Self-assembled drug delivery systems. Part 8: In vitro / in vivo studies of the nanoassemblies of cholesteryl-phosphonyl gemcitabine

Overcoming the delivery barrier of oligonucleotide drugs and enhancing nucleoside drug efficiency: The use of nucleolipids

With the rapid development of synthetic technology and biological technology, many nucleic acid-based drugs have entered the clinical trials. However, their inherent disabilities in actively and efficiently penetrating cell membranes still severely restrict their further application. The main drawback of cationic lipids, which have been widely used as nonviral vectors of nucleic acids, is their high cytotoxicity. A series of nucleoside-based or nucleotide-based nucleolipids have been reported in recent years, due to their oligonucleotide delivery capacity and low toxicity in comparison with cationic lipids. Lipophilic prodrugs of nucleoside analogs have extremely similar structures with nucleolipid vectors and are thus helpful for improving the transmembrane ability. This review introduces the progress of nucleolipids and provides new strategies for improving the delivery efficiency of nucleic acid-based drugs, as well as lipophilic prodrugs of nucleosides or nucleotides for antiviral or anticancer therapies.

Prodrugs, phospholipids and vesicular delivery - An effective triumvirate of pharmacosomes

With the advent from the laboratory bench to patient bedside in last five decades, vesicular systems have now come to be widely accepted as pragmatic means for controlled delivery of drugs. Their success stories include those of liposomes, niosomes and even the lately developed ethosomes and transferosomes. Pharmacosomes, which, as delivery systems offer numerous advantages and have been widely researched, however, remain largely unacknowledged as a successful delivery system. Though a large number of drugs have been derivatized and formulated into self-assembled vesicular systems, the term pharmacosomes has not been widely used while reporting them. Therefore, their relative obscurity may be attributed to the non-usage of the nomenclature of pharmacosomes by the researchers working in the area. We present a review on the scenario that lead to origin of these bio-inspired vesicles composed of self-assembling amphiphilic molecules. Various drugs that have been formulated into pharmacosomes, their characterization techniques, their properties relative to those of other vesicular delivery systems, and the success achieved so far are also discussed.

Self-assembling prodrugs

Covalent modification of therapeutic compounds is a clinically proven strategy to devise prodrugs with enhanced treatment efficacies. This prodrug strategy relies on the modified drugs that possess advantageous pharmacokinetic properties and administration routes over their parent drug. Self-assembling prodrugs represent an emerging class of therapeutic agents capable of spontaneously associating into well-defined supramolecular nanostructures in aqueous solutions. The self-assembly of prodrugs expands the functional space of conventional prodrug design, affording a possible pathway to more effective therapies as the assembled nanostructure possesses distinct physicochemical properties and interaction potentials that can be tailored to specific administration routes and disease treatment. In this review, we will discuss the various types of self-assembling prodrugs in development, providing an overview of the methods used to control their structure and function and, ultimately, our perspective on their current and future potential.

Building Nanostructures with Drugs

The convergence of nanoscience and drug delivery has prompted the formation of the field of nanomedicine, one that exploits the novel physicochemical and biological properties of nanostructures for improved medical treatments and reduced side effects. Until recently, this nanostructure-mediated strategy considered the drug to be solely a biologically active compound to be delivered, and its potential as a molecular building unit remained largely unexplored. A growing trend within nanomedicine has been the use of drug molecules to build well-defined nanostructures of various sizes and shapes. This strategy allows for the creation of self-delivering supramolecular nanomedicines containing a high and fixed drug content. Through rational design of the number and type of the drug incorporated, the resulting nanostructures can be tailored to assume various morphologies (e.g. nanospheres, rods, nanofibers, or nanotubes) for a particular mode of administration such as systemic, topical, and local delivery. This review covers the recent advances in this rapidly developing field, with the aim of providing an in-depth evaluation of the exciting opportunities that this new field could create to improve the current clinical practice of nanomedicine.

Molecular self-assembly of amphiphilic cyclic phosphoryl gemcitabine with different N-fatty acyl tails and enhanced anticancer effects of the self-assembled nanostructures

Molecular self-assembly of nucleosides is important, and the self-assembled nanostructures may be used for drug delivery and targeting. Gemcitabine (GEM) is an important anticancer nucleoside analog though deactivation and multi-drug resistance frequently happen. Four N-fatty acyl derivatives of cyclic phosphoryl GEM were prepared based on the theory of self-assembled drug delivery systems and the HepDirect prodrug technique wherein the prodrug could be degraded by the cytochrome P450 isozymes in hepatocytes to release active drugs. They are cyclic phosphoryl N-octyl gemcitabine (CPOG), cyclic phosphoryl N-dodecanoyl gemcitabine (CPDG), cyclic phosphoryl N-hexadecanoyl gemcitabine (CPHG), and cyclic phosphoryl N-octadecanoyl gemcitabine (CPODG). Their amphiphilicity and self-assembling property were explored. The self-assembled nanostructures of them were prepared and simulated. The in vitro anticancer activities of the nanostructures were investigated. The derivatives formed the Langmuir monolayers at the air/water interface, though their surface pressure-molecular area isotherms were different with dependency of the length of lipid chains. The derivatives self-assembled into the vesicular or rice-like nanostructures based on the hydrophobic interaction between lipid chains when injected into water, in accordance with the results of computer simulation. The nanostructures showed higher anticancer effects on HepG2 cells than GEM. The nanostructures are promising anticancer nanomedicines.