriptional process is activated by doxorubicin (DXR), and gene expression efficiency followed by gene transfection can be enhanced by the combination-use of DXR. Therefore, co-encapsulation of plasmid DNA (pDNA) and DXR into non-viral gene carriers can enhance gene expression. Here, we prepared DXR-loaded liposome/pDNA complexes (DXR-loaded PEGylated lipoplexes) by co-encapsulating pDNA and DXR into liposomes. Gene expression was enhanced by DXR encapsulation into lipoplexes in colon-26 cells and cultured mouse macrophages, and this gene expression level was significantly higher than that obtained by the combination of PEGylated lipoplexes and free DXR. Moreover, the activation profiles of transcriptional factors induced by DXR-loaded lipoplexes were different from those induced by free DXR; therefore, co-encapsulation of pDNA and DXR into gene carriers might be contributed to effective enhancement of gene expression. These findings provide a new approach for achieving effective gene transfection using PEGylated lipoplexes.

Enhanced growth inhibition of metastatic lung tumors by intravenous injection of ATRA-cationic liposome/IL-12 pDNA complexes in mice.

Interleukin 12 (IL-12) is a proinflammatory cytokine with antitumor activity. All-trans-retinoic acid (ATRA) exerts antitumor effects by regulating a variety of gene expressions, including tumor necrosis factor receptor 1 (TNFR1), increases the number of TNFR1 and potentiates TNF-alpha-induced apoptosis in cancer cells. In this study, ATRA-incorporated cationic liposome (ATRA-cationic liposome)/IL-12 plasmid DNA (pDNA) complexes were prepared to improve therapeutic efficacy of cationic liposome/IL-12 pDNA complexes in a mouse model of metastatic lung tumor after intravenous injection. IL-12 production in lungs by ATRA-cationic liposome/IL-12 pDNA complexes was comparable with that by cationic liposome/IL-12 pDNA complexes. The number of metastatic tumor cells (colon26/Luc) was quantitatively evaluated by measuring luciferase activity. ATRA-cationic liposome/IL-12 pDNA complexes reduced the number of colon26/Luc cells and tumor nodules in lungs. ATRA-cationic liposome/IL-12 pDNA complexes significantly prolonged the survival time of mice, whereas cationic liposome/IL-12 pDNA only slightly prolonged it. ATRA-cationic liposome/IL-12 pDNA complexes increased the TNFR1 mRNA upregulation and the number of apoptotic cells in the lung. Moreover, reduced serum alanine transaminase (ALT) and aspartate transaminase (AST) activities were observed in mice treated with ATRA-cationic liposome/IL-12 pDNA complexes. These results suggest that intravenous injection of ATRA-cationic liposome/IL-12 pDNA complexes is an effective method for the treatment of lung metastasis in mice.

Non-thermal ablation of expanded polytetrafluoroethylene with an intense femtosecond-pulse laser.

Ablation of expanded polytetrafluoroethylene without disruption of the fine porous structure is demonstrated using an intense femtosecond-pulse laser. As a result of laser-matter interactions near ablation threshold fluence, high-energy ions are emitted, which cannot be produced by thermal dissociation of the molecules. The ion energy is produced by Coulomb explosion of the elements of (-CF(2)-CF(2)-)(n) and the energy spectra of the ions show contributions from the Coulomb explosions of the ions rather than those of thermal expansion to generate high-energy ions. The dependence of ion energy on the laser fluence of a 180-fs pulse, compared with that of a 400-ps pulse, also suggests that the high-energy ions are accelerated by Coulomb explosion.

Combining cisplatin with cationized catalase decreases nephrotoxicity while improving antitumor activity.

