Single crystal structure, solid state characterization and dissolution rate of terbinafine hydrochloride

Novel First-Generation Dissolution Models to Investigate the Release and Uptake of Oral Lymphotropic Drug Products

Conventional dissolution tests only assess the aqueous release of drugs to ensure quality and performance, without indicating whether absorption occurs through the portal or the lymphatic circulation. To address this issue, this study aimed to develop novel first-generation dissolution models that could investigate the release and uptake of oral lymphotropic drugs and examine relevant formulation issues. Dissolution of three commercial lymphotropic drug products (Terbinafina, Apo-terbinafine, and Lamisil) was done using modified versions of USP Apparatus II and IV. The developed models contained a lymphatic compartment filled with artificial chylomicrons to account for absorption through intestinal lymphatic pathway. The various products exhibited different release profiles into the aqueous media and the lymphatic media across the two tested models. The modified USP IV apparatus demonstrated greater distinction in aqueous release patterns. However, the release pattern into the lymphatic media remained similar in both models. This work represents a progress in meeting the challenges posed by the increasing complexity of pharmaceutical products containing lipophilic drugs or formulations, and has the potential to contribute towards the development of in-vitro bioequivalence standards for formulations targeting intestinal lymphatics.

Topical Delivery of Terbinafine HCL Using Nanogels: A New Approach to Superficial Fungal Infection Treatment

This study investigated pH-responsive Terbinafine HCL (TBH)-loaded nanogels as a new approach to treating superficial fungal infections. Acrylic acid (AA) is a synthetic monomer that was crosslinked with a natural polymer (gelatin) using a free radical polymerization technique to fabricate gelatin-g-poly-(acrylic acid) nanogels. Ammonium persulphate (APS) and N, N'-methylene bisacrylamide (MBA) were used as the initiator and crosslinker, respectively. Developed gelatin-g-poly-(acrylic acid) nanogels were evaluated for the swelling study (pH 1.2, 5, 7.4), DEE, particle size, FTIR, thermal stability (TGA, DSC), XRD, SEM, DEE, and in vitro drug release study to obtain optimized nanogels. Optimized nanogels were incorporated into 1% HPMC gel and then evaluated in comparison with Lamisil cream 1% for TBH stratum corneum retention, skin irritation, and in vitro and in vivo antifungal activity studies. Optimized nanogels (AAG 7) demonstrated a 255 nm particle size, 82.37% DEE, pH-dependent swelling, 92.15% of drug release (pH) 7.4 within 12 h, and a larger zone of inhibition compared to Lamisil cream. HPMC-loaded nanogels significantly improved the TBH skin retention percentage, as revealed by an ex vivo skin retention study, indicating the usefulness of nanogels for topical use. In vivo studies conducted on animal models infected with a fungal infection have further confirmed the effectiveness of nanogels compared with the Lamisil cream. Hence, Gelatin-g-poly-(acrylic acid) nanogels carrying poorly soluble TBH can be a promising approach for treating superficial fungal infections.

Quality by Design Guided Development of Polymeric Nanospheres of Terbinafine Hydrochloride for Topical Treatment of Onychomycosis Using a Nano-Gel Formulation

Superficial fungal diseases of the skin and nails are an increasingly common occurrence globally, requiring effective topical treatment to avoid systemic adverse effects. Polymeric nanoparticles have demonstrated sustained and effective drug delivery in a variety of topical formulations. The aim of this project was to develop polymeric antifungal nanospheres containing terbinafine hydrochloride (TBH) to be loaded into a hydrogel formulation for topical nail drug delivery. A quality by design (QbD) approach was used to achieve optimized particles with the desired quality target product profile (QTPP). Polyvinyl alcohol (PVA) at 2% w/v and a drug to polymer ratio of 1:4, together with a robust set of processes and material attributes, resulted in nanoparticles of 108.7 nm with a polydispersity index (PDI) of 0.63, 57.43% recovery, and other desirable characteristics such as zeta potential (ZP), particle shape, aggregation, etc. The nanospheres were incorporated into a carbomer-based gel, and the delivery of TBH through this formulation was evaluated by means of in vitro drug release testing (IVRT) and ex vivo nail permeation study. The gel containing the TBH nanospheres demonstrated a slower and controlled drug release profile compared with the control gel, in addition to a more efficient delivery into the nail. These antifungal nanospheres can be utilized for topical therapy of a multitude of superficial fungal infections.

