A perspective overview on lipospheres as lipid carrier systems

Both hydrophilic and lipophilic therapeutics can be delivered successfully into deep and peripheral tissues such as cerebrospinal fluid and central nervous system by encapsulating them with crystalline lipids as lipospheres. The advent of lipospheres was meant to deliver both therapeutic moieties with enhanced efficacy and added stability to reach out intended tissue areas. Although extensive information is available on physicochemical, analytical and biopharmaceutical aspects of lipospheres, there was no specific order pertaining to critical composition and rationale of component selection available for academic and pilot scale processing of lipospheres. With the interest of compiling key points in a typical formulation of lipid lipospheres, this article was intrigued to discuss melt method, co-solvent, microemulsion, super critical fluid, spray drying and spray congealing techniques that were employed to scale up lipospheres. The selection criteria for both the drugs and lipids in liposphere formulations were demonstrated here. The quality assessment with variables like loading capacity and entrapment efficiency was explained. A note on preliminary screening factors to determine the liposphere formation such as liposphere dimensions with morphological scenario was detailed in this article. This article also includes the stability and storage issues with reference to photolysis. The marked differential in enhancing solubility and permeability characteristics of Class II and IV drug candidates by liposphere delivery systems with an evident of in vivo outcomes were emphasized.

Cubosomes as targeted drug delivery systems - a biopharmaceutical approach

Cubosomes are reversed bicontinuous cubic phases and possess unique physicochemical properties. These special systems are receiving much attention for the delivery of various hydrophilic, hydrophobic and amphiphilic drugs with enhanced bioavailability and high loading capacity. A wide variety of drugs are applicable for cubosome formulation for various routes of delivery. The lipids used in cubosome formulation are more stable and offer stability to the formulation during shelf-life. The article reviews about the back ground, techniques of cubosome preparation such as high pressure homogenization, probe ultrasonication and automated cubosome preparation; and also methods of cubosomes preparation such as top down, bottom up and other methods with pictorial presentation. This article emphasizes the phase transition and also targeted approaches of cubosomes. The characterization studies for cubosomes such as cryo transmission electron microscopy, differential scanning calorimetry and scanning electron microscopy followed by in-vitro and in-vivo evaluation studies of cubosomes were explained with appropriate examples. Recent applications of cubosomes were explained with reference to flurbiprofen, odorranalectin, diazepam and dexamethasone. The advantages, disadvantages and limitations of cubosomal technology were emphasized.

Microemulsions based transdermal drug delivery systems

Since the discovery of microemulsions by Jack H Schulman, there has been huge progress made in applying microemulsion systems in plethora of research and industrial process. Microemulsions are optically isotropic systems consisting of water, oil and amphiphile. These systems are beneficial due to their thermodynamic stability, optical clarity, ease of preparation, higher diffusion and absorption rates. Moreover, it has been reported that the ingredients of microemulsion can effectively overcome the diffusion barrier and penetrate through the stratum corneum of the skin. Hence it becomes promising for both transdermal and dermal drug delivery. However, low viscosity of microemulsion restrains its applicability in pharmaceutical industry. To overcome the above drawback, the low viscous microemulsions were added to viscous gel bases to potentiate its applications as topical drug delivery systems so that various drug related toxic effects and erratic drug absorption can be avoided. The present review deals with the microemulsions, various techniques involved in the development of organic nanoparticles. The review emphasized on microemulsion based systems such as hydrogels and organogels. The physicochemical characteristics, mechanical properties, rheological and stability principles involved in microemulsion based viscous gels were also explored.