The aim of the present study was to formulate and evaluate the ritonavir-loaded stealth liposomes by using 3 2 factorial design and intended to delivered by parenteral delivery. Liposomes were prepared by ethanol injection method using 3 2 factorial designs and characterized for various physicochemical parameters such as drug content, size, zeta potential, entrapment efficiency and in vitro drug release. The optimization process was carried out using desirability and overlay plots. The selected formulation was subjected to PEGylation using 10 % PEG-10000 solution. Stealth liposomes were characterized for the above-mentioned parameters along with surface morphology, Fourier transform infrared spectrophotometer, differential scanning calorimeter, stability and in vivo pharmacokinetic studies in rats. Stealth liposomes showed better result compared to conventional liposomes due to effect of PEG-10000. The in vivo studies revealed that stealth liposomes showed better residence time compared to conventional liposomes and pure drug solution. The conventional liposomes and pure drug showed dose-dependent pharmacokinetics, whereas stealth liposomes showed long circulation half-life compared to conventional liposomes and pure ritonavir solution. The results of statistical analysis showed significance difference as the p value is (\0.05) by one-way ANOVA. The result of the present study revealed that stealth liposomes are promising tool in antiretroviral therapy.

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Statins are HMG-CoA reductase inhibitors, which lower the cholesterol level through reversible and competitive inhibition; they are involved in the biosynthesis of cholesterol and other sterols. Simvastatin exhibits poor oral bioavailability (<5%) and undergoes extensive microsomal metabolism by CYP enzymes. CYP3A4 is the major metabolizing enzyme that metabolizes lactone form of simvastatin and significantly lowers intestinal uptake. The hydrophobic properties of simvastatin prevent complete dissolution of the drug in the intestinal fluid which also contributes to its lower bioavailability. SLNs are alternative carrier system to polymeric nanoparticles. SLNs are in submicron size range (1–1000 nm). To overcome the hepatic first pass metabolism and to enhance the bioavailability, intestinal lymphatic transport of drugs can be exploited. In the present study, attempt has been made to prepare solid lipid nanoparticles of simvastatin to improve the bioavailability. SLNs of simvastatin were prepared with Trimyristin by hot homogenization followed by ultrasonication method. The SLNs were characterized for various physicochemical properties and analytical techniques like PXRD, DSC to study thermal nature and morphology of formulation and excipients. Promising results of the study indicated the applicability of simvastatin solid lipid nanoparticles as potential tools for improvement of bioavailability of poorly soluble drugs.

The prolonged retention of drug by the gum karaya gel loaded with liposomal dispersion could effectively exhibit the antifungal activity for prolonged periods for cutaneous delivery.