Development and Validation of HPLC Method for Efinaconazole: Application to Human Nail Permeation Studies.

Efinaconazole is the first azole derivative approved by FDA for the topical treatment of onychomycosis. The objective of present study was to develop and validate HPLC method for estimation of efinaconazole in ex vivo human nail permeation study samples. The chromatographic analysis was performed on a HPLC system equipped with diode array detector. The efinaconazole and internal standard (IS) were extracted from the human nail samples by using the protein precipitation method. The samples were injected on to 5 µm Polar C18 100Å, 4.6 mm × 150 mm column. The mobile phase consisted of 0.01 M potassium dihydrogen phosphate: acetonitrile (36:64) and eluent was monitored at 205 nm. The chromatographic separation of drug and analyte was achieved using isocratic elution at flow rate of 1 mL/min with a total run time of 15 min. The efinaconazole and IS were eluted at 6.4 ± 0.5 and 8.3 ± 0.5 min, respectively. The developed method was validated as per FDA guidelines, and the results met with acceptance criteria. The method developed was specific, and the analyte concentrations were linear at range of 50 to 10000 ng/mL (R2 ≥ 0.9981). The validated HPLC method was applied for quantifying efinaconazole in human nail permeation study samples. The permeation of efinaconazole was increased by twofolds with Labarfac CC (15135.4 ± 2233.9 ng/cm2) compared to formulations containing Transcutol P (6892.0 ± 557.6 ng/cm2) and Labrasol (7266.1 ± 790.6 ng/cm2). The study results demonstrate that developed efinaconazole HPLC method can be employed for formulation evaluation and clinical studies.

Development by design of experiment and validation of a HPLC-UV method for simultaneous quantification of 1-nitro-2-phenylethane and methyleugenol: Application to nail permeation/retention studies.

Aniba canelilla (Kunth) Mez is an aromatic tree from Amazon region whose essential oil presents 1-nitro-2-phenylethane (NP) and methyleugenol (ME) as major compounds. Several properties are attributed to Aniba canelilla essential oil (ACEO), such as antifungal. Onychomycoses are fungal nail infections that require novel therapeutic alternatives, especially topical ones. However, to ensure the success of topical therapy, the active compound should be able to penetrate/permeate the nail plate, which is challenging due to the highly keratinized composition of this structure. Thus, the aims of this article were to develop, validate and apply a high-performance liquid chromatography method (HPLC-UV) to quantify NP and ME in porcine hoof extract (PHE) and receptor fluid (RF) during in vitro permeation/retention studies in nail model, for which porcine hoof membranes were used. For method development, two Designs of Experiment (DoE) were adopted: 23 Full Factorial and Box-Behnken. Retention times of 5.65 and 7.49 min were achieved for NP and ME, respectively. The method was full validated for NP and ME quantification in receptor fluid, in accordance with the recommended parameters by ICH Q2(R1) Guideline. In addition, the method was full validated for NP and ME quantification in porcine hoof extract, considering the parameters and criteria of ICH M10 Guideline. In vitro permeation/retention studies were carried out in nail model, and promising results were obtained. NP reached the receptor fluid in the order of 441.1 ± 92.1 µg/cm2 at 72 h. The amount of NP and ME retained into porcine hoof membrane was 1272.6 ± 225.7 µg/cm2 and 84.7 ± 20.4 µg/cm2, respectively, at 72 h. Our findings open perspective to develop topical formulations containing ACEO as active compound aiming the management of onychomycosis.

Poly(pseudo)rotaxanes formed by mixed micelles and α-cyclodextrin enhance terbinafine nail permeation to deeper layers.

This work aimed to develop water-based formulations for onychomycosis topical treatment using micelles of small pegylated surfactants associated with α-cyclodextrin (αCD) to deliver terbinafine to the nail. Kolliphor® RH40 (RH40) and Gelucire® 48/16 (GEL) single and mixed micelles (RH40:GEL 1:1) were prepared. αCD was added to the surfactants dispersions to form poly(pseudo)rotaxanes (PPR). Formulations were characterized in terms of drug solubilization (3 to 34-fold increase), particle size (9-11 nm) and Z-potential (+0.3 - +1.96 mV), blood compatibility (non-hemolytic), rheological behavior (solid-like viscoelastic properties after 5-10% αCD addition), drug release and interaction with the nail plate. GEL micelles and surfactant-10% αCD PPRs notably hydrated the nail plate. The high viscosity of PPR led to a slower drug release, except for RH40:GEL +10% αCD that surprisingly released terbinafine faster. The RH40:GEL +10% αCD formulation delivered twice more amount of terbinafine to deeper regions of nail plate compared to other formulations. The results evidenced the potential of PPR formed by small pegylated surfactants as a water-based formulation for nail drug delivery.

Constant Voltage Iontophoresis Technique to Deliver Terbinafine via Transungual Delivery System: Formulation Optimization Using Box-Behnken Design and In Vitro Evaluation.

Topical therapy of antifungals is primarily restricted due to the low innate transport of drugs through the thick multi-layered keratinized nail plate. The objective of this investigation was to develop a gel formulation, and to optimize and evaluate the transungual delivery of terbinafine using the constant voltage iontophoresis technique. Statistical analysis was performed using Box-Behnken design to optimize the transungual delivery of terbinafine by examining crucial variables namely concentration of polyethylene glycol, voltage, and duration of application (2-6 h). Optimization data in batches (F1-F17) demonstrated that chemical enhancer, applied voltage, and application time have influenced terbinafine nail delivery. Higher ex vivo permeation and drug accumulation into the nail tissue were noticed in the optimized batch (F8) when compared with other batches (F1-F17). A greater amount of terbinafine was released across the nails when the drug was accumulated by iontophoresis than the passive counterpart. A remarkably higher zone of inhibition was observed in nails with greater drug accumulation due to iontophoresis, as compared to the passive process. The results here demonstrate that the optimized formulation with low voltage iontophoresis could be a viable and alternative tool in the transungual delivery of terbinafine, which in turn could improve the success rate of topical nail therapy in onychomycosis.

Insights into drug delivery across the nail plate barrier.

Topical therapy is at the forefront in treating nail ailments (especially onychomycosis and nail psoriasis) due to its local effects, which circumvents systemic adverse events, improves patient compliance and reduces treatment cost. However, the success of topical therapy has been hindered due to poor penetration of topical therapeutics across densely keratinized nail plate barrier. For effective topical therapy across nail plate, ungual drug permeation must be enhanced. Present review is designed to provide an insight into prime aspects of transungual drug delivery viz. nail structure and physiology, various onychopathies, techniques of nail permeation enhancement and in vitro models for trans-nail drug permeation studies. Updated list of drug molecules studied across the nail plate and key commercial products have been furnished with sufficient depth. Patents pertinent to, and current clinical status of transungual drug delivery have also been comprehensively reviewed. This is the first systematic critique encompassing the detailed aspects of transungual drug delivery. In our opinion, transungual drug delivery is a promising avenue for researchers to develop novel formulations, augmenting pharmaceutical industries to commercialize the products for nail disorders.