Enantioselective determination of econazole in rat plasma and its application to a pharmacokinetic study.

Econazole is a widely used chiral antifungal drug. In this paper, an enantioselective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for determination of econazole enantiomers in rat plasma for the first time. After addition of the internal standard (IS) clotrimazole, plasma samples were extracted by liquid-liquid extraction with n-hexane:2-propanol (98.5:1.5, v/v). Baseline separation of the enantiomers was achieved on a Chiralpak® IC column (250 mm × 4.6 mm, 5 µm) using acetonitrile-ammonium acetate buffer (5 mM) (85:15, v/v) as mobile phase. The detection of the analytes was performed in multiple reaction monitoring (MRM) mode with positive electrospray ionization. Transitions of m/z 381.07 â†’ 124.92 and 276.78 â†’ 164.92 were monitored for econazole enantiomers and clotrimazole, respectively. The linear range was 0.20-50.00 ng/mL with the lower limit of quantification of 0.20 ng/mL for both econazole enantiomers in plasma. The intra-day and inter-day precisions were not exceeding 10.2% and the accuracies were within ±15.0%. The validated method was successfully applied to the stereoselective pharmacokinetic study of econazole enantiomers in rat plasma after transdermal administration of racemic econazole nitrate cream. Significant differences were observed in Cmax, AUC and CL/F of econazole enantiomers, indicating the enantioselective pharmacokinetic behavior of econazole in rats.

Phase I Study in Healthy Women of a Novel Antimycotic Vaginal Ovule Combining Econazole and Benzydamine.

Purpose: A novel fixed-dose combination of 150 mg of econazole with 6 mg of benzydamine formulated in vaginal ovules was investigated in a randomised, double-blind, four-parallel group, tolerability, and pharmacokinetic Phase I study in healthy women. Methods: The fixed-dose combination was compared to econazole and benzydamine single-drug formulations and with placebo after daily applications for 3 consecutive days. Safety and tolerability were evaluated recording the adverse drug reactions, local and general tolerability scores, clinical laboratory assays, and vital signs. Econazole, benzydamine, and its metabolite benzydamine N-oxide pharmacokinetics were investigated after single and multiple applications. Results: Local reactions were generally absent. Pruritus and pain at the application site were infrequently reported. According to the subjects' evaluations, the overall tolerability of the ovules was rated as excellent or good. No significant effect of any treatment on laboratory parameters, vital signs, body weight, vaginal pH, or ECG was observed. Very low econazole, benzydamine, and benzydamine-N-oxide concentrations were measured in plasma, though quantifiable in almost all samples. Conclusion: The tested fixed-dose combination showed a good safety profile consistently with the known tolerability of both active substances. In addition, the confirmed low bioavailability of the drugs excludes the possibility of any accumulation effects and limits the risk of undesired systemic effects. This trial is registered at ClinicalTrials.gov with the identifier NCT02720783 last updated on 07 February 2017.

Evaluation of topical econazole nitrate formulations with potential for treating Raynaud's phenomenon.

The purpose of this work was to design and characterize a topical formulation of econazole nitrate (EN) with potential for treating Raynaud's phenomenon (RP). Four topical dosage forms (F1_topical solution, F2_HPMC or hydroxypropyl methylcellulose dispersion, F3_VersaBase® cream, and F4_Lipoderm® Activemax™ Cream) containing 3% w/w EN were prepared and characterized for drug content, pH, viscosity, spreadability, drug crystallinity, stability, and in vitro permeation using Franz cells across pig ear skin, and results were compared to the 1% marketed EN cream. All four formulations had acceptable physical and visual characteristics required for topical application, with 3% w/w EN. The order of amount of drug permeated from highest to lowest was F2 (10.27%) > F4 (2.47%) > F1 (2.28%) > F3 (1.47%) > marketed formulation (0.22%). Formulation F2 showed better penetration of the drug into the stratum corneum, epidermis, and dermis layers. The drug concentration in the stratum corneum and epidermis was approximately 10-20 times higher with F2 compared to the marketed formulation. All formulations were found to be stable for up to 6 months. All four EN formulations were found to be better than the 1% marketed cream. Formulation F2_HPMC dispersion could be further explored as a treatment option for RP.

