Microemulsion-based hydrogel formulation of ibuprofen for topical delivery

The purpose of this study was to construct microemulsion-base hydrogel formulation for topical delivery of ibuprofen. Ethyl oleate (EO) was screened as the oil phase of microemulsions, due to a good solubilizing capacity of the microemulison systems and excellent skin permeation rate of ibuprofen. The pseudo-ternary phase diagrams for microemulsion regions were constructed using ethyl oleate as the oil, Tween 80 as the surfactant, propylene glycol as the cosurfactant. Various microemulsion formulations were prepared and the abilities of various microemulsions to deliver ibuprofen through the skin were evaluated in vitro using Franz diffusion cells fitted with porcine skins. The in vitro permeation data showed that microemulsions increased the permeation rate of ibuprofen 5.72-30.0 times over the saturated solution. The optimum formulation consisted of 3% ibuprofen, 6% EO, 30% Tween 80/PG (2:1) and water, showed a high permeation rate of 38.06 microg cm(-2) h(-1). Xanthan gum as a gel matrix was used to construct the microemulsion-based hydrogel for improving the viscosity of microemulsion for topical administration. The studied microemulsion-based hydrogel showed a good stability. These results indicate that the studied microemulsion-based hydrogel may be a promising vehicle for topical delivery of ibuprofen.     

Hydrogel-thickened nanoemulsion system for topical delivery of lipophilic drugs

In this work, a hydrogel-thickened nanoemulsion system (HTN) with powerful permeation ability, good stability and suitable viscosity was investigated for topical delivery of active molecules. HTN was prepared to deliver an oily mixture of 5% camphor, 5% menthol and 5% methyl salicylate for topical therapy of arthritis, minor joint and muscle pain using soybean oil as the oil phase, soybean lecithin, Tween 80 and poloxamer 407 as the surfactants, propylene glycol as the cosurfactant, carbomer 940 as a thickening agent. The HTN system was found to combine the o/w microstructure of nanoemulsion with the gel network of hydrogel and had a suitable viscosity of 133.2PaS. The system had small average diameters and good long-term stability. The abilities of HTN to deliver the high amounts of camphor, menthol and methyl salicylate were evaluated using the in vitro permeation studies. The permeation rates of camphor, menthol and methyl salicylate from the optimal HTN formulation were 138.0+/-6.5, 63.6+/-3.3, 53.8+/-3.2 microg cm(-2) h(-1) and showed the significant advantages over the control gel. The HTN with good stability and powerful permeation enhancing ability and suitable viscosity might be a promising prospective carrier for topical delivery of lipophilic drugs.     

Deformable liposomes and ethosomes as carriers for skin delivery of ketotifen

Deformable liposomes and ethosomes were investigated as carriers for skin delivery of ketotifen (KT) in terms of vesicle size, entrapment efficiency, stability, in vitro permeation and skin deposition properties. Phosphatidylcholine (PC) from soybean lecithin was used in the preparation of all vesicles. Sodium cholate, sodium deoxycholate and Tween 80 were investigated as edge activators in preparation of KT deformable liposomes. KT ethosomes were prepared in two PC concentrations, 2% and 4.25% w/v, in 30% v/v ethanol. KT deformable liposomes showed improved entrapment efficiency over KT ethosomes. KT deformable liposomes with Tween 80 as an edge activator were more stable upon storage at 5 +/- 1 degree C than those prepared using sodium cholate or sodium deoxycholate and were more stable than KT ethosomes. In vitro permeation and skin deposition studies employed only deformable liposomes with Tween 80 as an edge activator and ethosomes with 4.25% w/v PC concentration. Both of them improved skin delivery of KT over controls and over traditional liposomes, with greater improvement of KT skin deposition than KT skin permeation, hence are more useful for dermal than for transdermal delivery of KT.     

Topical ketoprofen nanogel: artificial neural network optimization,clustered bootstrap validation,and in vivo activity evaluation based on longitudinal dose response modeling

Objectives: This work aimed at investigating the potential of solid lipid nanoparticles (SLN) as carriers for topical delivery of Ketoprofen (KP); evaluating a novel technique incorporating Artificial Neural Network (ANN) and clustered bootstrap for optimization of KP-loaded SLN (KP-SLN); and demonstrating a longitudinal dose response (LDR) modeling-based approach to compare the activity of topical non-steroidal anti-inflammatory drug formulations.

