In vitro model for predicting the access and distribution of drugs in the brain using hCMEC/D3 cells.

The BBB is a protective entity that prevents external substances from reaching the CNS but it also hinders the delivery of drugs into the brain when they are needed. The main objective of this work was to improve a previously proposed in vitro cell-based model by using a more physiological cell line (hCMEC/D3) to predict the main pharmacokinetic parameters that describe the access and distribution of drugs in the CNS: Kpuu,brain, fu,plasma, fu,brain and Vu,brain. The hCMEC/D3 permeability of seven drugs was studied in transwell systems under different conditions (standard, modified with albumin and modified with brain homogenate). From the permeability coefficients of those experiments, the parameters mentioned above were calculated and four linear IVIVCs were established. The best ones were those that relate the in vitro and in vivo Vu,brain and fu,brain (r2 = 0.961 and r2 = 0.940) which represent the binding rate of a substance to the brain tissue, evidencing the importance of using brain homogenate to mimic brain tissue when an in vitro brain permeability assay is done. This methodology could be a high-throughput screening tool in drug development to select the CNS promising drugs in three different in vitro BBB models (hCMEC/D3, MDCK and MDCK-MDR1).

Eremantholide C from aerial parts of Lychnophora trichocarpha, as drug candidate: fraction absorbed prediction in humans and BCS permeability class determination.

BACKGROUND: Lychnophora trichocarpha (Spreng.) Spreng. ex Sch.Bip has been used in folk medicine to treat pain, inflammation, rheumatism and bruises. Eremantholide C, a sesquiterpene lactone, is one of the substances responsible for the anti-inflammatory and anti-hyperuricemic effects of L. trichocarpha. OBJECTIVES: Considering the potential to become a drug for the treatment of inflammation and gouty arthritis, this study evaluated the permeability of eremantholide C using in situ intestinal perfusion in rats. From the permeability data, it was possible to predict the fraction absorbed of eremantholide C in humans and elucidate its oral absorption process. METHODS: In situ intestinal perfusion studies were performed in the complete small intestine of rats using different concentrations of eremantholide C: 960 µg/ml, 96 µg/ml and 9.6 µg/ml (with and without sodium azide), in order to verify the lack of dependence on the measured permeability as a function of the substance concentration in the perfusion solutions. RESULTS: Eremantholide C showed Peff values, in rats, greater than 5 × 10-5 cm/s and fraction absorbed predicted for humans greater than 85%. These results indicated the high permeability for eremantholide C. Moreover, its permeation process occurs only by passive route, because there were no statistically significant differences between the Peff values for eremantholide C. CONCLUSION: The high permeability, in addition to the low solubility, indicated that eremantholide C is a biologically active substance BCS class II. The pharmacological activities, low toxicity and biopharmaceutics parameters demonstrate that eremantholide C has the necessary requirements for the development of a drug product, to be administered orally, with action on inflammation, hyperuricemia and gout.

Intestinal Permeability Study of Clinically Relevant Formulations of Silibinin in Caco-2 Cell Monolayers.

An ever-growing number of preclinical studies have investigated the tumoricidal activity of the milk thistle flavonolignan silibinin. The clinical value of silibinin as a bona fide anti-cancer therapy, however, remains uncertain with respect to its bioavailability and blood⁻brain barrier (BBB) permeability. To shed some light on the absorption and bioavailability of silibinin, we utilized the Caco-2 cell monolayer model of human intestinal absorption to evaluate the permeation properties of three different formulations of silibinin: silibinin-meglumine, a water-soluble form of silibinin complexed with the amino-sugar meglumine; silibinin-phosphatidylcholine, the phytolipid delivery system Siliphos; and Eurosil85/Euromed, a milk thistle extract that is the active component of the nutraceutical Legasil with enhanced bioavailability. Our approach predicted differential mechanisms of transport and blood⁻brain barrier permeabilities between the silibinin formulations tested. Our assessment might provide valuable information about an idoneous silibinin formulation capable of reaching target cancer tissues and accounting for the observed clinical effects of silibinin, including a recently reported meaningful central nervous system activity against brain metastases.

