Biopharmaceutical Classification System in Invitro/ In-vivo Correlation: Concept and Development Strategies in Drug Delivery

Drug development is a very laborious and expensive process. One of the major reasons for failure during the clinical phases of drug development is inadequate pharmacokinetic data on the drug candidate. Therefore, it would be advantageous if the pharmacokinetic properties of drug candidates be predicted beforehand. One major obstacle in making such  predictions is the inability to appropriately scale the in-vitro data to the in-vivo situation. Results from in-vitro in-vivo correlation (IVIVC) studies have been used to select the appropriate excipients and optimize the manufacturing processes for quality control purposes, and for characterizing the release patterns of newly formulated immediate release, and modified-release products relative to the references. In recent years, the concept and application of the IVIVC for pharmaceutical dosage forms have been a major focus of attention in the pharmaceutical industry, academia and regulatory agencies. Hence, this article highlights the importance of appropriate selection of IVIVC level with respect to the Biopharmaceutical Classification System (BCS) and also covers examples of BCS-based IVIVCs of drugs/products with different types of release profiles.Keywords: In vitro/In vivo correlation, Biopharmaceutical Classification System, Drug Delivery

Biopharmaceutical classification system In invitro/ In-vivo correlation: Concept and development strategies in drug delivery

Drug development is a very laborious and expensive process. One of the major reasons for failure during the clinical phases of drug development is inadequate pharmacokinetic data on the drug candidate. Therefore, it would be advantageous if the pharmacokinetic properties of drug candidates be predicted beforehand. One major obstacle in making such predictions is the inability to appropriately scale the in-vitro data to the in-vivo situation. Results from in-vitro in-vivo correlation (IVIVC) studies have been used to select the appropriate excipients and optimize the manufacturing processes for quality control purposes, and for characterizing the release patterns of newly formulated immediate release, and modified-release products relative to the references. In recent years, the concept and application of the IVIVC for pharmaceutical dosage forms have been a major focus of attention in the pharmaceutical industry, academia and regulatory agencies. Hence, this article highlights the importance of appropriate selection of IVIVC level with respect to the Biopharmaceutical Classification System (BCS) and also covers examples of BCS-based IVIVCs of drugs/products with different types of release profiles

MR imaging features of benign retroperitoneal extra-adrenal paragangliomas

The goal of this study was to retrospectively review the magnetic resonance imaging (MRI) features of retroperitoneal extra-adrenal paragangliomas and to evaluate the diagnostic capabilities of MRI. Twenty-four patients with confirmed benign retroperitoneal extra-adrenal paragangliomas who underwent preoperative MRI and surgical resection were enrolled. The patients’ clinical characteristics and MRI features were reviewed by two radiologists. There were no significant differences in the qualitative and quantitative MRI features were determined by the reviewers. High signal intensity in T2- weighted imaging (T2WI) and diffusion-weighted imaging (DWI) was observed in all tumors. In contrast T1-weighted imaging (T1WI) in the arterial phase, 83.33% of the tumors were clearly enhanced. In 87.5% of cases, a persistent enhancement pattern was observed in the venous and delayed phases, and 12.5% of tumors showed a “washout” pattern. The tumor capsule, intratumoral septum and degenerations were visualized in the tumors and may be helpful in the qualitative diagnosis of extraadrenal paragangliomas in MRI. MRI was useful in locating the position, determining the tumor ranges and visualizing the relationship between the tumors and adjacent structures. The presence of typical clinical symptoms and positivity of biochemical tests are also important factors in making an accurate preoperative diagnosis