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Abstract. The purpose of this study was to evaluate the effect of formulation components on the in vitro skin permeation of microemulsion drug delivery system containing fluconazole (FLZ). Lauryl alcohol (LA) was screened as the oil phase of microemulsions. The pseudo-ternary phase diagrams for microemulsion regions were constructed using LA as the oil, Labrasol (Lab) as the surfactant and ethanol (EtOH) as the cosurfactant. The formulation which showed a highest permeation rate of 47.15± 1.12 µg cm −2 h −1 and appropriate physicochemical properties was optimized as containing 2% FLZ, 10%LA, 20% Lab/EtOH (1:1), and 68% double-distilled water (w/w). The efficiency of microemulsion formulation in the topical delivery of FLZ was dependent upon the contents of water and LA as well as Lab/EtOH mixing ratio. It was concluded that the percutaneous absorption of FLZ from microemulsions was enhanced with increasing the LA and water contents, and with decreasing the Lab/EtOH ratio in the formulation. Candida albicans was used as a model fungus to evaluate the antifungal activity of the best formula achieved, which showed the widest zone of inhibition as compared to FLZ reference. The studied microemulsion formulation showed a good stability for a period of 3 months. These results indicate that the studied microemulsion formulation might be a promising vehicle for topical delivery of FLZ.

The purpose of this study was to evaluate the effect of oil, surfactant/co-surfactant mixing ratios and water on the in vitro permeation of ketoconazole (KTZ) applied in O/W microemulsion vehicle through intact rat skin. Lauryl Alcohol (LA) was screened as the oil phase of microemulsions, due to a good solubilizing capacity of the microemulsion system. The pseudo-ternary phase diagrams for microemulsion regions were constructed using LA as the oil, Labrasol (Lab) as the surfactant (S) and ethanol (EtOH) as the cosurfactant (CoS). The formulation which showed a highest permeation rate of 54.65 ± 1.72 µg/cm(2)/h(1) and appropriate physico-chemical properties was optimized as containing 2% KTZ, 10% LA, 20% Lab/EtOH (1:1) and 68% double distilled water (w/w). The efficiency of microemulsion formulation in the topical delivery of KTZ was dependent upon the contents of water and LA as well as Lab/EtOH mixing ratio. It was concluded that the percutaneous absorption of KTZ from microemulsions was enhanced with increasing the LA and water contents, and with decreasing the Lab/EtOH ratio in the formulation. Candida albicans was used as a model fungus to evaluate the antifungal activity of the best formula achieved, which showed the widest zone of inhibition as compared to KTZ reference. The studied microemulsion formulation showed a good stability for a period of three months. Histopathological investigation of rat skin revealed the safety of microemulsion formulations for topical use. These results indicate that the studied microemulsion formulation might be a promising vehicle for topical delivery of KTZ.

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The objective of this study was to develop and evaluate a novel microemulsion based gel formulation containing tazarotene for targeted topical therapy of acne. Psudoternary phase diagrams were constructed to obtain the concentration range of oil, surfactant, and co-surfactant for microemulsion formation. The optimized microemulsion formulation containing 0.05% tazarotene was formulated by spontaneous microemulsification method consisting of 10% Labrafac CC, mixed emulsifiers 15% Labrasol-Cremophor-RH 40 (1:1), 15% Capmul MCM, and 60% distilled water (w/w) as an external phase. All plain and tazarotene-loaded microemulsions were clear and showed physicochemical parameters for desired topical delivery and stability. The permeation profiles of tazarotene through rat skin from optimized microemulsion formulation followed the Higuchi model for controlled permeation. Microemulsion-based gel was prepared by incorporating Carbopol®971P NF in optimized microemulsion formulation having suitable skin permeation rate and skin uptake. Microemulsion-based gel showed desired physicochemical parameters and demonstrated advantage over marketed formulation in improving the skin tolerability of tazarotene indicating its potential in improving its topical delivery. The developed microemulsion-based gel may be a potential drug delivery vehicle for targeted topical delivery of tazarotene in the treatment of acne.

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A new, eco friendly, simple, and rapid high-performance thin-layer chromatographic method was developed and validated for quantitative determination of tazarotene. The HPTLC separation was achieved on an aluminium-backed layer of silica gel 60F 254 using toluene-methanol (9.0 + 1.0 v/v) as mobile phase. Quantitation was achieved by densitometric analysis at 327 nm over the concentration range of 100-500 ng/mL. The method was found to give a compact spot for the drug (R f ¼ 0.75 AE 0.01). The linear regression analysis data for the calibration plots showed a good linear relationship with r 2 ¼ 0.9995. The method was validated for precision, recovery, repeatability, and robustness as per the International Conference on Harmonization guidelines. The minimum detectable amount was found to be 18.59 ng/spot, whereas the limit of quantitation was found to be 56.34 ng/spot. Statistical analysis of the data showed that the method is precise, accurate, reproducible, and selective for the analysis of tazarotene. The method was successfully employed for the estimation of equilibrium solubility, quantification of tazarotene as a bulk drug, in commercially available gel preparation and in-house developed microemulsion based gel formulations.

This study reports the development and evaluation of Carbamazepine (CMP)-loaded microemulsions (CMPME) for intranasal delivery in the treatment of epilepsy. The CMPME was prepared by the spontaneous emulsification method and characterized for physicochemical parameters. All formulations were radiolabeled with 99m Tc (technetium) and biodistribution of CMP in the brain was investigated using Swiss albino rats. Brain scintigraphy imaging in rats was also performed to determine the uptake of the CMP into the brain. CMPME were found crystal clear and stable with average globule size of 34.11 ± 1.41 nm. Tc-labeled CMP solution (CMPS)/CMPME/CMP mucoadhesive microemulsion (CMPMME) were found to be stable and suitable for in vivo studies. Brain/blood ratio at all sampling points up to 8 h following intranasal administration of CMPMME compared to intravenous CMPME was found to be 2-to 3-fold higher signifying larger extent of distribution of the CMP in brain. Drug targeting efficiency and direct drug transport were found to be highest for CMPMME post-intranasal administration compared to intravenous CMP. Rat brain scintigraphy also demonstrated higher intranasal uptake of the CMP into the brain. This investigation demonstrates a prompt and larger extent of transport of CMP into the brain through intranasal CMPMME, which may prove beneficial for treatment of epilepsy.