Development of Solvent-Free Co-Ground Method to Produce Terbinafine Hydrochloride Cyclodextrin Binary Systems; Structural and In Vitro Characterizations

Molecular complexation with cyclodextrins (CDs) has long been a known process for modifying the physicochemical properties of problematic active pharmaceutical ingredients with poor water solubility. In current times, the focus has been on the solvent-free co-grinding process, which is an industrially feasible process qualifying as a green technology. In this study, terbinafine hydrochloride (TER), a low solubility antifungal drug was used as a model drug. This study aimed to prepare co-ground products and follow through the preparation process of the co-grinding method in the case of TER and two amorphous CD derivatives: (2-hydroxypropyl)-β-cyclodextrin (HPBCD); heptakis-(2,6-di-O-methyl)-β-cyclodextrin (DIMEB). For this evaluation, the following analytical tools and methods were used: phase solubility studies, differential scanning calorimetry (DSC), X-ray powder diffractometry (XRPD), hot-stage X-ray powder diffractometry (HOT-XRPD), Fourier-transform infrared (FT-IR), Raman spectroscopy, and Scanning Electron Microscopy (SEM). Furthermore, in vitro characterization (dissolution and diffusion studies) was performed in two kinds of dissolution medium without enzymes. In the XRPD and SEM studies, it was found that the co-grinding of the components resulted in amorphous products. FT-IR and Raman spectroscopies confirmed the formation of an inclusion complex through the unsaturated aliphatic chain of TER and CDs. In vitro characterization suggested better dissolution properties for both CDs and decreased diffusion at higher pH levels in the case of HPBCD.

Printing Drugs onto Nails for Effective Treatment of Onychomycosis

Inkjet printing (IJP) is an emerging technology for the precision dosing of medicines. We report, for the first time, the printing of the antifungal drug terbinafine hydrochloride directly onto nails for the treatment of onychomycosis. A commercial cosmetic nail printer was modified by removing the ink from the cartridge and replacing it with an in-house prepared drug-loaded ink. The drug-loaded ink was designed so that it was comparable to the commercial ink for key printability properties. Linear drug dosing was shown by changing the lightness of the colour selected for printing (R² = 0.977) and by printing multiple times (R² = 0.989). The drug loads were measured for heart (271 µg), world (205 µg) and football (133 µg) shapes. A disc diffusion assay against Trpytophan rubrum showed inhibition of fungal growth with printed-on discs. In vitro testing with human nails showed substantial inhibition with printed-on nails. Hence, this is the first study to demonstrate the ability of a nail printer for drug delivery, thereby confirming its potential for onychomycosis treatment.

Terbinafine Hydrochloride Combined With Itraconazole for Fungal Skin Diseases: A Randomized Controlled Trial

BACKGROUND

Terbinafine and itraconazole are the common antifungal drugs in clinic. In vitro experiments proved that terbinafine combined with itraconazole achieves better antifungal effects. However, clinical study addressing this issue was still scarce.

STUDY QUESTION

Terbinafine combined with itraconazole achieves better therapeutic effects in fungal skin diseases.

STUDY DESIGN

Approximately 178 patients with fungal skin diseases from Meizhou People's Hospital, China, between October 2016 and October 2017 were admitted to this study. Patients were randomly distributed to 3 groups by randomly selecting random numbers and were treated with terbinafine, itraconazole, monotherapy, or combined therapy. Both patients and study investigators were unaware of grouping situations during experiments. Fifteen patients were excluded due to poor compliance, and 11 patients were excluded due to incomplete data. Finally, 152 patients were analyzed for this study.

MEASURES AND OUTCOMES

The therapeutic effects were evaluated by clinic symptom scores, mycology examination, the cure rate, and the cure time. Adverse events, relapse of disease, and patient's satisfaction level were recorded during follow-up.

RESULTS

In the terbinafine + itraconazole group, at 14 days after treatment, the symptom scores were significantly decreased, compared with the terbinafine or itraconazole group (P1 < 0.05, P2 < 0.05). At 28 days after treatment, the fungal infection of 37 patients was eradicated, which were significantly more than 26 patients in the terbinafine group and 19 patients in the itraconazole group (P1 < 0.05, P2 < 0.05). The terbinafine + itraconazole group also exhibited 100% cure rate of patients with fungal skin diseases, shorter cure time, and increased number of cured patients during the same treatment period, which was better than terbinafine or itraconazole monotherapy (P1 < 0.05, P2 < 0.05). In addition, no adverse events and no relapse of fungal disease were reported in the terbinafine + itraconazole group during follow-up. Ninety-eight percent patients were satisfied with the therapeutic effects of combined treatment.

