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.
"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. "
[Show abstract][Hide abstract] 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.
Iranian journal of pharmaceutical research (IJPR) 02/2013; 12(Suppl):21-30. · 1.07 Impact Factor
"[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). "
[Show abstract][Hide abstract] 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.
Drug Development and Industrial Pharmacy 12/2008; 35(5):631-7. DOI:10.1080/03639040802498864 · 2.10 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Superficial fungal infections are among the most widespread diseases known to man. They target parts of the body as diverse in form and function as the skin, the nail, the buccal cavity, the eye and the vagina. Fungistatic azole drugs, that is, imidazole- and triazole-containing compounds (e.g. miconazole and itraconazole, respectively), have been the mainstay of antifungal therapy for many years. The polyene nystatin is effective in treating Candida infections but is inactive against cutaneous dermatophytes. The advent of the fungicidal allylamines (e.g. terbinafine) and their congeners (e.g. butenafine) has improved treatment options: the course of therapy is shorter and cure rates higher with fungicidal drugs. Other newer agents include the echinocandins (e.g. caspofungin) that are primarily intended for systemic administration but which may have a role in topical therapy. In order to elicit a pharmacologic response following topical administration, these agents must enter into and diffuse across the target biologic tissues, which have distinct architectures and compositions depending on their function. The rate and extent of transport will depend on the interplay between the drug's molecular properties and the characteristics of the biologic tissue. The drug may also interact with specific proteins or other membrane components. These interactions can prolong residence time and therapeutic effect; for example, azoles have an affinity for keratin (as do dermatophytes, their therapeutic target). Drug properties that increase permeability across a given membrane may render the molecule less effective at another biologic tissue; for example, the stratum corneum is a lipidic barrier, whereas the keratin-rich nail contains 10-fold less lipid and is perhaps best viewed as a hydrogel with very low lipid content. Consequently, both offer very different environments and drug delivery challenges compared with the oral and vaginal mucosae. In light of this, it is clear that formulation design and optimization are key steps in increasing the therapeutic efficacy of topical antifungal therapy. Furthermore, the formulation, which is the primary interface with the membrane, must not only be optimized with respect to the drug but also be compatible with the biologic tissue. Thus, developing effective formulations for topical therapy is a complex task. In this review, we provide a brief description of newer approaches in topical antifungal drug development and present a survey of recent work.
American Journal of Drug Delivery 12/2005; 4(4):231-247. DOI:10.2165/00137696-200604040-00006
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