Ophthalmic Econazole Hydrogels for the Treatment of Fungal Keratitis.

Econazole is a feasible alternative treatment in the management of fungal keratitis. Nevertheless, its low water solubility is considered the main limitation to the incorporation into ophthalmic formulations. In this work, econazole nitrate is solubilized by using cyclodextrins to achieve an optimum therapeutic concentration. Phase solubility diagrams suggest α-cyclodextrin as the most effective cyclodextrin and later the inclusion complex formed with this one was characterized in solution by 1D, 2D-NMR, and molecular modeling. Econazole-α-cyclodextrin inclusion complex was included in 2 types of ocular hydrogels: a natural polysaccharides ion-sensitive hydrogel and a hyaluronic acid hydrogel. Both of them show no ocular irritation in the hen's egg test on chorioallantoic membrane assay and a controlled econazole release over time. Permeability studies suggest that hydrogels do not modify the econazole nitrate permeability through bovine cornea in comparison with an econazole-α-cyclodextrin inclusion complex solution. Finally, ocular biopermanence studies performed using positron emission tomography show these hydrogels present a high retention time on the eye. Results suggest the developed formulations have a high potential as vehicles for the econazole topical ocular administration as fungal keratitis treatment.

Bioequivalence Methodologies for Topical Drug Products: In Vitro and Ex Vivo Studies with a Corticosteroid and an Anti-Fungal Drug.

OBJECTIVE: To examine whether in vitro and ex vivo measurements of topical drug product performance correlate with in vivo outcomes, such that more efficient experimental approaches can be reliably and reproducibly used to establish (in)equivalence between formulations for skin application. MATERIALS AND METHODS: In vitro drug release through artificial membranes, and drug penetration into porcine skin ex vivo, were compared with published human in vivo studies. Two betamethasone valerate (BMV) formulations, and three marketed econazole nitrate (EN) creams were assessed. RESULTS: For BMV, the stratum corneum (SC) uptake of drug in 6 h closely matched data observed in vivo in humans, and distinguished between inequivalent formulations. SC uptake of EN from the 3 creams mirrored the in vivo equivalence in man (both clinically and via similar tape-stripping experiments). However, EN clearance from SC ex vivo did not parallel that in vivo, presumably due to the absence of a functioning microcirculation. In vitro release of BMV from the different formulations did not overlap with either ex vivo or in vivo tape-stripping data whereas, for EN, a good correlation was observed. No measurable permeation of either BMV or EN was detected in a 6-h in vitro skin penetration experiment. CONCLUSIONS: In vitro and ex vivo methods for topical bioequivalence determination can show correlation with in vivo outcomes. However, these surrogates have understandable limitations. A "one-size-fits-all" approach for topical bioequivalence evaluation may not always be successful, therefore, and the judicious use of complementary methods may prove a more effective and reliable strategy.

Skin permeation of econazole nitrate formulated in an enhanced hydrophilic multiple emulsion.

Local delivery of imidazolic antifungals is limited by its extreme lipophilicity. Multiple emulsions (ME) are a potential vehicle to enhance the delivery of econazole nitrate (ECN), an antifungal targeted to deep-seated epidermal yeast infections. An 1% ECN hydrophilic ME was compared with a commercial formulation in terms of rheology, droplet size and in vitro antifungal activity against Candida species. Comparative in vitro drug release, human skin permeation and drug retention were investigated using vertical diffusion cells. Rheology demonstrated a pseudoplastic shear thinning with thixotropy facilitating skin residence. No significant aggregation or droplet size variations were observed during a 6-month stability storage. Both formulations exhibited similar release levels achieving asymptotic values in 5 h. ECN skin permeation levels from the multiple emulsion resulted to be significantly higher than those of the commercial formulation, attributable to differences in formulation polarity and excipients composition. Conversely, similar drug accumulation levels in skin were obtained (40-130 ppm). These concentrations resulted to be comparable with obtained MIC values (2-78 ppm), confirming the in vitro antimicrobial efficacy of both formulations. A similar skin retention and a higher permeation rate over the existing formulations is considered an improved approach to target the drug to deep epidermis.