CONCLUSIONS

Compared with terbinafine or itraconazole monotherapy, terbinafine + itraconazole combined treatment achieves better therapeutic effects in fungal skin diseases.

Fabrication of Dissolvable Microneedle Patches Using an Innovative Laser-Cut Mould Design to Shortlist Potentially Transungual Delivery Systems: In Vitro Evaluation

There has been a great interest towards transungual delivery systems due to limited drug penetration for the treatment of nail diseases. More important, antifungal oral medicaments used may cause serious side effects including liver damage. Therefore, we propose non-oral dissolvable microneedle (MN) patch to strike the poor permeability of the nail. We report the design of MN patch mould using a laser-cutting machine and solvent casting of several hydrophilic polymers to fabricate these MN patches. Formulations were evaluated for their in vitro release and penetration properties and selected based on physical characterization for compatibility (differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD)), dimension repeatability and drug content uniformity. A 72-array of cone-shaped MN patch mould was successfully constructed on polymethylmethacrylate sheets. Interval and frequency of laser exposure were pivotal to determine the needle sharpness, attained unexpectedly at a low level of circa 30 μm. F1 platform of polyvinyl alcohol, kollicoat IR®, ethylene glycol and gelatin showed circa 74% penetration of methylhydroxy-4-benzoate (F1(A)) over 24 h, whereas F2 (same as F1-A with the addition of poloxamer 338) resulted in an almost 42% of this drug retention in the bovine hoof (24 h). Both formulations are likely to be useful for onychomycosis treatment. F1 polymers also afford enhanced permeability (almost 73.5% after 24 h) of terbinafine hydrochloride into the hoof (F1(B)). However, F3 (chitosan, gelatin and ethylene glycol) presents the prospect of developing MN patch for this drug with almost complete hoof penetration (circa 96.3% after 24 h). All medicated formulations have shown similar mechanical properties after ageing for 1 year under dry conditions.

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

AIM

The present investigation's 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].

In vitro synergism of a water insoluble fraction of Uncaria tomentosa combined with fluconazole and terbinafine against resistant non-Candida albicans isolates

CONTEXT

Uncaria tomentosa D.C. (Rubiaceae) has several biological activities, including activity against resistant Candida strains. The synergistic interaction with terbinafine or fluconazole can be an important alternative to overcome this resistance.

OBJECTIVES

The potential synergy between a water insoluble fraction (WIF) from Uncaria tomentosa bark and the antifungals terbinafine (TRB) and fluconazole (FLZ) against non-Candida albicans resistant strains was investigated.

MATERIALS AND METHODS

TRB and FLZ, alone and combined with WIF, were tested by the checkerboard procedure using the micro-dilution technique against seven isolates of Candida glabrata and C. krusei. The molecular interactions occurring outside the cell wall were evaluated by scanning electron microscopy, Fourier transform infrared (FT-IR) and differential scanning calorimetry (DSC) analysis.

RESULTS

The checkerboard inhibitory assay demonstrated synergy for WIF:TRB and WIF:FLZ combinations, respectively. The best synergistic cell damage was demonstrated unequivocally for the associations of WIF and TRB (1.95:4.0 μg/mL) and WIF and FLZ (1.95:8.0 μg/mL). The comparison of the FT-IR spectra of the antifungal alone, and in combination with WIF, allows recognizing clear differences in 3000, 1600, 1400, and 700-800 cm^-1 bands. Additionally, modifications on TRB and FLZ thermograms were clearly noticed after their combination with WIF.

CONCLUSIONS

DSC and infrared analysis demonstrated intermolecular interactions between WIF and either TRB or FLZ. Hence, quite likely the synergistic effect is related to interaction events occurring outside the cell wall between antifungal and cat's claw proanthocyanidins. A direct action on the cell wall is suggested, without connection with the ABC efflux pump mechanism.

