Transintestinal transport mechanisms of 5-aminosalicylic acid (in situ rat intestine perfusion, Caco-2 cells) and Biopharmaceutics Classification System.

The aim of the study was 1) to estimate permeability of 5-aminosalicylic acid (5-ASA), 2) to categorize 5-ASA according to BCS (Biopharmaceutics Classification System), and 3) to contribute to determination of 5-ASA transintestinal transport and biotransformation mechanisms. The in situ rat intestine perfusion was used as an initial method to study 5-ASA transport. The amount of 5-ASA (released from tablet) transferred into portal circulation reached 5.79 ± 0.24%. During this transport, the intestinal formation of 5-ASA main metabolite (N-ac-5-ASA) occurred. N-ac-5-ASA was found in perfusate both from intestinal lumen and from v. portae. In in vitro Caco-2 monolayers, transport of 5-ASA (10-1000 µmol/l) was studied in apical-basolateral and basolateral-apical direction (iso-pH 7.4 conditions). The transport of total 5-ASA (parent drug plus intracellularly formed N-ac-5-ASA) was linear with time, concentration- and direction-dependent. Higher basolateral-apical (secretory) transport was mainly caused by higher transport of the metabolite (suggesting metabolite efflux transport). Transport of 5-ASA (only parent drug) was saturable (transepithelial carrier-mediated) at low doses, dominated by passive, paracellular process in higher doses which was confirmed by increased 5-ASA transport using Ca2+-free transport medium. The estimated low 5-ASA permeability and its low solubility enable to classify 5-ASA as BCS class IV.

The effect of probiotic Escherichia coli strain Nissle 1917 lipopolysaccharide on the 5-aminosalicylic acid transepithelial transport across Caco-2 cell monolayers.

The object of this study was to investigate the effect of probiotic Escherichia coli strain Nissle 1917 (EcN) (i) EcN lipopolysaccharide (EcN LPS) and (ii) bacteria-free supernatant of EcN suspension (EcN supernatant) on in vitro transepithelial transport of mesalazine (5-aminosalicylic acid, 5-ASA), the most commonly prescribed anti-inflammatory drug in inflammatory bowel disease (IBD). Effect of co-administered EcN LPS (100 µg/ml) or EcN supernatant (50 µg/ml) on the 5-ASA transport (300 µmol/l) was studied using the Caco-2 monolayer (a human colon carcinoma cell line) as a model of human intestinal absorption. Permeability characteristics for absorptive and secretory transport of parent drug and its intracellularly-formed metabolite were determined. The quantification of 5-ASA and its main metabolite N-acetyl-5-amino-salicylic acid (N-Ac-5-ASA) was performed by high performance liquid chromatography. Obtained results suggest that neither EcN LPS nor EcN supernatant had effect on the total 5-ASA transport (secretory flux greater than absorptive flux) and on the transport of intracellularly formed N-Ac-5-ASA (preferentially transported in the secretory direction). The percent cumulative transport of the total 5-ASA alone or in combination with EcN LPS or EcN supernatant did not exceed 1%.

Absorption kinetics of 5-aminosalicylic acid in rat: influence of indomethacin-induced gastrointestinal lesions and Escherichia Coli Nissle 1917 medication.

OBJECTIVES: The therapeutic effect of probiotics has been studied in many clinical and experimental studies but no data exist concerning the influence of probiotics on pharmacokinetics of contemporary administered drugs. In this paper, we describe the influence of indomethacin-induced gastrointestinal lesions and Escherichia Coli Nissle 1917 medication on absorption of 5-aminosalicylic acid and its metabolite N-acetyl-5-aminosalicylic acid in rat. METHODS: 5-aminosalicylic acid (5-ASA) was given orally to rat using gastric probe as a suspension (25 mg/kg). The plasma time profiles of 5-ASA and its metabolite were compared between Group A (animals medicated with a suspension of Escherichia coli Nissle 1917 [EcN] in dose of 5 × 108 CFUs/day for 14 consecutive days), Group B (animals with indomethacin [IND]-induced gastrointestinal lesions; single dose of 25 mg/kg of IND), Group C (simultaneous administration of EcN and IND), and Group D (control animals without any medication). The blood samples for HPLC analysis has been taken from incannulated vena jugularis in time 30, 60, 90, 120, 180, 240, 360 min after 5-ASA administration to rat. RESULTS: The pharmacokinetics of 5-ASA was not significantly changed by EcN medication (Group A) in comparison to control animals (Group D). The significantly elevated absorption (AUC and cmax) of 5-ASA was found in animals with induced gastro-enteropathy with concurrently medicated with EcN (Group C) when compred to controls. In the case of metabolite N-acetyl-5-ASA, statistically no-significant differences were found between groups. CONCLUSIONS: Simultaneous probiotics (EcN) medication did not affect absorption 5-ASA from intestinal tract (the main site of ASAs action).

Transepithelial transport of ambroxol hydrochloride across human intestinal Caco-2 cell monolayers.

This study aimed i) to characterize the transepithelial transport of the mucolytic agent ambroxol hydrochloride across the intestinal barrier, ii) to classify the ambroxol according to Biopharmaceutics Classification System (BCS) and iii) to predict ambroxol absorption in humans. Transport of ambroxol (100, 300 and 1000 micromol/l) was studied in a human colon carcinoma cell line Caco-2 in apical to basolateral and basolateral to apical direction, under iso-pH 7.4 and pH-gradient (6 vs. 7.4) conditions. The relative contribution of the paracellular route was estimated using Ca2+-free transport medium. Ambroxol samples from receiver compartments were analysed by HPLC with UV detection (242 nm). Results showed that ambroxol transport is linear with time, pH-dependent and direction-independent, displays non-saturable (first-order) kinetics. Thus, the transport seems to be transcellular mediated by passive diffusion. Estimated high solubility and high permeability (P(app) = 45 x 10(-6) cm/s) of ambroxol rank it among well absorbed compounds and class I of BCS. It can be expected that the oral dose fraction of ambroxol absorbed in human intestine is high.

Caco-2 cells and Biopharmaceutics Classification System (BCS) for prediction of transepithelial transport of xenobiotics (model drug: caffeine).

OBJECTIVES: The Caco-2 cell monolayer model is widely used as a standard screening tool for studying the mechanisms of cellular drug transport. Caffeine was chosen as a model drug and is supposed to be class I of the Biopharmaceutics Classification System (BCS). Our study was conducted 1) to characterize the mechanisms of caffeine transport across the intestinal barrier, 2) to classify caffeine according to BCS, 3) to predict drugs intestinal absorption in humans. METHODS: Caffeine transport (0.1, 0.3, 1 and 10 mmol/l) was studied in Caco-2 cell monolayer in apical to basolateral (AP-BL) and basolateral to apical (BL-AP) direction, under iso-pH 7.4 and pH-gradient (6/7.4) conditions. The relative contribution of the paracellular route was estimated using Ca2+- free transport medium (opening tight junctions). RESULTS: The caffeine transport was linear with time, transport direction and pH independent, displaying non-saturable (first-order) kinetics, with high permeability coefficient (Papp): in AP-BL direction Papp = 46.3-53.5 x 10-6 cm/s; in BL-AP direction Papp = 45.6-49.4 x 10-6 cm/s. Thus, the transport seems to be transcellular mediated by passive diffusion. Using Ca2+- free transport medium tight junctions were opened (confirmed by increased Papp of mannitol) but the caffeine Papp was not changed. Thus, the paracellular route is only a minor way of caffeine transport. CONCLUSION: High solubility and high permeability of caffeine rank it among class I of BCS and well absorbed compounds.