Formulation and Optimization of Zidovudine Niosomes

Abstract

Abstract. Zidovudine (AZT) is commonly used to treat patients with AIDS, but it is limited by toxicity and high dosing needs. Alternative formulations have been proposed to overcome these drawbacks. The objective of this study was to evaluate process-related variables like hydration and sonication time, rotation speed of evaporation flask, and the effects of charge-inducing agent and centrifugation on zidovudine entrapment and release from niosomes. Formulation of zidovudine niosomes was optimized by altering the proportions of Tween, Span and cholesterol. The effect of process-related variables like hydration time, sonication time, charge-inducing agent, centrifugation and rotational speed of evaporation flask on zidovudine entrapment and release from niosomes was evaluated. The effect of changes in osmotic shock and viscosity were also evaluated. Non-sonicated niosomes were in the size range of 2-3.5 μm and sonicated niosomes formulated with Tween 80 and dicetylphosphate (DCP) had a mean diameter of 801 nm. Zidovudine niosomes formulated with Tween 80 entrapped high amounts of drug and the addition of DCP enhanced drug release for a longer time (88.72% over 12 h). The mechanism of release from Tween 80 formulation was the Fickian type and obeyed first-order release kinetics. Niosomes can be formulated by proper adjustment of process parameters to enhance zidovudine entrapment and sustainability of release. These improvements in zidovudine formulation may be useful in developing a more effective AIDS therapy.

Ascorbyl palmitate/DSPE-PEG nanocarriers for oral iron delivery: Preparation, characterisation and in vitro evaluation

“…Iron entrapment in ascorbyl palmitate nanocarriers was determined by centrifugation followed by quantification analysis [32]. Aliquots of nanocarrier dispersions were subjected to ultracentrifugation (11336 g, 60 minutes, 4 ºC) in a refrigerated laboratory centrifuge (Heraeus Fresco 70, Thermo Fisher, UK).…”

A novel approach to oral iron delivery using ferrous sulphate loaded solid lipid nanoparticles

“…Iron incorporation in SLN's was determined by particle ultrafiltration followed by quantification based on methods described previously (Nepal et al 2007;Ruckmani and Sankar, 2010). Briefly, SLN dispersions were centrifuged at high speed (13,000 rpm, 30 minutes, 4 °C); aliquots of the supernatant were then withdrawn and used to measure unincorporated iron spectrophotometrically using a modified ferrozine assay developed in our laboratory (Zariwala et al, in press).…”

Niosomes: a review of their structure, properties, methods of preparation, and medical applications

“…In another study, niosomes manufactured with Tween 80 were able to encapsulate a high amount of AZT, and addition of dicetyl phosphate enhanced drug release for a prolonged period (88.72% over 12 h). Changes in the micromolar ratios of nonionic surfactants with a constant ratio of cholesterol during the preparation of niosomes were associated with the changes in the encapsulation efficiency and controlled release of AZT [56].…”