liposome

Lyophilization is promising approach to increase the shelf life of liposome. The major limitation in the widespread use of liposome is its instability. The aim of this study was to investigate the effect of lyophilization either in the presence or in the absence of lyoprotectant on liposome properties Lyophilization is used to ensure an increased shelf life of liposomes by preserving them in dry state more stable than the aqueous dispersion. When stored as aqueous system the encapsulated drugs are released & the liposome might aggregate or fuse. The process of lyophilization without cryoprotectant resulted in particle size increased & significant content leakage. This review work suggests that the investigation of stability of lyophilized liposomes containing PC (Phosphatidyl Choline) & cholesterol. Liposomes sphere-shaped vesicles consisting of one or more phospholipids bilayer in which both hydrophilic & hydrophobic drug entity can be incorporated. Due to their size & hydrophobic & hydrophilic character liposomes are promising for drug delivery. This structure turns liposomes into ideal drug carriers, since hydrophilic drugs tend to entrapped in the core; while hydrophobic ones will be entrapped within the lipid bilayers. Liposome is one of the most successful drug delivery system applying nanotechnology to potentiate the therapeutic efficacy & reduce toxicities of conventional medicines. The encapsulation efficiency partially depends upon the logP of drug. Lyophilization is a strategy often employed to improve liposomal formulation stability, due to reactivity being far less pronounced in the solid versus aqueous state.

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.