Solid-State Form Characterization of Riparin I

Riparin I is an alkamide with potential anxiolytic activity in preclinical studies. The characterization and understanding of solid-state properties play an importance role in drug development. For this work, the solid state of five riparin I batches (RIP-1, RIP-2, RIP-3, RIP-4, and RIP-5), obtained by the same synthesis process, were characterized by Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), DSC-photovisual, Thermogravimetry (TG), Fourier Transform Infrared (FTIR), Pyrolysis (Pyr-GC/MS), X-ray Powder Diffraction (PXRD), and Solid-State Nuclear Magnetic Resonance (ssNMR) techniques. Batches of riparin I with different crystal habits resulting in crystallization impurities were observed, which can be attributed to the presence of triethylamine. The main differences were observed by DSC, PXRD, and ssNMR analysis. DSC curves of RIP-2 and RIP-3 presented endothermic peaks at different temperatures of fusion, which can be attributed to the mixture of different crystalline forms. PXRD and ssNMR results confirmed crystallinity differences. The results offer evidence of the importance of controlling the reproducibility of the synthesis in order to obtain the adequate morphology for therapeutic efficacy and avoiding future problems in quality control of riparin I products.

N-[1-Phenyl-2,5-bis(trimethylsilyl)pent-2-en-4-yn-1-yl]aniline

The molecular structure of the title compound, C23H31NSi2, reveals an acyclic conjugated enyne unit as the main feature. The central pent-2-en-4-yl fragment is essentially planar, with a maximum deviation of 0.0492 (7) Å from the mean plane defined by the C—C=C—C[triple-bond]C unit. The dihedral angle between the phenyl rings is 84.44 (5)°.

Role of solvents in improvement of dissolution rate of drugs: crystal habit and crystal agglomeration

Crystallization is often used for manufacturing drug substances. Advances of crystallization have achieved control over drug identity and purity, but control over the physical form remains poor. This review discusses the influence of solvents used in crystallization process on crystal habit and agglomeration of crystals with potential implication for dissolution. According to literature it has been known that habit modification of crystals by use of proper solvents may enhance the dissolution properties by changing the size, number and the nature of crystal faces exposed to the dissolution medium. Also, the faster dissolution rate of drug from the agglomerates of crystals compared with the single crystals may be related to porous structure of the agglomerates and consequently their better wettability. It is concluded from this review that in-depth understanding of role of the solvents in crystallization process can be applied to engineering of crystal habit or crystal agglomeration, and predictably dissolution improvement in poorly soluble drugs.

Crystal face identification by Raman microscopy for assessment of crystal habit of a drug

Crystal habit is one of the key crystallographic characteristics of active pharmaceutical ingredients (APIs), especially those that are poorly soluble. X-ray powder diffraction has commonly been used to assess crystal habit; however, it can only provide macro-information regarding crystal habit for a whole powder sample, not for individual crystals. We describe an approach that uses Raman microscopy for the identification of crystal faces to assess crystal habit at the individual particle level. An antiepileptic agent, phenytoin, was used as the model substance. Phenytoin crystals form a primitive orthorhombic cell. Raman microscopy was used to identify three different patterns of Raman spectra, corresponding to the crystallographic axis that was parallel to the polarization direction of the excitation laser. Thus, a combination of Raman spectra, in which the polarization direction was horizontal and vertical to the morphologically long axis of the crystal, characterized the crystal face. Phenytoin crystals were prepared under various conditions, and the horizontal/vertical combinations of Raman spectra were recorded for individual crystals. The dominantly exposed crystal faces for each condition were identified. This analytical method enables micro-view assessments of crystal habit, which are helpful for identifying the habits of APIs alone and in formulations.

Development and validation of an intrinsic dissolution method for nimodipine polymorphs

The polymorphs of nimodipine, Modification I (Mod I), the metastable racemate, and Modification II (Mod II), the stable conglomerate, were evaluated by means of the intrinsic dissolution procedure. For this purpose, a hydro alcoholic solution (ethanol:water, 50:50, v/v) was selected as the dissolution medium, maintained at 37±0.5°C. Different rotation speeds were tested (50, 75 and 100 rpm) and the lower one was chosen for the test validation. Although the sample initially characterized as polymorph Mod I presented higher intrinsic dissolution rates in all the conditions tested, no statistical differences were noticed between the two polymorphs. This result can be attributed to the partial solution-mediated phase transformation from Mod I to Mod II, detected through X-ray powder diffraction and differential scanning calorimetry. Also, reliable intrinsic dissolution rate data were acquired for the polymorph Mod II. The dissolution method was validated, being considered stable, specific, linear, sensible, accurate and precise.