Cisplatin is frequently used to treat solid tumors; however, nephrotoxicity due to its reactive oxygen species-mediated effect limits its use. We tested the ability of cationized catalase, a catalase derivative, to inhibit nephrotoxicity in cisplatin-treated mice. Immunohistochemical analysis showed that the catalase derivative concentrated in the kidney more efficiently than native catalase. Repeated intravenous doses of cationized catalase significantly decreased cisplatin-induced changes in serum creatinine, blood urea nitrogen, nitrite/nitrate levels, lactic dehydrogenase activity, and renal total glutathione and malondialdehyde contents. In addition, cationized catalase effectively blunted cisplatin-induced proximal tubule necrosis but had no significant effect on the cisplatin-induced inhibition of subcutaneous tumor growth. Repeated doses of catalase, especially cationized catalase, significantly increased the survival of cisplatin-treated tumor-bearing mice preventing cisplatin-induced acute death. Our studies suggest that catalase and its derivatives inhibit cisplatin-induced nephrotoxicity, thus improving the efficiency of cisplatin to treat solid tumors.

Physicochemical and pharmacokinetic characteristics of cationic liposomes.

After intravenous administration of plasmid DNA (pDNA)/cationic liposome complexes, the gene expression is predominantly observed in the lung due to the physicochemical properties of the liposome complexes and the physiology of the lung. To determine the physicochemical properties and distribution behavior of cationic liposomes for lung-selective drug and/or gene delivery systems, N-[1-(2,3-dioleyloxy)propyl]-n,n,n-trimethylammonium chloride (DOTMA)/cholesterol and 1,2-dioleoyl-3-trimethyl-ammoniopropane (DOTAP)/cholesterol liposomes were studied. The particle sizes of DOTMA/cholesterol and DOTAP/cholesterol liposomes were very similar: 126 and 128 nm, respectively. Furthermore, the zeta potentials of these two liposomes were 51 and 66 mV, respectively. After intravenous injection into mice, both cationic liposomes were rapidly eliminated from the blood circulation and preferentially recovered in the lung. Interestingly, the highest lung accumulation was observed at 1 min, and then, decreased gradually. The distribution characteristics of DOTMA/cholesterol and DOTAP/cholesterol liposomes were almost identical due to the similarities in their physicochemical properties. These results demonstrated that DOTMA/cholesterol and DOTAP/cholesterol liposomes, which possess a positive charge, are promising carriers for lung-selective drug and/or gene delivery systems.

Suppression of TNFalpha production in LPS induced liver failure in mice after intravenous injection of cationic liposomes/NFkappaB decoy complex.

NFkappaB decoy, double stranded oligonucleotides containing NFkappaB binding sequences, inhibits NFkappaB-mediated production of inflammatory cytokines, and therefore NFkappaB decoy has been applied to several diseases. However, naked NFkappaB decoy, which is quickly cleared from the circulation in mice after intravenous injection, is readily absorbed into the systemic circulation. In order to deliver enough NFkappaB decoy for a therapeutic effect, it is necessary to develop a carrier, which enables much more NFkappaKB decoy to transfer to the target cells. In this study, using N-[1-(2,3-dioleyloxy)propyl]-n,n,n-trimethylammonium chloride (DOTMA)/cholesterol (1 :1) liposomes, the therapeutic effect of NFkappaB decoy was investigated in an LPS induced acute hepatitis model mice. The mean diameter of the cationic liposomes/NFkappaB decoy complex was about 70.9 nm and the zeta potential of complex was about 37.4 mV. Tissue distribution was determined by measuring the radioactivity of a cationic liposomes/ [32P] NFkappaB decoy complex after intravenous injection. The cationic liposomes/[32P] NFkappaB decoy complex was rapidly accumulated in the lung and gradually moved to the liver. The therapeutic effect was determined by the serum concentration of TNFalpha in LPS treated mice. The production of TNFalpha was significantly inhibited by cationic liposomes/NFkappaB decoy complex but not by cationic liposomes/random decoy complex or naked NFkappaB decoy. These results suggested that NFkappaB decoy therapy could be achieved using cationic liposomes. This information is of great value for the design of NFkappaB decoy carrier systems.

Inhibitory effects of safe and novel SOD derivatives, galactosylated-SOD, on hepatic warm ischemia/reperfusion injury in pigs.

