verlukast and tryptoquivaline

Sulfasalazine is characterized by low intestinal absorption, which essentially enables its colonic targeting and therapeutic action. The mechanisms behind this low absorption have not yet been elucidated. The purpose of this study was to investigate the role of efflux transporters in the intestinal absorption of sulfasalazine as a potential mechanism for its low small-intestinal absorption and colonic targeting following oral administration. The effects of P-glycoprotein (P-gp), multidrug resistance-associated protein 2 (MRP2), and breast cancer resistance protein (BCRP) inhibitors on sulfasalazine bidirectional permeability were studied across Caco-2 cell monolayers, including dose-response analysis. Sulfasalazine in vivo permeability was then investigated in the rat jejunum by single-pass perfusion, in the presence vs. absence of inhibitors. Sulfasalazine exhibited 19-fold higher basolateral-to-apical (BL-AP) than apical-to-basolateral (AP-BL) Caco-2 permeability, indicative of net mucosal secretion. MRP2 inhibitors (MK-571 and indomethacin) and BCRP inhibitors [fumitremorgin C (FTC) and pantoprazole] significantly increased AP-BL and decreased BL-AP sulfasalazine Caco-2 transport in a concentration-dependent manner. No effect was observed with the P-gp inhibitors verapamil and quinidine. The IC50 values of the specific MRP2 and BCRP inhibitors MK-571 and FTC on sulfasalazine secretion were 21.5 and 2.0 microM, respectively. Simultaneous inhibition of MRP2 and BCRP completely abolished sulfasalazine Caco-2 efflux. Without inhibitors, sulfasalazine displayed low (vs. metoprolol) in vivo intestinal permeability in the rat model. MK-571 or FTC significantly increased sulfasalazine permeability, bringing it to the low-high permeability boundary. With both MK-571 and FTC present, sulfasalazine displayed high permeability. In conclusion, efflux transport mediated by MRP2 and BCRP, but not P-gp, shifts sulfasalazine permeability from high to low, thereby enabling its colonic targeting and therapeutic action. To our knowledge, this is the first demonstration of intestinal efflux acting in favor of oral drug delivery.

Topics: 2-Pyridinylmethylsulfinylbenzimidazoles; Administration, Oral; Animals; ATP Binding Cassette Transporter, Subfamily B, Member 1; ATP Binding Cassette Transporter, Subfamily G, Member 2; ATP-Binding Cassette Transporters; Biological Transport; Caco-2 Cells; Colon; Dose-Response Relationship, Drug; Drug Delivery Systems; Humans; Indoles; Indomethacin; Intestinal Absorption; Intestine, Small; Kinetics; Male; Multidrug Resistance-Associated Protein 2; Multidrug Resistance-Associated Proteins; Neoplasm Proteins; Pantoprazole; Perfusion; Permeability; Propionates; Quinolines; Rats; Rats, Wistar; Sulfasalazine

The objective of the present study was to investigate the reliability of transporter inhibitors in the elucidation of drug-transporter interactions when multiple transporters are present in a test system. The bidirectional permeabilities of digoxin, estrone-3-sulfate (E3S), and sulfasalazine, substrates of P-gp, BCRP/MRP2 and unspecified efflux transporters, respectively, were examined in Caco-2 and MDR-MDCK cells in the absence and presence of transporter inhibitors: CsA (P-gp), FTC (BCRP) and MK571 (MRP). Digoxin showed significant efflux ratios (ER) in both Caco-2 (ER=17) and MDR-MDCK (ER=120), whereas E3S and sulfasalazine only showed significant efflux in Caco-2 (ER=15 and 88, respectively) but not in MDR-MDCK cells (ER=1.1 and 1.3, respectively). CsA at 10 microM showed complete inhibition of digoxin efflux, partial inhibition of E3S efflux and no effect on sulfasalazine efflux. FTC and MK571 had different inhibitory effects on the efflux of these compounds. The present study shows evidence of the functional expression of multiple efflux transporter systems in Caco-2 cells. Although the use of Caco-2 cells and selected inhibitors of efflux transporters can provide useful mechanistic information on drug-drug interactions involving efflux transporters, the potential cross-reaction of inhibitors with multiple transporters makes it difficult to discern the role of individual transporters in drug transport or drug-drug interactions.

Topics: Animals; ATP Binding Cassette Transporter, Subfamily B, Member 1; ATP Binding Cassette Transporter, Subfamily G, Member 2; ATP-Binding Cassette Transporters; Biological Transport; Caco-2 Cells; Cell Line; Cyclosporine; Digoxin; Dogs; Drug Interactions; Estrone; Humans; Indoles; Kidney; Multidrug Resistance-Associated Proteins; Neoplasm Proteins; Permeability; Propionates; Quinolines; Sulfasalazine

Overexpression of the transporter ABCG2, also known as breast cancer resistance protein and mitoxantrone resistance protein, can confer resistance to a variety of cytostatic drugs, such as mitoxantrone, topotecan, doxorubicin, and daunorubicin. This study analyzes the ABCG2 expression and activity in 46 human de novo acute lymphoblastic leukemia B- and T-lineage (ALL) samples.. ABCG2 expression was measured flow cytometrically with the BXP-34 monoclonal antibody. ABCG2 functional activity was determined flow cytometrically by measuring mitoxantrone accumulation in combination with the ABCG2 inhibitor fumitremorgin C (FTC). To determine a possible effect of the transporters P-glycoprotein and multidrug resistance-associated protein (MRP1 and MRP2) on mitoxantrone accumulation, the accumulation was investigated in the presence of the P-glycoprotein inhibitor PSC 833 and MRP inhibitor MK-571. The ABCG2 gene was sequenced to investigate the amino acid at position 482.. In B-lineage ALL (n = 23), the median BXP-34:IgG1 ratio was higher, namely 2.4 (range, 1.7-3.7), than in T-lineage ALL (n = 23; 1.9; range, 1.2-6.6; P = 0.003). The addition of FTC to mitoxantrone treatment caused a median increase in mitoxantrone accumulation of 21% (range, 0-140%) in B-lineage ALL. In T-lineage ALL, this FTC effect was less pronounced (5%; range, 0-256%; P = 0.013). The influence of FTC on mitoxantrone accumulation correlated with ABCG2 protein expression (r = 0.52; P < 0.001; n = 43). The increase in mitoxantrone accumulation, when FTC was added to cells treated with both PSC 833 and MK-571, correlated with the ABCG2 expression in B-lineage ALL but not in T-lineage ALL. Sequencing the ABCG2 gene revealed no ABCG2 mutation at position 482 in patients who accumulated more rhodamine after FTC.. This study shows that ABCG2 is expressed higher and functionally more active in B-lineage than in T-lineage ALL.

Topics: Adolescent; Adult; Aged; Antibodies, Monoclonal; Antineoplastic Agents; ATP Binding Cassette Transporter, Subfamily B, Member 1; ATP Binding Cassette Transporter, Subfamily G, Member 2; ATP-Binding Cassette Transporters; Bronchodilator Agents; Burkitt Lymphoma; Child; Child, Preschool; Cyclosporins; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Female; Flow Cytometry; Gene Expression Regulation, Leukemic; Gene Expression Regulation, Neoplastic; Humans; Indoles; Infant; Leukemia-Lymphoma, Adult T-Cell; Male; Middle Aged; Mitoxantrone; Multidrug Resistance-Associated Proteins; Neoplasm Proteins; Propionates; Quinolines; Tumor Cells, Cultured