Auflistung nach Autor:in "Reppas, Christos"

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In vitro methods to assess drug precipitation in the fasted small intestine – a PEARRL review
(Wiley, 06/2018) O'Dwyer, Patrick J.; Litou, Chara; Box, Karl, J.; Dressman, Jennifer; Kostewicz, Edmund, S.; Kuentz, Martin; Reppas, Christos
Objectives Drug precipitation in vivo poses a significant challenge for the pharmaceutical industry. During the drug development process, the impact of drug supersaturation or precipitation on the in vivo behaviour of drug products is evaluated with in vitro techniques. This review focuses on the small and full scale in vitro methods to assess drug precipitation in the fasted small intestine. Key findings Many methods have been developed in an attempt to evaluate drug precipitation in the fasted state, with varying degrees of complexity and scale. In early stages of drug development, when drug quantities are typically limited, small‐scale tests facilitate an early evaluation of the potential precipitation risk in vivo and allow rapid screening of prototype formulations. At later stages of formulation development, full‐scale methods are necessary to predict the behaviour of formulations at clinically relevant doses. Multicompartment models allow the evaluation of drug precipitation after transfer from stomach to the upper small intestine. Optimisation of available biopharmaceutics tools for evaluating precipitation in the fasted small intestine is crucial for accelerating the development of novel breakthrough medicines and reducing the development costs. Summary Despite the progress from compendial quality control dissolution methods, further work is required to validate the usefulness of proposed setups and to increase their biorelevance, particularly in simulating the absorption of drug along the intestinal lumen. Coupling results from in vitro testing with physiologically based pharmacokinetic modelling holds significant promise and requires further evaluation.
01A - Beitrag in wissenschaftlicher Zeitschrift
Leveraging the use of in vitro and computational methods to support the development of enabling oral drug products. An InPharma commentary
(Elsevier, 01.09.2023) Reppas, Christos; Kuentz, Martin; Bauer-Brandl, Annette; Carlert, Sara; Dallmann, André; Dietrich, Shirin; Dressman, Jennifer; Ejskjaer, Lotte; Frechen, Sebastian; Guidetti, Matteo; Holm, René; Holzem, Florentin Lukas; Karlsson, Εva; Kostewicz, Edmund; Panbachi, Shaida; Paulus, Felix; Senniksen, Malte Bøgh; Stillhart, Cordula; Turner, David B.; Vertzoni, Maria; Vrenken, Paul; Zöller, Laurin; Griffin, Brendan T.; O'Dwyer, Patrick J.
01A - Beitrag in wissenschaftlicher Zeitschrift
On the usefulness of four in vitro methods in assessing the intraluminal performance of poorly soluble, ionisable compounds in the fasted state
(Elsevier, 2022) O'Dwyer, Patrick J.; Box, Karl J.; Imanidis, Georgios; Vertzoni, Maria; Reppas, Christos
A small-scale two-stage biphasic system, a small-scale two-stage dissolution-permeation system, the Erweka mini-paddle apparatus, and the BioGIT system were evaluated for their usefulness in assessing the intraluminal performance of two low solubility drugs in the fasted state, one with weakly acidic properties (tested in a salt form, diclofenac potassium) and one with weakly alkaline properties [ritonavir, tested as an amorphous solid dispersion (ASD) formulation]. In all in vitro methods, an immediate-release tablet and a powder formulation of diclofenac potassium were both rapidly dissolved in Level II biorelevant media simulating the conditions in the upper small intestine. Physiologically based biopharmaceutics (PBB) modelling for the tablet formulation resulted in a successful simulation of the average plasma profile in adults, whereas for the powder formulation modelling indicated that gastric emptying and transport through the intestinal epithelium limit the absorption rates. Detailed information on the behaviour of the ritonavir ASD formulation under both simulated gastric and upper small intestinal conditions were crucial for understanding the luminal performance. PBB modelling showed that the dissolution and precipitation parameters, estimated from the Erweka mini-paddle apparatus data and the small-scale two-stage biphasic system data, respectively, were necessary to adequately simulate the average plasma profile after administration of the ritonavir ASD formulation. Simulation of the gastrointestinal transfer process from the stomach to the small intestine was necessary to evaluate the effects of hypochlorhydric conditions on the luminal performance of the ritonavir ASD formulation.
01A - Beitrag in wissenschaftlicher Zeitschrift