One-Step Preparation of Poly-Lactic-Co-Glycolic-Acid Microparticles to Prevent the Initial Burst Release of Encapsulated Water-Soluble Proteins

An initial burst is often observed during the release of active pharmaceutical ingredients (APIs) from poly-lactic-coglycolic-acid (PLGA) microparticles (MPs) which have been prepared by the emulsion-solvent evaporation method. Herein, we describe the development of a simple one-step coating method that suppresses the initial burst release process. This new method involves coating the PLGA-MPs with PLGA, with the coating process being performed through the phase separation of PLGA on the surface of PLGA-MPs using the emulsion-solvent evaporation method. Bovine serum albumin (BSA) was encapsulated in the PLGA-MPs as a model API. The coated MPs were spherical in shape with no pores on their smooth surface, whereas the non-coated PLGA-MPs had porous surfaces. An in vitro release study showed that the residual levels of BSA in the coated and non-coated PLGA-MPs after 1 h were about 99% and 16% of the original loads, respectively. The one-step coating method therefore represents a useful method for preparing PLGA-MPs that do not give an initial burst release of proteinaceous APIs.

Control strategy and methods for continuous direct compression processes

We presented a control strategy for tablet manufacturing processes based on continuous direct compression.The work was conducted by the experts of pharmaceutical companies,machine suppliers,academia,and regulatory authority in Japan.Among different items in the process,the component ratio and blended powder content were selected as the items requiring the control method specific to continuous manufacturing different from the conventional batch manufacturing.The control and management of the Loss in Weight(LIW)feeder were deemed the most important,and the Residence Time Distribution(RTD)model were regarded effective for setting the control range and for controlling of the LIW feeder.Based on these ideas,the concept of process control using RTD was summarized.

Pharmacokinetic aspects and in vitro–in vivo correlation potential for lipid-based formulations

Lipid-based formulations have been an attractive choice among novel drug delivery systems for enhancing the solubility and bioavailability of poorly soluble drugs due to their ability to keep the drug in solubilized state in the gastrointestinal tract.These formulations offer multiple advantages such as reduction in food effect and inter-individual variability,ease of preparation,and the possibility of manufacturing using common excipients available in the market.Despite these advantages,very few products are available in the present market,perhaps due to limited knowledge in the in vitro tests(for prediction of in vivo fate)and lack of understanding of the mechanisms behind pharmacokinetic and biopharmaceutical aspects of lipid formulations after oral administration.The current review aims to provide a detailed understanding of the in vivo processing steps involved after oral administration of lipid formulations,their pharmacokinetic aspects and in vitro in vivo correlation(IVIVC)perspectives.Various pharmacokinetic and biopharmaceutical aspects such as formulation dispersion and lipid digestion,bioavailability enhancement mechanisms,impact of excipients on efflux transporters,and lymphatic transport are discussed with examples.In addition,various IVIVC approaches towards predicting in vivo data from in vitro dispersion/precipitation,in vitro lipolysis and ex vivo permeation studies are also discussed in detail with help of case studies.

Research advances in peptide-drug conjugates

Peptide-drug conjugates(PDCs)are drug delivery systems consisting of a drug covalently coupled to a multifunctional peptide via a cleavable linker.As an emerging prodrug strategy,PDCs not only preserve the function and bioactivity of the peptides but also release the drugs responsively with the cleavable property of the linkers.Given the ability to significantly improve the circulation stability and targeting of drugs in vivo and reduce the toxic side effects of drugs,PDCs have already been extensively applied in drug delivery.Herein,we review the types and mechanisms of peptides,linkers and drugs used to construct PDCs,and summarize the clinical applications and challenges of PDC drugs.

Versatile flexible micelles integrating mucosal penetration and intestinal targeting for effectively oral delivery of paclitaxel

The extremely low bioavailability of oral paclitaxel(PTX)mainly due to the complicated gastrointestinal environment,the obstruction of intestinal mucus layer and epithelium barrier.Thus,it is of great significance to construct a coordinative delivery system which can overcome multiple intestinal physicochemical obstacles simultaneously.In this work,a high-density PEGylation-based glycocholic acid-decorated micelles(PTX@GNPs)was constructed by a novel polymer,9-Fluorenylmethoxy carbonyl-poly ethylene glycocholic acid(Fmoc-PEG-GCA).The Fmoc motif in this polymer could encapsulate PTX viaπ-πstacking to form the core of micelles,and the low molecular weight and non-long hydrophobic chain of Fmoc ensures the high-density of PEG.Based on this versatile and flexible carriers,PTX@GNPs possess mucus trapping escape ability due to the flexible PEG,and excellent intestine epithelium targeting attributed to the high affinity of GCA with apical sodium-dependent bile acid transporter.The in vitro and in vivo results showed that this oral micelle could enhance oral bioavailability of PTX,and exhibited similar antitumor efficacy to Taxol injection via intravenous route.In addition,oral PTX@GNPs administered with lower dosage within shorter interval could increase in vivo retention time of PTX,which supposed to remodel immune microenvironment and enhance oral chemotherapy efficacy by synergistic effect.