BACKGROUND/AIMS: Oxygen-derived free radicals such as superoxide play an important role in ischemia/reperfusion (IR) injury during and after extensive liver surgery or liver transplantation. Superoxide dismutase (SOD) has protective effects against hepatic IR injury. The effect of native SOD is, however, limited because of rapid elimination from the blood circulation and poor affinity for liver cells. It was reported by our collaborators that a SOD derivative modified with galactose (Gal-SOD) was selectively delivered well to hepatocytes by direct attachment to galactose receptors. In the present study, the efficacy of this agent for attenuating hepatic warm IR injury was investigated using the pig model. METHODOLOGY: After 45-min clamping of the hepatic artery and portal vein, pigs were divided into 3 groups according to the following treatments. Ten milliliters of normal saline in Group 1 (n=5), 10,000 units/kg of native SOD in Group 2 (n=5) and 10,000 units/kg of Gal-SOD in Group 3 (n=5) were given just prior to hepatic reperfusion. Liver function including clearance of total bile acid (TBA) and hyaluronic acid (HA) was investigated. Lipid peroxidase of the liver tissue (LPO) and histological findings were examined. In addition, survival rates of the pigs in each group were evaluated. RESULTS: The survival rates at the 7th day after the operation were 60%, 80%, 100% in Groups 1, 2 and 3, respectively. Liver function tests, clearance of TBA and HA, and LPO levels were significantly improved in Groups 3 over findings in Groups 1 and 2. Congestion of hepatic tissues and vacuolization of hepatocytes in Group 3 were less than those in Groups 1 and 2. These results suggested that oxygen-derived free radicals were scavenged by Gal-SOD and IR injury was attenuated. CONCLUSIONS: A safe and novel agent, Gal-SOD has a protective effect against hepatic warm IR injury.

Hepatocyte-targeted gene transfer by combination of vascularly delivered plasmid DNA and in vivo electroporation.

To increase transgene expression in the liver, electric pulses were applied to the left lateral lobe after intravenous injection of naked plasmid DNA (pDNA) or pDNA/liver targeting vector complex prepared with galactosylated poly(L-lysine) or galactosylated polyethyleneimine. Electroporation (250 V/cm, 5 ms/pulse, 12 pulses, 4 Hz) after naked pDNA injection dramatically increased the expression up to 200,000-fold; the expression level obtained was significantly greater than that achieved by the combination of pDNA/vector complex and electroporation. We clearly demonstrated that the expression was dependent on the plasma concentration of pDNA at the time when the electric pulses were applied. Separation of liver cells revealed that the distribution of naked pDNA as well as transgene expression was largely selective to hepatocytes in the electroporated lobe. The number of cells expressing transgene product using vascularly administered naked pDNA followed by electroporation was significantly (P<0.01) greater and more widespread than that obtained by local injection of naked pDNA. These results indicate that the application of in vivo electroporation to vascularly administered naked pDNA is a useful gene transfer approach to a large number of hepatocytes.

Effect of cationic charge on receptor-mediated transfection using mannosylated cationic liposome/plasmid DNA complexes following the intravenous administration in mice.

The purpose of this study was to evaluate the effect of cationic charge of complexes after intravenous administration of cholesten-5-yloxy-N-[4-[(1-imino-2-D-thiomannosyl-ethyl)amino]butyl]formamide (Man-C4-Chol) containing cationic liposomes/pDNA complexes in mice. Transfection efficiency after intravenous administration of complex at a charge ratio (- : +) of 1.0:2.3 and/or 1.0:3.1 in liver and spleen expressing a mannose receptor on the cell surface were higher than those in lung. When complexes were formed at a charge ratio (- : +) of 1.0:4.7, on the other hand, transfection efficiency in the lung was highest, suggesting a non-specific interaction. Although asialoglycoprotein receptors are expressed on hepatocytes, a liver-selective gene transfection was not achieved by the intravenous administration of pDNA complexed with cholesten-5-yloxy-N-[4-[(1-imino-2-D-thiogalactosyl-ethyl)-amino]butyl]formamide (Gal-C4-Chol)/DOPE liposomes at a charge ratio (- : +) of 1.0 : 2.3. This information supports the design of pDNA/ligands-grafted cationic liposome complexes for cell-specific gene delivery after intravenous administration.

