Niosomes

The Improvement in the nanotechnology brings revolutionary changes & helps in preparing the novel formulations. The proniosomes are solid colloidal particles which may be hydrated immediately before use to yield the aqueous niosome dispersions similar to those that are produced by more cumbersome conventional methods. These proniosomes minimize the problems of niosome physical stability such as leaking, aggregation & fusion provide additional convenience in dosing, transportation, storage & distribution. The proniosomes overcome the disadvantages involved with liposomal & niosomal drug delivery systems. This review focuses on different aspects of proniosome such as components , types, preparation, evaluation & applications.

Nonionic surfactant vesicles (niosomes) were formulated with an aim of enhancing the oral bioavailability of Decitabine, an anti-cancer drug. Niosomes were formulated by conventional thin film hydration technique with different molar ratios of surfactant, cholesterol and dicetyl phosphate. The formulated niosomes were found spherical in shape, ranging from 2.95 𝜇m to 10.91 𝜇m in size. Vesicles with 1 : 1 : 0.1 ratios of surfactant : cholesterol : dicetyl phosphate with each grade of span were found to have higher entrapment efficiencies, which were further selected for in vitro studies. Vesicles formulated with sorbitan monostearate were found to have maximum drug release (99.091%) at the end of 24 hours and followed zero order release kinetics. In conclusion, noisome could be a promising delivery for Decitabine with improved oral bioavailability and prolonged release profiles.

Present study has been an effort towards improving the skin penetration of Minoxidil by encapsulating it in niosomes. Niosomal formulations of Minoxidil were prepared by thin film hydration method using two different surfactants like sorbitan monoesters (span 40, 60) and polysorbate (tween 60) with cholesterol. The prepared niosomes were evaluated for size, shape, entrapment efficiency and in-vitro drug release. Niosomes were spherical in shape and size range was found to be 4.10±1.05 to 6.74±2.99 μm. The entrapment efficiency was found in the range of 36.74±0.84 to 61.16±0.36 % at the end of 24hrs. Among all the Minoxidil niosomes the promising formulation were found to be of span 60 and cholesterol in the ratio of 1:0.2 and were incorporated into carbopol gel. The prepared gel was characterised for appearance, pH, drug content, viscosity and in-vitro drug release. The in-vitro drug release study was carried out using phosphate buffer saline (PBS) pH 7.4 and was found to be 42.16±1.94% at the end of 12 hrs.

The main objective of the study is to formulate emtricitabine, a nucleoside reverse transcriptase inhibitor used in the treatment of Human Immuno deficiency Virus (HIV) infections as a niosomal formulation to improve the Central Nervous System (CNS) penetration of the drug and evaluate its CNS penetration using in vitro blood-brain barrier penetration study using immobilized artificial membrane phosphatidylcholine column chromatography. Emtricitabine encapsulated niosomes were prepared by thin layer evaporation (TLE)-paddle stirring method with Span 60 as main surfactant. Cholesterol (CHL), Solulan C24 (SOL) and N-palmitoyl glucosamine (NPG) were also included in the niosomal formulations. The ratio of Span 60:CHL:SOL:NPG was 50:40:10:10 with total concentration of components as 38 mM.  The hydration temperature was maintained at 65 0C. Sonication method was employed for size reduction of the niosomes. The formulation was evaluated for CNS penetration by in vitro blood-brain barrier penetration study using immobilized artificial membrane phosphatidylcholine column chromatography. The Scanning electron microscopic images showed good formation of the niosomal vesicles. The mean particle size and encapsulation efficiency were found to be 154±4 nm and 64.45±1.14% respectively. In vitro blood-brain barrier (BBB) penetration of emtricitabine from drug loaded NPG niosomes using immobilized artificial membrane phosphatidylcholine column chromatography showed an improved CNS penetration of the drug with (kIAM/MW4) X 1010 values of 2.79±0.05 at pH 5.5 and 8.48±0.18 at pH 7.0. The results showed an increased CNS penetration when the drug was encapsulated in niosomes and may be considered as a potential alternative to improve brain targeting of emtricitabine and thus minimize HIV Associated Neurocognitive Disorders (HAND).

The aim of present study was to design and development of a proniosomal transdermal drug delivery system of lornoxicam for the treatment of rheumatoid arthritis and enhanced skin targeting effect, sustained & prolonged drug release, enhanced skin bioavailability by using different type of non ionic surfactant & cholesterol. Proniosomes of Lornoxicam were prepared by coacervation-phase separation method. The formulation systems were characterized in vitro for size, vesicle count, drug entrapment, drug release profile and vesicular stability. The method used for preparing proniosome resulted in an encapsulation yield of 67.71-87.64%. Proniosomes were characterized by transmission electron microscopy. In vitro studies showed prolonged release of entrapped lornoxicam. A successful attempt was made to develop proniosomal gel for transdermal delivery of lornoxicam using different grades of nonionic surfactant.

