Three months chemoprophylaxis of shistosomiasis using liposome encapsulated oxamniquine

Oxamniquine liposomes of the molar ratio 7:6, neutral and negatively charged, were prepared by the vortex dispersion method. Entrapped oxamniquine was estimated by HPLC analysis. Percentage drug encapsulated was found to range from 12.4% [neutral liposomes] to 20% [negative liposomes]. Drug-free and oxamniquine liposomes were characterized by particle-size analysis and Differential-scanning-calorimetry. Liver disposition of oxamniquine liposomes in mice, three-months post [s.c.] injection was investigated. Results reveal that oxamniquine liposomes are better liver-targeted than the free drug. Chemoprophylaxis of oxamniquine liposomes against S. mansoni in mice, was assessed for three months where drug liposomes displayed highly significant protection of 44%, unlike the free drug preparation; 1.3%. Stability study of oxamniquine liposomes was conducted on negative and neutral liposomes at -10, 4°, and 25°. Neutral liposomes displayed better sustained release of the drug over the negative ones. Storage at -10° provides more stable drug- liposomes. Sterilization of negatively charged oxamniquine liposomes was conducted employing four doses of gamma radiation of 10, 15, 20 and 25 KGy. Results revealed that 25 KGy is the optimum sterilizing dose, in addition to inferring high stability to the product

Release profile of niclosamide from mixed elastomers

A new blend of elastomers containing niclosamide, the most potent molluscicide against snail vectors of schistosomiasis, has been prepared and subjected to in vitro release measurements. The blend consists of 70% natural rubber [NR], and 30% styrene butadiene rubber [SBR] with and without certain additives such as a porosigen [ammonium sulfate] and surfactant [sodium lauryl sulfate SLS] in different concentrations. The results revealed that the biocide release obeys a diffusion controlled mechanism with a complex release pattern, in all samples tested. The presence of SBR in NR matrix has markedly increased the NES release rate, while ammonium sulfate or SLS did not increase the release rate in general. This study indicated that mixing selected elastomers is more useful than the use of additives for developing of compositions possessing a required release rate

Thermodynamics of niclosamide diffusion from elastomeric matrices

Elastomeric compositions containing the molluscicide niclosamide ethanolamine salt [NES], in chloroprene rubber [CR], natural rubber [NR] and styrene-butadiene rubber [SBR] have been subjected to the determination of NES release, at six temperatures, and diffusion constants. Double logarithmic plots fractional release as a function of time indicate that the release mechanism change from Fickian to anomalous [non-Fickian] as the temperature increases. Thermodynamic functions were calculated from the temperature dependence of the diffusion constants, using Arrhenius equation. The activation energy was found to be indirectly proportional to the amount of niclosamide released and to diffusion coefficients. Comparing NR, CR, and SBR, the study revealed that SBR requires the least activation energy to release NES, and possessing the highest NES release rate, under all temperatures tested. This study could represent a guide in calculating the required amounts of controlled release formulations when applied under different temperatures in snail control programs