Ion generation in a low-density plastic foam by interaction with intense femtosecond laser pulses.

Energetic proton generation in low-density plastic (C5H10) foam by intense femtosecond laser pulse irradiation has been studied experimentally and numerically. Plastic foam was successfully produced by a sol-gel method, achieving an average density of 10 mg/cm(3). The foam target was irradiated by 100 fs pulses of a laser intensity 1 x 10(18) W/cm(2). A plateau structure extending up to 200 keV was observed in the energy distribution of protons generated from the foam target, with the plateau shape well explained by Coulomb explosion of lamella in the foam. The laser-foam interaction and ion generation were studied qualitatively by two-dimensional particle-in-cell simulations, which indicated that energetic protons are mainly generated by the Coulomb explosion. From the results, the efficiency of energetic ion generation in a low-density foam target by Coulomb explosion is expected to be higher than in a gas-cluster target.

The role of tissue macrophages in the induction of proinflammatory cytokine production following intravenous injection of lipoplexes.

Recent studies have demonstrated that intravenous administration of a plasmid DNA-cationic liposome complex (lipoplex) induced significant proinflammatory cytokine production in blood and inhibited transgene expression in pulmonary endothelial cells. In this study, we examined the effects of gadolinium chloride (GdCl(3)) pretreatment on the biodistribution and induction of proinflammatory cytokine production and transgene expression after intravenous injection of a lipoplex in mice. GdCl(3) is known to transiently deplete liver Kupffer cells and spleen macrophages after intravenous administration. Intravenous administration of a lipoplex triggers high levels of proinflammatory cytokine production, such as TNF-alpha, IFN-gamma and IL-12 in serum and a large amount of (32)P-labeled lipoplex accumulates in the liver 1 h after intravenous administration. However, pretreatment with GdCl(3) dramatically reduces serum levels of these cytokines and liver accumulation of the lipoplex. RT-PCR analysis showed that mRNA expression of TNF-alpha greatly increases in the liver and spleen after lipoplex injection and that pretreatment with GdCl(3) reduces mRNA expression in these organs. Messenger RNA expression of TNF-alpha in the liver occurs in non-parenchymal cells (sinusoidal endothelial cells and/or Kupffer cells). Inhibition of cytokine production by pretreatment with GdCl(3) leads to recovery of transgene expression in the lung following the second injection of lipoplex, which was reduced following the first injection of lipoplex. Thus, the present study demonstrates that tissue macrophages involving liver Kupffer cells and spleen macrophages are closely involved in TNF-alpha production following i.v. administration of the lipoplex. It is also suggested that avoiding lipoplex uptake and subsequent cytokine production by these cells would be a useful method of maintaining a high level of gene expression in the lung after repeated injections.

Serum mannan binding protein inhibits mannosylated liposome-mediated transfection to macrophages.

The effects of serum mannan binding proteins (MBP) in the transfection of plasmid DNA/Man-liposome complex via mannose receptor-mediated endocytosis was studied in vitro using cultured mouse peritoneal macrophages. Plasmid DNA encoding luciferase gene was complexed with cationic mannosylated liposomes (Man-liposomes), composed of cholesten-5-yloxy-N-(4-((1-imino-2-D-thiomannosylethyl)amino)alkyl)formamide (Man-C4-Chol) and dioleoyl phosphatidylethanolamine (DOPE). The transfection efficiency, as well as the binding and uptake of the plasmid DNA/Man-liposome complex, was investigated with or without serum MBP. The in vitro transfection efficiency of the complex was significantly reduced on increasing the amount of serum MBP. In addition, the cellular association of the complex was also reduced. These results indicate that serum MBP specifically binds to the mannose moieties on the complex and suppresses its cellular uptake, resulting in inhibition of the gene transfection in macrophages. Such an interaction is an obstacle to mannose receptor-mediated in vivo gene transfer to mannose receptor-positive cells using mannosylated gene carriers.

