Search results for "Absorption"
showing 10 items of 2701 documents
IVIVC in oral absorption for fenofibrate immediate release tablets using a dissolution/permeation system.
2009
ABSTRACT: The usefulness of a dissolution/permeation (D/P) system to predict the in vivo performance of solid dosage forms containing the poorly soluble drug, fenofibrate, was studied. Biorelevant dissolution media simulating the fasted and fed state conditions of the human gastrointestinal tract were used in order to simulate the effect of food on the absorption of fenofibrate. Moreover, the results obtained from the D/P system were correlated with pharmacokinetic parameters obtained following in vivo studies in rats. The in vitro parameter (amount permeated in the D/P system) reflected well the in vivo performance in rats in terms of AUC and C max of fenofibric acid. This study thus demon…
Assessment and modulation of acamprosate intestinal absorption: comparative studies using in situ, in vitro (CACO-2 cell monolayers) and in vivo mode…
2003
The purpose of this study was to explore the intestinal absorption mechanism of acamprosate and to attempt to improve the bioavailability (BA) of the drug through modulation of its intestinal absorption using two enhancers (polysorbate 80 and sodium caprate) based on in situ, in vitro and in vivo models and comparing the results obtained. Intestinal transport of the drug, in the absence and in presence of polysorbate 80 (0.06, 0.28 and 9.6 mM) or sodium caprate (13 and 16 mM) was measured by using an in situ rat gut technique and Caco-2 cell monolayers. Additionally, the effect of sodium caprate on drug oral bioavailability, measured as urinary recovery, was quantified by performing in vivo…
Freeze-dried eudragit-hyaluronan multicompartment liposomes to improve the intestinal bioavailability of curcumin.
2016
This work aimed at finding an innovative vesicle-type formulation able to improve the bioavailability of curcumin upon oral administration. To this purpose, phospholipid, Eudragit® S100 and hyaluronan sodium salt were combined to obtain eudragit-hyaluronan immobilized vesicles using an easy and environmentally-friendly method. For the first time, the two polymers were combined in a system intended for oral delivery, to enhance curcumin stability when facing the harsh environment of the gastrointestinal tract. Four different formulations were prepared, keeping constant the amount of the phospholipid and varying the eudragit-hyaluronan ratio. The freeze-drying of the samples, performed to inc…
Impaired oral absorption of methylphenidate after Roux-en-Y gastric bypass
2017
The anatomic and physiologic changes in the gastrointestinal (GI) tract after bariatric surgery may significantly affect the pharmacokinetics of medications taken by the patients for various reasons. Unfortunately, there is little information regarding changes in drug absorption after bariatric surgeries, limiting the ability of medical professionals to produce clear recommendations on what changes should be made to the formulations and dosing regimens of drugs after bariatric surgery. In this article, we report and analyze a case of 52-year-old male patient with morbid obesity and attention-deficit/hyperactivity disorder (ADHD) who experienced lack of methylphenidate efficacy after Roux en…
Lymphatic Delivery and In Vitro Pancreatic Lipase Hydrolysis of Glycerol Esters of Conjugated Linoleic Acids in Rats
2000
We examined the intestinal delivery of conjugated linoleic acids (CLA) given in their triacylglycerol form in the mesenteric lymph of rats. Emulsions containing a mixture of the trilinolein/triester of CLA (9:1) and a tri-[1-(14)C]-linoleyl-sn-glycerol tracer were administered by force-feeding. Lymph was collected over two time periods (0-6 and 6-24 h), and the apparent recovery of CLA was determined relative to that of [1-(14)C]-18:2(n-6). A mixture of CLA-triester/trilinolein (1:9), trilinolein or CLA-triester was separately subjected to pancreatic lipase hydrolysis in vitro to determine whether the lymphatic recovery of CLA was correlated with the initial step of digestion. Lymphatic rec…
Pharmacokinetics, bioavailability and absorption of flumequine in the rat.
1999
Abstract The study demonstrates that the oral extent of bioavailability of flumequine in the rat, relative to the intravenous injection, is complete (0.94±0.04) and not significantly different from that found by the intraduodenal route (0.95±0.04). The rate of oral bioavailability, however, is slow ( k a =1.20±0.07 h −1 ; T max =2.0 h), but enough to maintain plasma levels above the minimal inhibitory concentration of the most common pathogens for an extended period of time (about 10 h). The reason for the oral absorption slowness could be a slow gastric emptying, an adsorption to the gastric mucosae, a precipitation in the gastric medium or any other feature concerning the stomach as the i…
Carbonic anhydrase activity in a calcium-mobilizing epithelium of the crustacean Orchestia cavimana during molting
1987
We investigated the involvement of the enzyme, carbonic anhydrase, in the calcification-decalcification processes occurring in the posterior caeca of the midgut of the terrestrial crustacean, Orchestia cavimana, before and after exuviation. This enzyme was ultrahistochemically localized throughout the membranes of the caecal epithelium as well as extracellularly, i.e., within pre-exuvial calcareous concretions and postexuvial calcified spherules. During the molt cycle, the pattern of carbonic anhydrase activity in the posterior caeca was correlated with the calcium content at this level. Acetazolamide treatment in vivo inhibited about 50% of the calcium uptake during both pre-exuvial secret…
Investigating drug absorption from the colon: Single-pass vs. Doluisio approaches to in-situ rat large-intestinal perfusion
2017
Traditionally, the colon is considered a secondary intestinal segment in the drug absorption process. However, in many cases the role of colonic drug permeability cannot be overlooked. The purpose of this research was to compare colon permeability data obtained using two different rat perfusion methods the single-pass intestinal perfusion (SPIP) approach and the closed-loop (Doluisio) perfusion model. A list of 14 structurally diverse model drugs was constructed, and their rat colon permeability was studied using the two methods. The two sets of results were compared to each other, and were evaluated vs. in-vitro, ex-vivo, and in-vivo literature values. The SPIP and the Doluisio results exh…
Biophysical Models as an Approach To Study Passive Absorption in Drug Development: 6-Fluoroquinolones
1995
A preliminary study attempting to assess and explain the intestinal absorption of a series of antibacterial 7-piperazinyl-6-fluoroquinolones is presented. The synthesis, n-octanol partition coefficients, intrinsic rat gut in situ absorption rate constants, and in vitro antibacterial activity data found for these homologous compounds are described. A fluorimetric, reverse-phase HPLC method was performed for the quantification of the quinolones in absorption and partition samples. Equations based on two classic biophysical absorption models are given for predicting the intrinsic absorption features of the series according to the partition data or merely single structural parameters. In situ a…
Segmental-dependent permeability throughout the small intestine following oral drug administration: Single-pass vs. Doluisio approach to in-situ rat …
2016
Abstract Intestinal drug permeability is position dependent and pertains to a specific point along the intestinal membrane, and the resulted segmental-dependent permeability phenomenon has been recognized as a critical factor in the overall absorption of drug following oral administration. The aim of this research was to compare segmental-dependent permeability data obtained from two different rat intestinal perfusion approaches: the single-pass intestinal perfusion (SPIP) model and the closed-loop (Doluisio) rat perfusion method. The rat intestinal permeability of 12 model drugs with different permeability characteristics (low, moderate, and high, as well as passively and actively absorbed…