Nano Spray Drying Technique as a Novel Approach To Formulate Stable Econazole Nitrate Nanosuspension Formulations for Ocular Use.

The effect of using methyl-ß-cyclodextrin and hydroxypropyl-ß-cyclodextrin as carriers for econazole nitrate nanoparticles prepared by nano spray dryer was explored in this work. Stabilizers, namely, poly(ethylene oxide), polyvinylpyrrolidone k30, poloxamer 407, Tween 80, and Cremophor EL, were used. The nano spray dried formulations revealed almost spherical particles with an average particle size values ranging from 121 to 1565 nm and zeta potential values ranging from -0.8 to -2.5 mV. The yield values for the obtained formulations reached 80%. The presence of the drug in the amorphous state within the nanosuspension matrix system significantly improved drug release compared to that for pure drug. Combination of hydroxypropyl-ß-cyclodextrin with Tween 80 achieved an important role for preserving the econazole nanosuspension from aggregation during storage for one year at room temperature as well as improving drug release from the nanosuspension. This selected formulation was suspended in chitosan HCl to increase drug release and bioavailability. The in vivo evaluation on albino rabbit's eyes demonstrated distinctly superior bioavailability of the selected formulation suspended in chitosan compared to its counterpart formulation suspended in buffer and crude drug suspension due to its mucoadhesive properties and nanosize. The nano spray dryer could serve as a one step technique toward formulating stable and effective nanosuspensions.

Novel drug delivery strategies for improving econazole antifungal action.

Econazole is a commonly used azole antifungal in clinical treatment of superficial fungal infections. It is generally used as conventional cream and gel preparations under the brand names of Spectazole (United States), Ecostatin (Canada), Pevaryl (Western Europe). Treatment efficiency of antifungal drugs depends on their penetration through target layers of skin at effective concentrations. Econazole's poor water solubility limits its bioavailability and antifungal effects. Therefore, formulation strategies have been examined for delivering econazole through targeted skin sites. The present overview focuses on novel nano-based formulation approaches used to improve econazole penetration through skin for treatment of superficial fungal infections.

A luminescent ruthenium(II) complex for light-triggered drug release and live cell imaging.

We report a novel ruthenium(II) complex for selective release of the imidazole-based drug econazole. While the complex is highly stable and luminescent in the dark, irradiation with green light induces release of one of the econazole ligands, which is accompanied by a turn-off luminescence response and up to a 34-fold increase in cytotoxicity towards tumour cells.

Ocular supersaturated self-nanoemulsifying drug delivery systems (S-SNEDDS) to enhance econazole nitrate bioavailability.

Econazole nitrate (ECO) is a poorly water soluble antifungal drug. Having low aqueous solubility affects negatively its use for ocular treatment. This work aimed to prepare ocular supersaturated self-nanoemulsifying drug delivery systems (S-SNEDDS) of ECO employing hydroxypropyl methylcellulose as a precipitation inhibitor to improve the drug solubility by avoiding its precipitation after administration. Various oils, surfactants and co-surfactants were used to construct SNEDDS. The SNEDDS were evaluated for globule size, polydispersity index and their irritation potential using hen's egg test-chorioallantoic membrane (HET-CAM). The best SNEDDS was loaded with ECO and HPMC to prepare S-SNEDDS. In-vitro precipitation test of the S-SNEDDS was done to study the effect of the precipitation inhibitor. ECO permeation in rabbits' eyes from the selected S-SNEDDS (with and without HPMC) was evaluated. The results showed that SNEDDS-X consisting of 20% Capmul(®) MCM C10 as an oil, 60% Cremophor RH40(®) as a surfactant and 20% Transcutol(®) HP as co-surfactant possessed the lowest PDI value and a non-irritant effect on the CAM. The in-vitro precipitation test showed that the use of HPMC successfully sustained the supersaturated state by avoiding ECO precipitation. Higher Cmax, AUC0-8 and longer tmax confirm the development of a successful ECO-loaded S-SNEDDS.