Methods: KP-SLN was fabricated by a modified emulsion/solvent evaporation method. Box–Behnken design was implemented to study the influence of glycerylpalmitostearate-to-KP ratio, Tween 80, and lecithin concentrations on particle size, entrapment efficiency, and amount of drug permeated through rat skin in 24?hours. Following clustered bootstrap ANN optimization, the optimized KP-SLN was incorporated into an aqueous gel and evaluated for rheology, in vitro release, permeability, skin irritation and in vivo activity using carrageenan-induced rat paw edema model and LDR mathematical model to analyze the time course of anti-inflammatory effect at various application durations.

Results: Lipid-to-drug ratio of 7.85 [bootstrap 95%CI: 7.63–8.51], Tween 80 of 1.27% [bootstrap 95%CI: 0.601–2.40%], and Lecithin of 0.263% [bootstrap 95%CI: 0.263–0.328%] were predicted to produce optimal characteristics. Compared with profenid® gel, the optimized KP-SLN gel exhibited slower release, faster permeability, better texture properties, greater efficacy, and similar potency.

Conclusions: SLNs are safe and effective permeation enhancers. ANN coupled with clustered bootstrap is a useful method for finding optimal solutions and estimating uncertainty associated with them. LDR models allow mechanistic understanding of comparative in vivo performances of different topical formulations, and help design efficient dermatological bioequivalence assessment methods.     

Cyclosporine A loaded SLNs: evaluation of cellular uptake and corneal cytotoxicity

Cyclosporine A (CsA) loaded solid lipid nanoparticles (SLNs) for topical ophthalmic applications were prepared by high shear homogenization and ultrasound method using Compritol 888 ATO, Poloxamer 188 and Tween 80, to investigate the cellular uptake of rabbit corneal epithelial cells (RCE) and to evaluate the cytotoxicity. The size of the optimized formulation was 225.9+/-5.5 nm with a polydispersity index of 0.253+/-0.05. The zeta potential and entrapment efficiency was detected as -16.9+/-0.7 mV and 95.6%, respectively. The CsA release was found to be enzyme (lipase/co-lipase complex) dependent. SLNs were sterilized at 110 and 121 degrees C. The cytotoxicity was evaluated in vitro by means of RCE cells and was higher at 121 degrees C sterilization temperature, probably due to a supposed leakage of Tween 80 following lipid re-crystallization. The permeation and penetration of CsA across/into the corneal cells were evaluated using in vitro and ex vivo experiments. The cellular uptake was investigated by replacing CsA with the fluorescent dye Rhodamine B. The penetration enhancement properties were supported by confocal laser scanning microscopy analysis. The internalization of SLNs in cornea and in RCE cell lines was confirmed, pointing out the possibility of CsA targeting to the cornea.     

Solid lipid nanoparticle and microemulsion for topical delivery of triptolide.

Triptolide (TP) has been shown to have anti-inflammatory, immunosuppressive, anti-fertility and anti-neoplastic activities. However, its clinical use is restricted to some content due to its poor water solubility and some toxic effects. In order to find innovative ways for administering TP and alleviating its disadvantages, the controlled release delivery systems such as solid lipid nanoparticle (SLN) and microemulsion have been developed. In the present paper we describe the preparation and some characterization of specialized delivery systems for TP. The transdermal delivery capacity and anti-inflammatory activity were also evaluated. The results indicated that these SLN dispersions and microemulsions could serve as efficient promoters for the TP penetrating into skin. Furthermore, different formulations were optimized in this study. The best formulation of SLN dispersion consisted of 5% tristearin glyceride, 1.20% soybean lecithin and 3.60% polyethylene glycol (400) monosterate, while the best formulation of microemulsion consisted of 40% isopropyl myristate, 50% Tween-80: 1,2-propylene glycol (5:1, v/v) and water. The steady-state flux (Js) and permeability coefficient (Kp) of triptolide for the SLN dispersion of the first 6 h were 3.1+/-0.4 microg/cm2 per h and 0.0124+/-0.001 cm/h or 6.4+/-0.7 microg/cm2 per h and 0.0256+/-0.002 cm/h for the microemulsion, which was 3.45 and 7.02 times higher than those of triptolide solution, respectively. The anti-inflammatory activity of SLN dispersion was stronger than that of microemulsion in carrageenan induced rat paw edema. However, the results were the reverse in complete Frenud's adjuvant induced paw edema. Further investigations should be carried out on the toxicity of different formulations of triptolide to tissues.     

