Date Published: December 11, 2018
Author(s): Mahmoud Gharbavi, Jafar Amani, Hamidreza Kheiri-Manjili, Hossein Danafar, Ali Sharafi.
Niosomes (the nonionic surfactant vesicles), considered as novel drug delivery systems, can improve the solubility and stability of natural pharmaceutical molecules. They are established to provide targeting and controlled release of natural pharmaceutical compounds. Many factors can influence on niosome construction such as the preparation method, type and amount of surfactant, drug entrapment, temperature of lipids hydration, and the packing factor. The present review discusses about the most important features of niosomes such as their diverse structures, the different preparation approaches, characterization techniques, factors that affect their stability, their use by various routes of administration, their therapeutic applications in comparison with natural drugs, and specially the brain targeting with niosomes-ligand conjugation. It also provides recent data about the various types of ligand agents which make available active targeting drug delivery to the central neuron system. This system has an optimistic upcoming in pharmaceutical uses, mostly with the improving availability of innovative schemes to overcome blood-brain barrier and targeting the niosomes to the brain.
Several brain and CNS diseases such as neurological diseases (meningitis, encephalitis, viral, bacterial, protozoan, and fungal and worm infections), neurological disorders (epilepsy, seizures, trauma, Parkinson, multiple sclerosis, dementia, Alzheimer, mononeuropathy, polyneuropathy, and myopathy), and brain tumors (cerebral tumors and glioma) are associated with mortality. These problems needed proper drug delivery for treatment . Several approaches to create novel CNS drug-delivery systems are primarily due to the anatomical and physiological characteristics of the blood-brain barrier (BBB) [2–4]. Neural tissues of the brain are protected in contradiction of neurotoxic agents and variation in blood structure that are important for regular purpose of the neurons that covered through BBB. Most organs in our body, apart from the brain and spinal cord, are perfused by capillaries lined with endothelial cells which need small pores to let the small molecules move fast into the organ interstitial fluid from the circulation . In the brain arteriole, ECs are connected to each other by continuous tight junctions (TJs), known as zonula occludens, which cover the paracellular pathway [6, 7]. This can efficiently block the free polar solutes from paracellular pathways and so cast off admission to brain interstitial fluid. Therefore, the BBB let the small particles to break over the brain through the blood stream such as lipophilic solutes or those that pass in the brain by an active transport apparatus, mainly with crucial nutrients, precursors, and cofactors [8–11]. BBB can be transported into the brain endothelium by several mechanisms, such as BBB peptide transport mechanisms. Previous studies suggest that this mechanism is the principal attitude for drug delivery to the brain. Generally, there are three systems for drug delivery to the brain [8, 12] including systemic absorption through BBB and nasal and intracerebroventricular (ICV) administration. On the other hand, each one of these methods has several disadvantages which are listed below.
Nonionic surfactant vesicles were introduced as an innovative and capable method to natural drug delivery. They are mainly composed of nonionic surfactants and cholesterol, and their inside usually comprise a buffer solution at proper pH. They can be made by different approaches, which affect the establishment and the properties of the medication, cholesterol amount, structure, type, and amounts of surfactant. As a drug delivery method, niosomes are osmotically active, less toxic, and chemically stable. Surface modification is comparatively easy on them, due to the functional groups that can add on their hydrophilic heads. Niosomes active targeting to the desire tissue is arbitrated with several therapeutic means as ligand of the distinctive receptor. This system has an optimistic upcoming in pharmaceutical uses, mainly with the increasing availability of new schemes to overcome BBB and targeting the niosomes to the CNS.