Development of thermodynamically stable nanostructured lipid carrier system using central composite design for zero order permeation of econazole nitrate through epidermis.

The investigation was aimed at developing thermodynamically stable topical delivery system of nanostructured lipid carrier of econazole nitrate (EN) for the treatment of deep seated fungal infection by improving its permeability. Fifteen formulations (F1-F15) of nanostructured lipid carriers (NLCs) were prepared by solvent injection technique using central composite design and characterized for particle size and % entrapment efficiency. Closeness in the results, guided the selection of five NLC formulations which were formulated as hydrogels (G1-G5) using Carbopol 934. The permeation studies of gels demonstrated G3 with flux rate of 3.21 ± 0.03 µg/cm(2)/min (> target flux of 1.46 µg/cm(2)/min) as the best formulation that exhibited zero order permeation. The amount of drug/unit area demonstrated linear dependency on flux rate. Confocal laser scanning microscopy demonstrated penetration of rhodamine red till the stratum basale due to hydration of stratum corneum. Hydrogel G3 containing NLC formulation (F5) was selected as the optimized topical gel. TEM of F5 revealed spherical particles that presented low recrystallization index of 72.35%. Stability profile for 90 days revealed insignificant change (p < 0.05) in the particle size and zeta potential indicating substantial stability of the system. Thus, EN-loaded NLC indicated better permeability and thermodynamic stability as effective topical delivery system for deep seated fungal infection.

Nanosized ethanolic vesicles loaded with econazole nitrate for the treatment of deep fungal infections through topical gel formulation.

This project aimed at developing nanovesicles of econazole nitrate (EN) and formulating them as a suitable dermatological gel for improved therapeutic efficacy, better dispersity, and good storage stability. Ethosomes were prepared by cold method and evaluated for the mean diameter, surface charge, and entrapment efficiency. Optimized ethosomes with vesicle size and entrapment efficiency of 202.85 ± 5.10 nm and 81.05 ± 0.13%, respectively, were formulated as Carbopol 934 NF gels with varied permeation enhancers (G1-G7), and compared with liposomal and hydroethanolic gels. The pharmacotechnical evaluation of gels demonstrated G6 with a flux rate of 0.46 ± 0.22 µg/cm(2) hr(1/2) as the best formulation that was able to exhibit controlled release of EN for 12 hours across rat skin, and percent drug diffused from ethosomes was nearly twofold higher than liposomal and hydroethanolic gels. Confocal laser scanning microscopy demonstrated drug permeation as far as the last layer of epidermis (stratum basale). Stability profile of the prepared system assessed for 180 days revealed very low aggregation and insignificant growth in vesicular size. The results collectively suggest that because of the controlled drug release, better antifungal activity, and good storage stability, EN ethosomal gel has tremendous potential to serve as a topical delivery system. FROM THE CLINICAL EDITOR: Ethosomal gel of econazole nitrate was found to have outstanding potential to serve as a topical delivery system, enabling controlled drug release, providing better antifungal activity, and good storage stability.

Polymeric nanosponges as an alternative carrier for improved retention of econazole nitrate onto the skin through topical hydrogel formulation.

The present study was carried out to exploit the feasibility of using polymeric nanosponges as an alternative carrier for targeting econazole nitrate (EN) to the skin through topical hydrogel formulation. Nanosponges prepared by emulsion solvent diffusion method were evaluated for various physicochemical parameters and in vitro drug release. The nanosponges of EN were discrete free flowing nanosized particles with perforated orange peel like morphology as visualized by SEM. The nanosponge formulated using PVA:EC (3:2) displayed highest in vitro release after 12?h in phosphate buffer (pH 6.8) that fitted matrix model. Selected nanosponge was formulated as Carbopol 934 NF hydrogel using varying concentrations of permeation enhancers propylene glycol and N-methyl-2-pyrrolidone. The EN nanosponge-loaded hydrogels (F0?F7) were evaluated for pharmacotechnical properties and irritation studies on rat skin. On the basis of various evaluation parameters F7 with an equilibrium swelling of 0.944?g/g after 4?h, low firmness and high adhesiveness, a flux rate of 1540.2 (?g/cm(2).h) and that exhibited a controlled release of EN for 12?h was selected as best hydrogel. The DRS and DSC spectra of F7 confirmed stability of drug in the delivery system and absence of drug polymer interaction in nanosponges.

