Liposomes
Danilo D. Lasic in LIPOSOMES in GENE DELIVERY, 2019
Liposomes are vesicular colloidal particles composed of self-assembled amphiphilic molecules. Amphiphiles are molecules that contain two groups with different solubility. The hydrophilic group, often referred to as the polar head, is “water loving,” while the hydrophobic part, the so-called nonpolar tail, is “water hating.” The structure of lipid systems can be approximated by taking into account the geometric properties of these amphiphiles. In the case when the polar part is larger than the nonpolar tail, the molecules tend to pack into structures with high radii of curvature. Positively charged lipids, with the exceptions of sphingosine and some lipids in primitive life forms, practically do not exist in nature. Before the explosion in lipid synthesis in the early 1990s several cationic detergents were used for preparation of liposomes with positive charge. There are several very important parameters describing properties of detergents and lipids.
The Challenge Of Liposome Targeting In Vivo
Gregory Gregoriadis in Liposome Technology, 2018
This chapter provides a brief survey of the factors which can influence the behavior and fate of liposomes in vivo when administered by a variety of routes and their implications for liposome targeting. Interest in liposomes has continued to grow as evidenced by the substantial increase in the number of publications and meetings devoted to the subject and by the formation of new companies for commercial development of liposomes as drug delivery systems, vaccines, and diagnostic tools. Targeting of liposomes to a specific cell type in vivo requires successful completion of several independent steps: access to the appropriate target cell, recognition and selective interaction with the target cell with little or no uptake by non target cells. Some of the proposed uses of liposomes as a drug-delivery system, notably drug delivery to the mononuclear phagocyte system, already achieved practical reality.
Liposomes as novel drug delivery vehicle
Suryakant Swain, Chinam Niranjan Patra, M. E. Bhanoji Rao in Pharmaceutical drug delivery systems and vehicles, 2018
This chapter focuses on different types of liposome-based technology and depot polymeric scaffold technologies, various methods for embedding drug-loaded liposomes within a depot, and various approaches reported to control the rate of sustained drug release within depot systems over a prolonged period of time. The use of liposome for the delivery of DNA to the lung means that a greater understanding of their use in macromolecular delivery via inhalational route is emerging. The drug molecules can either be encapsulated in aqueous space or intercalated into the lipid bilayer. Liposomes are defined as “simple microscopic vesicles in which an aqueous volume is entirely enclosed by a membrane composed of lipid molecule.” Glycerol-containing phospholipids are most commonly used component of liposomal formulation. Most common Sphingolipids are Sphingomyelin, Glycosphingo lipids. Liposomes without cholesterol are known to interact rapidly with plasma protein such as albumin, transferrin, and macroglobulin. Stability of repulsive interactions with macromolecules is governed mostly by repulsive electrostatic forces.
Development of a novel one-step production system for injectable liposomes under GMP
Published in Pharmaceutical Development and Technology, 2018
Ryo Araki, Takashi Matsuzaki, Ayumi Nakamura, Daisaku Nakatani, Shoji Sanada, Hai Ying Fu, Keiji Okuda, Masaki Yamato, Shota Tsuchida, Yasushi Sakata, Tetsuo Minamino
There are few methods available for injectable liposome production under good manufacturing practices (GMP). Injectable liposome production processes under GMP generally consist of liposome formation, size homogenization, organic solvent removal, liposome concentration control and sterilization. However, these complicated and separate processes make it difficult to maintain scalability, reproducibility and sterility. To overcome these limitations, we developed a novel one-step in-line closed liposome production system that integrated all production processes by combining the in-line thermal mixing device with modified counterflow dialysis. To validate the system, we produced liposomal cyclosporine A (Lipo-CsA) and lyophilized the liposomes. The three independent pilot batches were highly reproducible and passed the quality specifications for injectable drugs, demonstrating that this system could be used under GMP. The accelerated stability test suggested that the liposomes would be stable in long-term storage. This one-step system facilitates a fully automated and unattended production of injectable liposomes under GMP.
A comprehensive review on recent preparation techniques of liposomes
Published in Journal of Liposome Research, 2020
Liposomes (or lipid vesicles) are a versatile platform as carriers for the delivery of the drugs and other macromolecules into human and animal bodies. Though the method of using liposomes has been known since 1960s, and major developments and commercialization of liposomal formulations took place in the late nineties (or early part of this century), newer methods of liposome synthesis and drug encapsulation continue to be an active area of research. With the developments in related fields, such as electrohydrodynamics and microfluidics, and a growing understanding of the mechanisms of lipid assembly from colloidal and intermolecular forces, liposome preparation techniques have been enriched and more predictable than before. This has led to better methods that can also scale at an industrial production level. In this review, we present several novel methods that were introduced over the last decade and compare their advantages over conventional methods. Researchers beginning to explore liposomal formulations will find this resource useful to give an overall direction for an appropriate choice of method. Where possible, we have also provided the known mechanisms behind the preparation methods.
Pharmaceutical liposomal drug delivery: a review of new delivery systems and a look at the regulatory landscape
Published in Drug Delivery, 2016
Claudia Zylberberg, Sandro Matosevic
Liposomes were the first nanoscale drug to be approved for clinical use in 1995. Since then, the technology has grown considerably, and pioneering recent work in liposome-based delivery systems has brought about remarkable developments with significant clinical implications. This includes long-circulating liposomes, stimuli-responsive liposomes, nebulized liposomes, elastic liposomes for topical, oral and transdermal delivery and covalent lipid-drug complexes for improved drug plasma membrane crossing and targeting to specific organelles. While the regulatory bodies’ opinion on liposomes is well-documented, current guidance that address new delivery systems are not. This review describes, in depth, the current state-of-the-art of these new liposomal delivery systems and provides a critical overview of the current regulatory landscape surrounding commercialization efforts of higher-level complexity systems, the expected requirements and the hurdles faced by companies seeking to bring novel liposome-based systems for clinical use to market.
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