The proniosomal approach helps to solve the problem regarding stability and provides higher entrapment efficiency over conventional system. Proniosomal gel is a liquid crystalline- compact niosomal hybrid which is prepared by dissolving surfactant in small amount of suitable solvent and least amount of aqueous phase. This compact gel can be converted to niosomes hydration. Proniosomes can entrap hydrophilic as well as lipophillic drugs. Proniosomal gel offers a versatile vesicle drug delivery concept with potential for drug delivery via transdermal rout. Over the last few years an inclusive research has been done over pro-vesicular approach for transdermal drug delivery. Skin has a very tough diffusion barrier inhibiting penetration of drug moiety which is rate limiting barrier for penetration of drugs. There are several approaches that deal with penetration enhancement across the skin. Vesicular and provesicular systems are promising amongst them. Vesicular systems including (niosomes, ethosomes, transfersomes and liposomes) are promising systems to cross this permeation barrier.

Over the last few years an inclusive research has been done over provesicular approach for transdermal drug delivery. Skin has a very tough diffusion barrier inhibiting penetration of drug moiety which is rate limiting barrier for penetration of drugs. There are several approaches that deal with penetration enhancement across the skin. Vesicular and provesicular systems are promising amongst them. Vesicular systems including (niosomes, ethosomes, transfersomes and liposomes) are promising systems to cross this permeation barrier. The proniosomal approach helps to solve the problem regarding stability and provides higher entrapment efficiency over conventional system. Proniosomal gel is a liquid crystalline- compact niosomal hybrid which is prepared by dissolving surfactant in small amount of suitable solvent and least amount of aqueous phase. This compact gel can be converted to niosomes hydration. Proniosomes can entrap hydrophilic as well as lipophillic drugs. Proniosomal gel offers a versatile vesicle drug delivery concept with potential for drug delivery via transdermal rout.

Conventional liquid ophthalmic formulations are most convenient from patient point of view. But these formulation shows low bioavailability because of a constant lachrymal drainage in the eye which leads to frequent dosing. Moreover, the absorption of the drug drained through the nasolacrymal duct may result in undesirable side effects. To overcome these limitation different approaches has been applied such as ointment, gel, cream etc. These ophthalmic formulations also fails to show desired therapeutic responses because of their own disadvantages such as ointment makes blurred vision. So two different systems was combined together as niosomes and in-situ gel by incorporating niosomes in in-situ gel formulation so that it is easy to administered and retain at the site for prolong period of time. The Ofloxacin (OFL), a second generation fluoroquinolone derivative used in eye infections needs frequent dosing in its solution form. Vesicular system reported prolonged and controlled action at corneal surface but it has again limitation of drainage along tear produced.  In this, first niosomes containing ofloxacin were prepared by applying 32 full factorial designs and evaluated for its vesicle size, percent entrapment, in-vitro drug release kinetics and their stability. Also in-situ gel formulation was prepared by dispersing the niosomes in solution of carbopol 940 and Hydroxy Propyl Methyl Cellulose (HPMC) K4M. In-vitro drug release kinetics from niosomal in-situ gel formulation indicates that the minimum inhibitory concentration (MIC) of drug (4 μg/ml) was achieved within 1-2 hrs (batch G1-G9).

  Colloidal Drug Delivery system is an advancing technology expected to bring revolutionary changes in the field of pharma and health sciences including drug delivery, diagnostics and treatment. The advancement in colloidal drug delivery systems helps in preparing newer formulations which become useful for treatment of tuberculosis. Development of Metered dose inhaler (MDT) and Directly Observed Therapy (DOTS) also proves to helpful in treatment of tuberculosis. Various colloidal drug delivery systems liposomes, niosomes, nanoparticles and microparticles proves to be a successful tool for tuberculosis treatment. One of the preparations like microemulsions results in theimprovement of bioavailability of the drugs. Similarly corticosteroids also found to be an interesting tool here because corticosteroids reduced the risk of pleural thickening in tuberculosis patients. These various colloidal drug delivery systems minimize the problems of conventional therapy like poor penetration, drug resistance, systemic toxicity and also main the improved drug delivery. This article describes the applications of various formulations along with their future aspects in treatment of tuberculosis.