Evaluation of solid lipid microparticles produced by spray congealing for topical application of econazole nitrate.

OBJECTIVES: The aims of this study were to evaluate the suitability of the spray congealing technique to produce solid lipid microparticles (SLMs) for topical administration and to study the skin permeation of a drug from SLMs compared with solid lipid nanoparticles (SLNs). METHODS: Econazole nitrate was used as model drug and Precirol ATO 5 as the lipidic carrier. SLMs and SLNs were both prepared at 5:1, 10:1 and 12.5:1 lipid:drug weight ratios and characterised in terms of particle size, morphology, encapsulation efficiency and chemical analysis of the particle surface. SLMs and SLNs were also incorporated into HPMC K 100M hydrogels for ex-vivo drug permeation tests using porcine epidermis. KEY FINDINGS: SLMs had particle sizes of 18-45 microm, while SLNs showed a mean diameter of 130-270 nm. The encapsulation efficiency was 80-100%. Permeation profiles of econazole nitrate were influenced by both particle size (significant difference until 9 h) and the amount of lipid. CONCLUSIONS: The results confirm the usefulness of SLNs as carriers for topical administration and suggest the potential of SLMs for the delivery of drugs to the skin.

Solid lipid nanoparticles (SLN) as carriers for the topical delivery of econazole nitrate: in-vitro characterization, ex-vivo and in-vivo studies.

Solid lipid nanoparticles (SLN) designed for topical administration of econazole nitrate (ECN), were prepared by o/w high-shear homogenization method using different ratios of lipid and drug (5:1 and 10:1). SLN were characterized in terms of particle size, morphology, encapsulation efficiency and crystalline structure. After incorporation of SLN into hydrogels, rheological measurements were performed, and ex-vivo drug permeation tests were carried out using porcine stratum corneum (SC). In-vivo study of percutaneous absorption of ECN as a function of application time and composition of gels was carried out by tape-stripping technique. Penetration tests of the drug from a conventional gel were performed as comparison. High-shear homogenization method resulted in a good technique for preparation of ECN-loaded SLN. Particles had a mean diameter of about 150 nm and a regular shape and smooth surface. The encapsulation efficiency values were about 100%. Ex-vivo tests showed that SLN were able to control the drug release through the SC; the release rate depended upon the lipid content on the nanoparticles. In-vivo studies demonstrated that SLN promoted a rapid penetration of ECN through the SC after 1 h and improved the diffusion of the drug in the deeper skin layers after 3 h of application compared with the reference gel.

Near infrared spectrometry for the quantification of human dermal absorption of econazole nitrate and estradiol.

PURPOSE: The purpose of this study was to demonstrate the use of near-infrared (NIR) spectrometry for the in vitro quantification of econazole nitrate (EN) and estradiol (EST) in human skin. METHODS: NIR spectra were collected from EN and EST powders to verify the presence of NIR chromophores. One percent EN cream, a saturated solution of EN, or 0.25% EST solution was applied to human skin. NIR spectra were collected and one-point net analyte signal (NAS) multivariate calibration was used to predict the drug concentrations. NIR results were validated against known skin concentrations measured by high-pressure liquid chromatography (HPLC) analysis of solvent extracts. RESULTS: NIR spectroscopy measured dermal absorption from saturated solutions of EN on human skin with an r2=0.990, standard error of estimation (SEE)=2.46%, and a standard error of performance (SEP)=3.55%, EN cream on skin with an r2=0.987, SEE=2.30%, and SEP=2.66%, and 0.25% solutions of EST on skin with an r2=0.987, SEE=3.30%, and SEP=5.66%. Despite low permeation amounts of both drugs through the stratum corneum into human tissue, the NIR signal-to-noise ratio was greater than three, even for the lowest concentrations. CONCLUSION: NIR analyses paralleled the results obtained from HPLC, and thus could serve as a viable alternative for measuring the topical bioavailability/bioequivalence of different EN and EST formulations. Because these experiments were conducted in human tissue, this research suggests an all-optical in vivo method of measurement for dermal absorption could be developed.

