The present study is mainly aimed at delivering a drug into the brain via the intranasal route using a liposomal formulation. For this purpose, rivastigmine, which is used in the management of Alzheimer's disease, was selected as a model drug. Conventional liposomes were formulated by the lipid layer hydration method using cholesterol and soya lecithin as lipid components. The concentration of rivastigmine in brain and plasma after intranasal liposomes, free drug and per oral administration was studied in rat models. A significantly higher level of drug was found in the brain with intranasal liposomes of rivastigmine compared to the intranasal free drug and the oral route. Intranasal liposomes had a longer half-life in the brain than intranasally or orally administered free drug. Delivering rivastigmine liposomes through the intranasal route for the treatment of Alzheimer's disease might be a new approach to the management of this condition.
High performance liquid chromatographic method was optimized, developed and validated as per the ICH guidelines. In this study the 20 mM ammonium formate and acetonitrile in the 57:43 ratio were used as mobile phase for the analysis of valsartan. Full factorial design was used to optimize the effect of variable factors. The responses were peak area, tailing factor and number of theoretical plates. The quadratic effect of flow rate and wavelength individually as well as in interaction were most significant (p < 0.0001 and p < 0.0086, respectively) on peak area; the quadratic effect of pH of buffer was also most significant effect (p < 0.0001) on tailing factor (5%) whereas the quadratic effect of flow rate and wavelength individually was significant (p = 0.0006 and p = 0.0265, respectively) on the number of theoretical plates. The high-performance liquid chromatographic separation was performed at the flow rate 1.0 min/mL, UV detector wavelength 250 nm and pH of the buffer 3.0 as optimized parameters using design of experiments. The retention time values of valsartan were found to be 10.177 min. Percent recovery in terms of accuracy for the prepared valsartan nanoparticles was found in the range of 98.57-100.27%.
The major challenge of first pass metabolism in oral drug delivery can be surmounted by directing delivery toward intestinal lymphatic system (ILS). ILS circumvents the liver and transports drug directly into systemic circulation via thoracic duct. Lipid and polymeric nanoparticles are transported into ILS through lacteal and Peyer's patches. Moreover, surface modification of nanoparticles with ligand which is specific for Peyer's patches enhances the uptake of drugs into ILS. Bioavailability enhancement by lymphatic uptake is an advantageous approach adopted by scientists today. Therefore, it is important to understand clear insight of ILS in targeted drug delivery and challenges involved in it. Areas covered: Current review includes an overview of ILS, factors governing lymphatic transport of nanoparticles and absorption mechanism of lipid and polymeric nanoparticles into ILS. Various ligands used to target Peyer's patch and their conjugation strategies to nanoparticles are explained in detail. In vitro and in vivo models used to assess intestinal lymphatic transport of molecules are discussed further. Expert opinion: Although ILS offers a versatile pathway for nanotechnology based targeted drug delivery, extensive investigations on validation of the lymphatic transport models and on the strategies for gastric protection of targeted nanocarriers have to be perceived in for excellent performance of ILS in oral drug delivery.
Zidovudine-Chitosan microspheres were prepared by a suspension cross-linking method. The chitosan was dissolved in 2% acetic acid solution and this solution was dispersed in the light liquid paraffin. Span-80 was used as an emulsifier and glutaraldehyde as cross-linking agent. The prepared microspheres were slight yellow, free flowing and characterized by drug loading, infrared spectroscopy (IR), differential scanning colorimetry (DSC) and scanning electron microscopy (SEM). The in-vitro release studies are performed in pH 7.4 buffer solution. Microspheres produced are spherical and have smooth surfaces, with sizes ranging between 60-210 µm, as evidenced by SEM and particle size analysis. The drug loaded microspheres showed up to 60% of entrapment and release was extended up to 18-24 h. Among all the systems studied, the 35% Glutaraldehyde crosslinked, microspheres with 1 : 6 drug/chitosan ratio showed 75% release at 12 h. The infrared spectra and DSC thermograms showed stable character of zidovudine in the drug loaded microspheres and revealed the absence of drug-polymer interactions. Data obtained from in vitro release were fitted to various kinetic models and high correlation was obtained in the Higuchi model. The drug release was found to be diffusion controlled.
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