Preparation, in Vitro and in Vivo Evaluation of Liposomal/Niosomal Gel Delivery Systems for Clotrimazole
Clotrimazole, which is an imidazole derivative antifungal agent, was widely used for the treatment of mycotic infections of the genitourinary tract. To develop alternative formulation for the vaginal administration of clotrimazole to provide sustained and controlled release of appropriate drug for local vaginal therapy, liposomes/niosomes were evaluated as delivery vehicles. To optimize the preparation of liposomes/niosomes with regard to size and entrapment efficiency, multilamellar liposomes/niosomes containing drug were prepared by lipid hydration method. The prepared liposomes/niosomes were incorporated into 2% carbopol gel, and the systems were evaluated for drug stability in phosphate-buffered saline (pH 7.4) and simulated vaginal fluid at 37 +/- 1 degrees C. Further, the vesicle gel system was evaluated by antifungal activity and tolerability on tissue level in rat.
Available from: Hosseinali Tabandeh
- "Similar results have previously been reported for some lipophilic drugs as triamcinolone acetonide (36), clotrimazole (37), ciprofloxacin (38), dexamethasone (39), ibuprofen and diazepam (40). Cholesterol molecules are placed between the adjacent phospholipid molecules in liposomal bilayer and hence occupy some space and compete with α-tocopherol for incorporation into the bilayer. "
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ABSTRACT: Vitamin E (α-tocopherol) is a natural antioxidant very useful for preventing the harmful effects of UV sun rays as skin aging and cancers. In this study, different MLV formulations were made using egg lecithin and varying molar ratios of α-tocopherol and/or cholesterol, and their encapsulation efficiencies were determined. The best liposomal product was incorporated into a carbomer 980 gel. The resulting preparation was then studied with regard to the rheology and release profile using r(2) values and Korsmeyer-Peppas equation. The encapsulation efficiency was dramatically decreased when using α-tocopherol at molar ratios of 1:10 or more, which is suggested to be due to the defect in regular linear structure of the bilayer membrane. Addition of cholesterol to formulations caused a decrease in encapsulation efficiency directly related to its molar ratio, which is due to the condensation of the bilayer membrane as well as competition of cholesterol with α-tocopherol. The liposomal gel showed a yield value of 78.5 ± 1.8 Pa and a plastic viscosity of 27.35 ± 2.3 cp. The release showed a two-phase pattern with the zero-order model being the best fitted model for the first phase. However, the "n" and r(2) values suggested a minor contribution of Higuchi model due to some diffusion of α-tocopherol from the outermost bilayers of the MLVs to the gel. The second phase showed a non-Fickian release indicating a more prominent role for diffusion. This combinational release profile provides a high initial concentration of α-tocopherol followed by a slow release throughout a 10 h period.
Available from: L.K. El-Khordagui
- "[informa internal users] At: 15:34 7 May 2009 (also shown in Figure 4) compared with the niosome gel, but the extent of release at 12 h was comparable. Incorporation of the niosomes into a structured gel vehicle resulted in a slower initial phase compared with niosome dispersion possibly because of the diffusion restriction imposed by the polymeric network of the gel (Glavas-Dodov, Fredro- Kumbaradzi, Goracinova, Calis, & Hincal, 2003; Ning et al., 2005; Turker, Erdogan, Ozer, Ergun, & Tuncel, 2005). "
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ABSTRACT: Marketed topical gels of the antifungal drug naftifine hydrochloride contain 50% alcohol as cosolvent. Repeated exposure to alcohol could be detrimental to skin. The aim of this study is to develop an alcohol-free niosome gel containing 1% naftifine hydrochloride. Niosomes were prepared and formulation variables were optimized to achieve maximum entrapment coupled with stability. Maximum drug entrapment and niosome stability entailed imparting a negative charge to the vesicles where entrapment efficiency reached 50%. Niosomes were incorporated into a hydroxyethylcellulose gel. The final gel contained a total drug concentration of 1% (wt/wt) half of which was entrapped in the niosomes. The results suggest the potential usefulness of the niosome gel.
Available from: Dalia Shaker
- "However, most of the studies were limited to in vitro characterization and release studies, and there rarely were any data showing the in vivo performance of these systems. In one study, Ning et al. (2005) evaluated the efficacy of using a clotrimazole-inliposomes-in-carbopol gel system to deliver the clotrimazole vaginally and found that the liposomal gel system was more effective in treating yeast in rat vagina, compared to a commercial clotrimazole ointment (Ning et al., 2005). However, the activity of the clotrimazole-in-liposomes without the carbopol gel was not reported, making it impossible to know whether the liposomal gel system had prolonged the retention of the clotrimazole locally. "
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ABSTRACT: Gadolinium neutron capture therapy (Gd-NCT) is a promising approach to fight cancer. One key factor for the success of Gd-NCT is to deliver and maintain a sufficient amount of Gd inside tumors. A large amount of Gd can be readily introduced into tumors by direct intratumor injection. However, an innovative approach is needed to maintain the Gd in the tumors. We encapsulated a Gd compound into a liposome formulation and then dispersed the liposomes into a thermo-sensitive polymeric gel. In murine tumor models, we showed that this liposome-in-thermo-sensitive gel system significantly extended the retention of the Gd compound in tumors. This similar concept may be applied to prolong the retention of other cytotoxic chemicals in tumors, and thus, improve their anti-tumor efficacy.
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