A parenteral econazole formulation using a novel micelle-to-liposome transfer method: in vitro characterization and tumor growth delay in a breast cancer xenograft model.

PURPOSE: The purpose of this study was to develop a parenteral liposomal formulation of econazole, a poorly water-soluble compound not previously available in an intravenous form. We are investigating econazole as an anticancer agent based on its unique mechanism of action to which cancer cells are preferentially sensitive. An intravenous formulation of econazole was desired for preclinical toxicity and efficacy studies of econazole. METHODS: Liposomal econazole was prepared using a novel micelle exchange technique to incorporate the drug into the lipid bilayer of pre-formed liposomes using a poly(ethylene) glycol-linked phospholipid, distearoyl phosphatidylethanolamine (DSPE-PEG). This method allowed for stable and efficient drug incorporation into DPPC and DMPC liposomes at a final drug:lipid ratio of 0.05 (w/w) and increased solubility in saline from <0.1 to 5 mg/ml. RESULTS: Stability over 14 days at 4 degrees C in buffer was demonstrated as well as in vitro plasma stability at 37 degrees C. Plasma elimination studies of micelle-loaded liposomal econazole showed a half-life of approximately 35 min and plasma AUC of 281 microg/ml min. In MCF-7 human breast cancer xenografts in Rag2M mice. Liposomal econazole did not induce significant hepatoxicity, renal toxity or weight loss compared to empty liposomes. Tumor growth was slightly delayed in liposomal econazole-treated mice, with approximately 10-day lag time to reach 300 mm(3) compared to vehicle controls. CONCLUSIONS: The micelle transfer method provided an efficient means of preparing liposomal econazole suitable for intravenous administration. Liposomal econazole was successfully administered to tumor bearing mice at 50 mg/kg, and no significant toxicities attributable to econazole were observed.

Azole antifungals as novel chemotherapeutic agents against murine tuberculosis.

The present study was designed to evaluate the in vivo antimycobacterial potential of econazole alone and in combination with antitubercular drugs against tuberculosis in mice. Econazole was found to reduce bacterial burden by 90% in the lungs and spleen of mice infected with 1 x 10(7) cells of Mycobacterium tuberculosis and was found to be equipotent to rifampicin. Further, our results indicate that econazole can replace rifampicin/isoniazid as well as both rifampicin and isoniazid in chemotherapy of murine tuberculosis. Econazole alone or in combination with antitubercular drugs did not produce any hepatotoxicity in normal or M. tuberculosis-infected mice.

Near-infrared spectrometry for the quantification of dermal absorption of econazole nitrate and 4-cyanophenol.

PURPOSE: The purpose of this study was to demonstrate the utility of near-infrared (NIR) spectroscopy for the in vitro quantification of econazole nitrate (EN) and 4-cyanophenol (4-CP) in hairless guinea pig skin. METHODS: NIR spectra were collected from each of the following: EN and 4-CP powders, EN and 4-CP in solution, and skin samples following topical exposure to either 4-CP in water or EN in propylene glycol and topical creams. To predict drug concentration from NIR spectra, principal component regression (PCR), interval PCR, and uninformative variable elimination PCR were each used with a leave-one-out cross-validation, and results were compared. NIR results were validated against known skin concentrations measured by high-pressure liquid chromatography (HPLC) analysis of solvent extracts. RESULTS: NIR results matched the HPLC results for the quantification of 4-CP and EN in skin exposed to saturated solutions and topical creams with an r2 > 0.90, a standard error of estimation < 7.0%, and a standard error of performance < 8.0%. CONCLUSION: This experiment demonstrated that NIR closely parallels results obtained from tissue extraction and HPLC analysis, proving its potential utility for the rapid and noninvasive determination of topical bioavailability/bioequivalence of EN and quantification of the model chemical 4-CP. Investigation of drugs in human skin is now justified.