Niosome

Drug targeting is the ability to direct a therapeutic agent specifically to desired site of action with little or no interaction with nontarget tissue. Niosomes are one of the best carriers for drug targeting. Niosomes are microscopic lamellar structures formed on admixture of non-ionic surfactant of the alkyl or dialkyl polyglycerol ether class and cholesterol with subsequent hydration in aqueous media. Niosomes are biodegradable, relatively nontoxic, more stable and inexpensive, an alternative to liposomes. Niosomes can be SUV (Small Unilamellar Vesicles), MLV (Multilamellr Vesicles) or LUV (Large Unilamellar Vesicles). The method of preparation of niosome is the based on liposome technology. The basic process of preparation is the same i.e. hydration of the lipid phase by aqueous phase. Niosomes are characterized by vesicle size, bilayer formation, number of lamellae, membrane rigidity and entrapment efficiency. A method of in-vitro release rate study includes the use of dialysis tubing. Niosomal drug delivery is potentially applicable to many pharmacological agents for their action against various diseases including cancer and leishmaniasis.

  The present research work aimed at development and optimization of niosome based gel (NBG) for the vaginal delivery of Tenofovir disoproxil fumarate (TDF). The TDF was   incorporated into niosomes using span 60 and cholesterol. Box-Behnken statistical screening design with 3 factors, 3 levels, and 15 runs was selected to statistically optimize the formulation parameters. The independent variables selected were parts of cholesterol (X1), surfactant loading (X2), amount of stabilizer (X3). Fifteen batches were prepared by thin film hydration method and evaluated for percentage drug entrapment (PDE) and vesicle size. The transformed values of the independent variables and the PDE (dependent variable) were subjected to multiple regressions to establish a full-model second-order polynomial equation. F value was calculated to confirm the omission of insignificant terms from the full-model equation to derive a reduced-model polynomial equation to predict the PDE of niosome. A model was validated for accurate prediction of the PDE by performing checkpoint analysis. The niosomal dispersion was incorporated in to Carbopol 940NF gel. The NGB was evaluated for drug content, pH, spreadability, consistency and texture analysis. The in-vitro drug release study shows sustained release gel effect whereas the in-vivo study shows no signs of irritation on the applied vaginal site in rat. The gel was kept for 6 weeks accelerated stability studies. The niosomes and niosomal gel showed maximum stability at 2 to 8 °C.   Key-words: Niosome, vaginal drug delivery, Tenofovir disoproxil fumarate, span 60, Box Behnken design