Comparison of different water/oil microemulsions containing diclofenac sodium: Preparation, characterization, release rate, and skin irritation studies

Abstract

The aim of the present study was to make a comparison of the in vitro release rate of diclofenac sodium (DS) from microemulsion (M) vehicles containing soybean oil, nonionic surfactants (Brij 58 and Span 80), and different alcohols (ethanol [E], isopropyl alcohol [I], and propanol [P]) as cosurfactant. The optimum surfactant:cosurfactant (S:CoS) weight ratios and microemulsion areas were detected by the aid of phase diagrams. Three microemulsion formulations were selected, and their physicochemical properties were examined for the pH, viscosity, and conductivity. According to the release rate of DS, M prepared with P showed the significantly highest flux value (0.059 ± 0.018 mg/cm 2 /h) among all formulations (P G .05). The conductivity results showed that DS-loaded microemulsions have higher conductivity values (18.8-20.2 microsiemens/cm) than unloaded formulations (16.9-17.9 microsiemens/cm), and loading DS into the formulation had no negative effect on system stability. Moreover, viscosity measurements were examined as a function of shear rate, and Newtonian fluid characterization was observed for each microemulsion system. All formulations had appropriate observed pH values varying from 6.70 to 6.85 for topical application. A skin irritation study was performed with microemulsions on human volunteers, and no visible reaction was observed with any of the formulations. In conclusion, M prepared with P may be a more appropriate formulation than the other 2 formulations studied as drug carrier for topical application.

Fabrication, physicochemical characterization and preliminary efficacy evaluation of a W/O/W multiple emulsion loaded with 5% green tea extract

“…However, leakage of internal aqueous phase into the external phase caused thinning of the multiple emulsion samples at higher temperatures. No phase separation occurred and no sudden fall in conductivity values was observed, as it has been reported that too much reduction in conductivity values has been attributed to phase separation (Kantarci et al, 2007).…”

“…The conductivity values of drug loaded emulsions were higher than unloaded formulations and it has been reported previously that conductivity increases in drug loaded formulations (Kantarci et al, 2007). Conductimetric analysis was carried out in order to measure the entrapped conductimetric tracer in the inner aqueous phase of the primary emulsion in order to detect any leakage of internal aqueous phase of the primary emulsion to the outer aqueous phase.…”

Novel isotretinoin microemulsion-based gel for targeted topical therapy of acne: formulation consideration, skin retention and skin irritation studies

“…The unloaded vehicles have a globule size in the range of 22.4-85.9 nm, while drug-loaded vehicles have a globule size in the range of 16.9-72.3 nm. Two explanations, (1) undissolved drug acting as a emulsifier and (2) reduction in emulsifier mobility, are offered in the literature for the decrease in droplet size with the addition of the drug due to deposition of drug particles at the interface of ME (Biruss and Valenta 2008;Djekic and Primorac 2008;Fanun 2008;Kantarci et al 2007). It has been reported that the lowest conductivity plots extend to the largest droplet radius.…”

“…The conductivity results obtained for plain and ITTN-loaded ME formulations (Tables 1 and 2) showed that loading ITTN and the addition of water phase into the formulations had no negative effects on system stability. When an unstable emulsion system and phase separation occurs, the conductivity values are greatly reduced (Kantarci et al 2007). However, the conductivity values for unloaded vehicles were about two to three factors lower than those of ITTN-loaded formulations.…”

“…The viscosity is sensitive to interactions and it is rather an interesting technique to study interactions in systems of known structure. The change in viscosity with the increase in water volume fractions should be correlated to structural effects due to interfacial packing (Biruss and Valenta 2008;Fanun 2008;Kantarci et al 2007). For water content below 10 % w/w, the increase in viscosity indicates increase of volume fraction of dispersed phaseand reflects a transformation of system microstructure due to growth of spherical droplets into larger non-spherical droplets by an attractive interaction as a function of Uw.…”