Purva Thatai

A critical appraisal of microemulsions for drug delivery: part II

Microemulsions are thermodynamically stable, optically transparent isotropic solutions of oil and water successfully formulated by using a combination of suitable surfactant and cosurfactant. The solubilization power of microemulsions for lipophilic, hydrophilic and amphiphilic solutes form a viable approach for enhancing the bioavailability of hydrophobic drugs and percutaneous permeation of poorly permeable drugs, mainly due to the large area per volume ratio available for mass transfer. Microemulsions have emerged as novel vehicles for drug delivery due to their versatile applications. They allow sustained release for topical, oral, nasal, intravenous, ocular, parenteral and other administration routes of drugs. They also offer a relevant application platform for improving target specificity, therapeutic activity, and reducing toxicity of drugs.

Terbinafine hydrochloride nail lacquer for the management of onychomycosis: formulation, characterization and in vitro evaluation

AIM The present investigations intention was to develop an optimized nail lacquer (NL) for the management of onychomycosis. MATERIALS & METHODS The NL was optimized statistically adopting 32 full factorial design having different polymer ratios and solvent ratios. The formulations were assessed for drug permeation drying time and peak adhesive strength of the film. Characterization was done using techniques including attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), x-ray diffraction (XRD), etc. RESULTS & CONCLUSION The formulation that had 1:1 polymer ratio and 80:20 solvent ratio was chosen as the optimized formulation. In vitro permeation studies showed better penetration (∼3.25-fold) as well as retention (∼11-fold) of the optimized NL formulation in the animal hoof as compared with the commercial formulation. The findings of in vitro and ex vivo studies elucidated the potential of the optimized formulation. [Formula: see text].

Progressive development in experimental models of transungual drug delivery of anti-fungal agents.

Pre‐clinical development comprises of different procedures that relate drug discovery in the laboratory for commencement of human clinical trials. Pre‐clinical studies can be designed to recognize a lead candidate from a list to develop the procedure for scale‐up, to choose the unsurpassed formulation, to determine the frequency, and duration of exposure; and eventually make the foundation of the anticipated clinical trial design. The foremost aim in the pharmaceutical research and industry is the claim of drug product quality throughout a drugs life cycle. The particulars of the pre‐clinical development process for different candidates may vary; however, all have some common features. Typically in vitro, in vivo or ex vivo studies are elements of pre‐clinical studies. Human pharmacokinetic in vivo studies are often supposed to serve as the ‘gold standard’ to assess product performance. On the other hand, when this general assumption is revisited, it appears that in vitro studies are occasionally better than in vivo studies in assessing dosage forms. The present review is compendious of different such models or approaches that can be used for designing and evaluation of formulations for nail delivery with special reference to anti‐fungal agents.

Skin cancer: symptoms, mechanistic pathways and treatment rationale for therapeutic delivery

Cancer is a group of diseases categorized by abandoning escalation and multiplication of abnormal cells. Current topical treatments for skin cancer are mainly in the semisolid dosage forms of 5-fluorouracil, imiquimod, etc. Many surgical treatments are also available these days for the treatment of skin cancer, for example, photodynamic therapy, which is approved by the US FDA. The stratum corneum is the main barrier against permeation of topical formulations developed for skin cancer treatment. Liposomes, thermosensitive stealth liposomes, nanoemulsions and polymeric lipid nanoparticles have been used by several researchers to increase skin permeability. In the present paper, major aspects of formulations developed for skin cancer, various types of skin cancer, its etiology and pathogenesis have been emphasized.

Transungual Gel of Terbinafine Hydrochloride for the Management of Onychomycosis: Formulation, Optimization, and Evaluation

The present study was aimed to optimize, develop, and evaluate microemulsion and microemulsion-based gel as a vehicle for transungual drug delivery of terbinafine hydrochloride for the treatment of onychomycosis. D-optimal mixture experimental design was adopted to optimize the composition of microemulsion having amount of oil (X1), Smix (mixture of surfactant and cosurfactant; X2), and water (X3) as the independent variables. The formulations were assessed for permeation (micrograms per square centimeter per hour; Y1), particle size (nanometer; Y2), and solubility of the drug in the formulation (milligrams per milliliter; Y3). The microemulsion containing 3.05% oil, 24.98% Smix, and 71.96% water was selected as the optimized formulation. The microemulsion-based gel showed better penetration (∼5 folds) as well as more retention (∼9 fold) in the animal hoof as compared to the commercial cream. The techniques used to screen penetration enhancers (hydration enhancement factor, ATR-FTIR, SEM, and DSC) revealed the synergistic effect of combination of urea and n-acetyl cysteine in disruption of the structure of hoof and hence, leading to enhanced penetration of drug.

Is This the Right Drug or the Dose for the Management of Onychomycosis

Onychomycosis is a fungal infection of the toenails and fingernails that results in thickening, discoloration, splitting as well as lifting of the nails from the nail bed. It affects 14% of the total world population, with more prevalence in elders and diabetics. Both dermatophytes (Trichophyton rubrum or T. mentagrophytes) and nondermatophytes (Scopulariopsis brevicaulis, Aspergillus spp, Fusarium spp, and sometimes Candida spp) have been identified as etiologic agents of onychomycosis. The treatment of onychomycosis is known to be challenging since it is a chronic condition, difficult to eradicate and tends to relapse [1]. The pharmacotherapy of onychomycosis involves prolonged systemic or oral antifungal therapy due to slow overturn rate of nail as well as limited blood circulation into the affected nail bed. However, complete cure that involves a clinical cure (normal nail morphology) and mycological cure (both negative microscopy and dermatophyte culture), is often unattainable. In recent years the development of antifungal drugs of second generation (fluconazole, itraconazole, and terbinafine) has produced notable, long-term cure rates with shorter treatment period and improved safety profiles as compared to the first generation antifungal agents. However, different dosage regimens of various antifungal agents have been used by various researchers in clinical trials in order to ensure the complete eradication of the fungal infection in a shorter period with better efficacy.

Structural and component mining of nails using bioengineering techniques

The human nail is one of the challenging membranes for the scientists to target and to improve the clinical efficacy of ungual formulations. The understanding of nail physiology, impact of hydration on its properties and presence of trace elements in nails as biomarkers has been explored by various researchers in clinical studies. Despite the importance of biophysical techniques for the assessment of structure and physiology of nail, minimum literature analyses biophysical, biochemical and bioanalytical approaches. However, nowadays scientists in bioengineering field are keen in developing non‐invasive, reliable and reproducible techniques for the assessment of different anatomical and functional parameters of nails for testing of ungual products.

Surging footprints of mathematical modeling for prediction of transdermal permeability

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Critical review on retrospective and prospective changes in antifungal susceptibility testing for dermatophytes.

Antifungal susceptibility testing is a progressive field of mycology with respect to dermatophytes as well as non‐dermatophytes. Documentation and approval regarding standardisation of in vitro susceptibility testing have been done by different governing bodies such as Clinical and Laboratory Standards Institute, European Committee on Antimicrobial Susceptibility Testing and British Society of Antimicrobial Chemotherapy. The process of standardisation and approval started in 1985 with certain amendments in 2002 and 2004. In case of dermatophytes, antifungal susceptibility testing protocol has been approved recently in 2008; however, the approved standardisation also needs certain amendments/modifications due to the limitations of an existing method. In the present review, we have compiled these standardisation techniques along with the limitations and advantages and the amendments that have been proposed at different time periods by different researchers and regulatory agencies.