Comparative study of liposomes,transfersomes and ethosomes as carriers for improving topical delivery of celecoxib

Topical administration of celecoxib proved to be an effective mean of preventing skin cancer development and improving anticancer drugs effectiveness in skin tumors treatment. The aim of this study was the development of an effective topical formulation of celecoxib, able to promote drug skin delivery, providing its in depth penetration through the skin layers. Three kinds of vesicular formulations have been investigated as drug carriers: liposomes containing a surfactant, or transfersomes and ethosomes, containing suitable edge activators. Firstly, the effect of membrane composition variations on the system performance has been evaluated for each vesicle type. Selected formulations were characterized for particle size, polydispersity index and encapsulation efficiency. The best formulations were subjected to ex vivo permeation studies through excised human skin. All vesicular formulations markedly (p < 0.001) improved the drug amount penetrated into the skin with respect to an aqueous suspension, from 2.0 to 6.5, up to 9.0 folds for liposomes, transfersomes and ethosomes, respectively. In particular, ethosomes containing Tween 20 as edge activator not only showed the best vesicle dimensions and homogeneity, and the highest encapsulation efficacy (54.4%), but also enabled the highest increase in drug penetration through the skin, probably due to the simultaneous presence in their composition of ethanol and Tween 20, both acting as permeation enhancers. Therefore, among the various vesicular formulations examined in the study, Tween 20-ethosomes can be considered the most promising one as carrier for topical celecoxib applications aimed to prevent skin cancer development and increase the anticancer drugs effectiveness against skin tumors.     

Effect of penetration enhancers on in vitro percutaneous penetration of nimesulide through rat skin

The influence of several penetration enhancers alone and/or in various combinations on the percutaneous penetration of nimesulide (NM) from Carbopol 934 based gel formulations was investigated. Skin permeation studies were performed using Franz-type diffusion cells and full-thickness abdominal rat skin. Various types of compounds such as ethanol, isopropyl alcohol, propylene glycol, Transcutol, Tween 80 and oleic acid were employed as penetration enhancers. The steady-state flux, the lag time and permeability coefficients of NM for each formulation were calculated. The results showed that the skin permeability of NM from gels tested was significantly increased (P < 0.05) by isopropyl alcohol (40%) and the combination of oleic acid (3%) with Transcutol (30%) when compared with the control formulation. In conclusion, these substances could be considered as penetration enhancers for NM topical formulations.     

Liposomes and niosomes as potential carriers for dermal delivery of minoxidil

The aim of this work was to formulate minoxidil loaded liposome and niosome formulations to improve skin drug delivery. Multilamellar liposomes were prepared using soy phosphatidylcholine at different purity degrees (Phospholipon 90, 90% purity, soy lecithin (SL), 75% purity) and cholesterol (Chol), whereas niosomes were made with two different commercial mixtures of alkylpolyglucoside (APG) surfactants (Oramix NS10, Oramix CG110), Chol and dicetylphosphate. Minoxidil skin penetration and permeation experiments were performed in vitro using vertical diffusion Franz cells and human skin treated with either drug vesicular systems or propylene glycol-water-ethanol solution (control). Penetration of minoxidil in epidermal and dermal layers was greater with liposomes than with niosomal formulations and the control solution. These differences might be attributed to the smaller size and the greater potential targeting to skin and skin appendages of liposomal carriers, which enhanced globally the skin drug delivery. The greatest skin accumulation was always obtained with non-dialysed vesicular formulations. No permeation of minoxidil through the whole skin thickness was detected in the present study irrespective of the existence of hair follicles. Alcohol-free liposomal formulations would constitute a promising approach for the topical delivery of minoxidil in hair loss treatment.     

Novel microemulsion-based gel formulation of tazarotene for therapy of acne

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.