Quantitative structure/property relationship analysis on aqueous solubility using genetic algorithm-combined partial least squares method.

The present study was initiated to generate a model of predicting aqueous solubility of substances from their molecular structure. For 211 drugs or drug-like compounds, their topological indices were calculated by Molconn-Z software. The optimal subset of the descriptors for the prediction of aqueous solubility was determined by genetic algorithm in combination with partial least squares (PLS) method. Thirty-four descriptors were selected by this method. Using 29 of the descriptors selected, of which the scaled PLS coefficient was significant, the cross-validated predictive q2 was 0.785 with 19 principal components that was the optimal and the standard error of prediction was 0.676. Thus, it is suggested that the model obtained would exhibit a good performance in predicting the aqueous solubility of compounds.

Surface hydrophobicity of particles is not necessarily the most important determinant in their in vivo disposition after intravenous administration in rats.

The in vivo disposition of polystyrene microsphere (MS) with the particle size of 50 nm (MS-50) and lecithin-coated MS-50 (LMS-50) after intravenous administration to rats was characterized. While a rapid elimination from the systemic circulation was observed for MS-50, much more prolonged circulating property was observed for LMS-50. In addition, this in vivo disposition property of LMS-50 was suggested to be ascribed to its lower affinity to the liver, which is the determining organ of the in vivo disposition of MS-50. The evaluation of surface hydrophobicity of MS-50 and LMS-50 in buffer solution revealed that the surface of MS-50 is more hydrophobic than that of LMS-50. However, LMS-50 was oppositely found to be more hydrophobic than that of MS-50 in rat serum. The profiles of serum proteins associated with MS-50 and LMS-50 were also examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The results showed that the amounts of some adsorbed proteins are greatly different between MS-50 and LMS-50. From these findings, it was suggested that the substantial difference in the in vivo disposition between MS-50 and LMS-50 would not be attributed to the difference in their surface hydrophobicity in the blood, but the difference in the type of serum proteins associated with them.

Synthesis and pharmacological activity of a novel water-soluble hepatocyte-specific polymeric prodrug of prostaglandin E(1) using lactosylated poly(L-glutamic hydrazide) as a carrier.

A novel polymeric prodrug of prostaglandin E(1) (PGE(1)) was synthesized using lactosylated poly(L-glutamic hydrazide) (Lac-NH-PLGA) as a targetable carrier to hepatocytes. Poly(L-glutamic hydrazide) (PLGA-HZ) was prepared by reacting poly(gamma-benzyl-L-glutamate) with hydrazine monohydrate, followed by coupling with lactose via a hydrazone linkage. Then the lactosylated PLGA-HZ was reduced by sodium cyanoborohydride (NaBH(3)CN) in order to make the linkage irreversible (Lac-NH-PLGA). Finally, PGE(1) was bound to hydrazide moieties remaining in Lac-NH-PLGA without any condensing agent under weakly acidic conditions (pH 5) where PGE(1) would be chemically most stable at room temperature (PGE(1) conjugate). The PGE(1) conjugate prepared was sufficiently water-soluble in spite of the hydrophobic nature of its backbone (-NH-CH-CO-) and PGE(1) itself. After intravenous injection in mice, the [111In]PGE(1) conjugate rapidly accumulated in the liver, whereas [111In]PLGA-HZ did not, suggesting the involvement of a galactose-specific mechanism in the uptake of the [111In]PGE(1) conjugate. Fractionation of liver cells revealed that the [111In]PGE(1) conjugate was preferentially taken up by liver parenchymal cells. The pharmacological activity was examined in mice with fulminant hepatitis induced by intraperitoneal injection of carbon tetrachloride. Intravenous injection of the PGE(1) conjugate at a dose of 1 mg (0.065 mg PGE(1))/kg effectively inhibited the increase in plasma glutamic pyruvic transaminase (GPT) activity compared with that of free PGE(1) at a dose of 0.065 or 0.65 mg/kg. These results suggest that the PGE(1) conjugate is an excellent prodrug for the treatment of fulminant hepatitis.