Preclinical models for colonic absorption, application to controlled release formulation development.

Oral controlled release (CR) formulations have many benefits and have become a valuable resource for the local and systemic administration of drugs. The most important characteristic of these pharmaceutical products is that drug absorption occurs mainly in the colon. Therefore, this review analyses the physiological and physicochemical features that may affect an orally administered CR product, as well as the different strategies to develop a CR dosage form and the methods used to evaluate the formulation efficacy. The models available to study the intestinal permeability and their applicability to colonic permeability determinations are also discussed.

Evaluation of the intestinal permeability of rosemary (Rosmarinus officinalis L.) extract polyphenols and terpenoids in Caco-2 cell monolayers.

Rosemary (Rosmarinus officinalis) is grown throughout the world and is widely used as a medicinal herb and to season and preserve food. Rosemary polyphenols and terpenoids have attracted great interest due to their potential health benefits. However, complete information regarding their absorption and bioavailability in Caco-2 cell model is scarce. The permeation properties of the bioactive compounds (flavonoids, diterpenes, triterpenes and phenylpropanoids) of a rosemary extract (RE), obtained by supercritical fluid extraction, was studied in Caco-2 cell monolayer model, both in a free form or liposomed. Compounds were identified and quantitated by liquid chromatography coupled to quadrupole time-of-flight with electrospray ionization mass spectrometry analysis (HPLC-ESI-QTOF-MS), and the apparent permeability values (Papp) were determined, for the first time in the extract, for 24 compounds in both directions across cell monolayer. For some compounds, such as triterpenoids and some flavonoids, Papp values found were reported for the first time in Caco-2 cells.Our results indicate that most compounds are scarcely absorbed, and passive diffusion is suggested to be the primary mechanism of absorption. The use of liposomes to vehiculize the extract resulted in reduced permeability for most compounds. Finally, the biopharmaceutical classification (BCS) of all the compounds was achieved according to their permeability and solubility data for bioequivalence purposes. BCS study reveal that most of the RE compounds could be classified as classes III and IV (low permeability); therefore, RE itself should also be classified into this category.

Permeability Study of Polyphenols Derived from a Phenolic-Enriched Hibiscus sabdariffa Extract by UHPLC-ESI-UHR-Qq-TOF-MS.

Previous findings on the capacity of Hibiscus sabdariffa (HS) polyphenols to ameliorate metabolic disturbances justify the necessity of studies oriented to find the potential metabolites responsible for such an effect. The present study examined the intestinal epithelial membrane permeability of polyphenols present in a phenolic-enriched Hibiscus sabdariffa extract (PEHS), free and encapsulated, using the Caco-2 cell line. Additionally, selected polyphenols (quercetin, quercetin-3-glucoside, quercetin-3-glucuronide, and N-feruloyltyramine) were also studied in the same absorption model. The powerful analytical platform used ultra-high-performance liquid chromatography coupled with ultra-high-resolution quadrupole time-of-flight mass spectrometry (UHPLC-ESI-UHR-Qq-TOF-MS), and enabled the characterization of seven new compounds in PEHS. In the permeation study, only a few compounds were able to cross the cell monolayer and the permeability was lower when the extract was in an encapsulated form. Pure compounds showed a moderate absorption in all cases. Nevertheless, these preliminary results may need further research to understand the complete absorption mechanism of Hibiscus polyphenols.

A new mathematical approach for the estimation of the AUC and its variability under different experimental designs in preclinical studies.

The aim of the present work was to develop a new mathematical method for estimating the area under the curve (AUC) and its variability that could be applied in different preclinical experimental designs and amenable to be implemented in standard calculation worksheets. In order to assess the usefulness of the new approach, different experimental scenarios were studied and the results were compared with those obtained with commonly used software: WinNonlin® and Phoenix WinNonlin®. The results do not show statistical differences among the AUC values obtained by both procedures, but the new method appears to be a better estimator of the AUC standard error, measured as the coverage of 95% confidence interval. In this way, the new proposed method demonstrates to be as useful as WinNonlin® software when it was applicable.