HepG2 cell monolayers, formed during cell growth on collagen-coated Transwell (Corningr Inc., Corning, NY, USA) inserts, can be used for the evaluation of interactions between food supplements and drugs that are substrates for P-glycoprotein (Pgp) and/or multidrug resistance-associated protein 2 (MRP-2). Samples obtained during such permeability studies were relatively free of intracellular proteins or cell debris compared to usually performed uptake experiments with HepG2 cells; therefore no special preparation protocol prior to the analysis was needed. In the presence of aged garlic extract the activities of hepatic efflux transporters (Pgp, MRP-2) changed, which was observed as significant permeability changes of tested human immunodeficiency virus (HIV) protease inhibitors. Darunavir efflux significantly increased, whereas that of saquinavir significantly decreased. Because of the observed in vitro interactions between aged garlic extract and HIV protease inhibitors (darunavir, saquinavir), any alterations of in vivo liver transport in the presence of garlic phytochemicals could also significantly influence darunavir/saquinavir hepatocyte intracellular concentrations and hence their bioavailabilities. Therefore this aspect needs further in vivo animal evaluation.
COBISS.SI-ID: 2929521
The application of CACO-2 cell models as a supportive in vitro tool during drug discovery and formulation development aims to address the oral absorption of drug candidates with different degrees of predictive efficiency, depending on the inherent CACO-2 cell characteristics and on the intra-laboratory quality control protocols. Although CACO-2 cell permeability studies probe a certain subset of experimental questions, careful interpretation of the obtained data should be exercised on more complex issues, which include the interplay between multiple biological functions. In the first part of the presented paper the academic applicability of CACO-2 cells for investigating drug-food interactions arising as a consequence of modified transporter activities is demonstrated. To illustrate these claims, the suitability of the CACO-2 cell monolayers as a reliable instrument in predicting the absorption is manifested first. Then the impact of garlic supplement (aged garlic extract) on the permeability of selected cardiovascular, antidiabetic and antiviral drugs is presented and compared to the permeability determined through the isolated segments of a rat small intestine. Based on the provided review regarding the (dis)similarities in the transporter and enzyme expression between this cancerous cell line and intestinal tissue, the observed qualitative pharmacokinetic transporter-drug interactions are considered in the context of their in vivo relevance. The second part of the paper focuses on the industrial interest in CACO-2 models as means to evaluate novel drug delivery systems. Development of adequate pharmaceutical formulation is the valuable key step for improving poor water solubility and/or poor membrane permeability that are responsible for the low fraction of the drug dose absorbed. Modern approaches to address this problem include administration of drug with lipid-based systems. Model drug furosemide, classified as a low permeable and a low soluble drug (bcs CLASS 4), was used to identify beneficial properties of these novel drug delivery systems, that could help to overcome the absorption hindrances and could offer new possibilities for oral administration of other compounds with unfavorable physico-chemical properties.
COBISS.SI-ID: 3130737
The suboptimal penetration of highly active antiretroviral therapy (HAART) drugs into the virus reservoirs and sanctuary sites ensures that the replication-competent HIV viruses or integrated HIV virions remain protected, which leads to the disease relapse and to the emergence of virus resistance. The persistent opportunistic infections alongside the metabolic syndrome thus contribute to the concomitant consumption of garlic supplements to ameliorate these symptoms. However garlic phytochemicals have been shown to modulate the activities of intestinal and hepatic transporters and CYP3A4 enzymes. Concomitant application of antiretrovirals and garlic supplements could thus lead to pharmacokinetic interactions and possibly to therapy failure or to intensification of undesired effects. To address the questions regarding the safety of long-term garlic supplementation on HAART drugs - saquinavir (Saq)and darunavir (Dar), two types of garlic supplements (water-based Aged Garlic Extract - AGE and and oil-based Garlic Oli Macerate - GOM) were evaluated with hepatic and intestinal tissues of rats, fed these two garlic supplements for two weeks. Based on the knowledge of short-term influence of garlic phytochemicals and/or supplements on transporter-enzyme interplay (Berginc et al, 2009; Berginc et al, 2010a) and clinical data for Saq (Piscitelli et al, 2002), the mechanisms behind pharmacokinetic interactions between Saq/Dar and garlic were elucidated. Both drugs displayed very low permeability and were subjected to a profound efflux from enterocyte, because the components of garlic supplements and/or their metabolites readily bind to efflux transporters and change the activities of efflux transporters by allosteric modifications in short-term and increase their expression in the long run. ABC transporter activity in the intestine increased regardless of which garlic supplement was used. Long-term garlic supplementation also affected hepatic metabolism and distribution by up-regulating expression of uptake Oatps transporters (the effect on efflux transporters was minor), which resulted in the overall increased intrahepatic HIV-PI amounts that could be further subjected to Cyp3A metabolism. Cyp3A Dar (not Saq) metabolism was significantly inhibited by AGE, while in GOM treated rats the Cyp3A metabolism of both drugs significantly increased, highlighting important dissimilarities in plasma profiles of garlic phytochemicals and the corresponding metabolites, as shown in this study. Regarding the fact that garlic supplements are so widely used in the HIV infected population because of their protective cardiovascular and anti-infective effects, further research should be directed to the identification of high- and low-risk supplement – drug combinations.
COBISS.SI-ID: 3188337