Enhanced gene transfection in macrophages using mannosylated cationic liposome-polyethylenimine-plasmid DNA complexes.

We have previously reported that plasmid DNA and cholesten-5-yloxy-N-(4-[(1-imino-2-beta-D-thiomannosylethyl)amino]butyl) formamide(Man-C4-Chol)/dioleoylphosphatidylethano-lamine(DOPE)(6:4) liposome complexes (DNA/Man-complexes) exhibit efficient gene transfection in macrophages via mannose receptor-mediated endocytosis. To further enhance gene transfetion, polyethylenimine (PEI) was incorporated into this liposome complex (DNA/Man-PEI-complexes), noticing a pH-buffering capacity in endosomes and DNA-condensing activity of PEI. In mouse peritoneal macrophages, the uptake and transfection activity of DNA/Man-PEI-complexes were 2-times and 6-times higher than those of DNA/Man-complexes, respectively. Furthermore, the presence of 1 mg/ml mannan significantly inhibited both the uptake and transfection efficiency of DNA/Man-PEI-complexes. These results suggested that the newly developed multifunctional DNA/Man-PEI-complexes exhibit highly improved gene transfection in macrophages via mannose receptor-mediated endocytosis.

Cell-specific delivery of genes with glycosylated carriers.

Cationic liposomes and polymers have been accepted as effective non-viral vectors for gene delivery with low immunogenicity unlike viral vectors. However, the lack of organ or cell specificity sometimes hampers their application and the development of a cell-specific targeting technology for them attracts great interest in gene therapy. In this review, the potential of cell-specific delivery of genes with glycosylated liposomes or polymers is discussed. Galactosylated liposomes and poly(amino acids) are selectively taken up by the asialoglycoprotein receptor-positive liver parenchymal cells in vitro and in vivo after intravenous injection. DNA-galactosylated cationic liposome complexes show higher DNA uptake and gene expression in the liver parenchymal cells in vitro than DNA complexes with bare cationic liposomes. In the in vitro gene transfer experiment, galactosylated liposome complexes are more efficient than DNA-galactosylated poly(amino acids) complexes but they have some difficulties in their biodistribution control. On the other hand, introduction of mannose residues to carriers resulted in specific delivery of genes to non-parenchymal liver cells. These results suggest advantages of these glycosylated carriers in cell-specific targeted delivery of genes.

Transport characteristics of ebastine and its metabolites across human intestinal epithelial Caco-2 cell monolayers.

The transport characteristics of a selective peripheral H1 receptor antagonist, ebastine, a substrate for cytochrome P450 3A4, and its three major metabolites, i.e., the hydroxy metabolite of ebastine (M-OH), the pharmacologically active metabolite carebastine (Car), and the desbutyrophenone metabolite (des-BP), were studied in cultured human intestinal Caco-2 cells expressing a drug efflux pump, P-glycoprotein (P-gp), on the apical membrane. The polarized transport of [3H]cyclosporin A (CyA), mediated by P-gp in the basolateral to apical direction across the Caco-2 cell monolayers, was affected by the presence of ebastine in a concentration-dependent manner and significant inhibition was observed at high concentrations (>50 microM). M-OH (300 microM) also significantly inhibited whereas Car and des-BP did not. Although no marked polarized transport of [14C]ebastine in a secretory direction was observed in the Caco-2 systems, the flux in the basolateral to apical direction was slightly higher than that in the opposite direction at concentrations less than 30 microm. [14C]Ebastine (2 microM) uptake from the apical side was significantly increased in the presence of an excess of cold CyA, suggesting that the efflux process mediated by P-gp may be involved in the ebastine uptake by Caco-2 cells. Collectively, these results indicate that ebastine (and presumably M-OH) is transported via P-gp in Caco-2 cells, however, the affinity for P-gp is very low. It is unlikely that the secretory transport of ebastine mediated by P-gp will dramatically affect overall intestinal absorption in vivo because efficient passive diffusion of this drug should occur due to its high lipophilicity. However, it may be advantageous for its efficient first-pass metabolism.