A systematic approach to the formulation of anti-onychomycotic nail patches

What can GP data tell us about the treatment of onychomycosis in the UK?

Background

Treatment of onychomycosis is challenging, and there is much literature on optimal treatment strategies. In contrast, information on how onychomycosis is actually treated in primary care is scarce. Information on practice is important as it can reveal much, such as, to what extent national guidelines are followed and which population groups seek/receive treatment or do not do so.

Objectives

To describe the pattern of onychomycosis treatment in primary care in the UK, by patient's gender and age.

Methods

A population‐based retrospective cross‐sectional study was conducted. The Health Improvement Network (THIN) database was used to calculate incidence rates of onychomycosis in the years 2001–2017. The prescription of oral and topical anti‐fungal drugs to patients with onychomycosis was reviewed.

Results

THIN data showed an onychomycosis incidence rate of about 50 per 100,000. More males than females (52% vs. 48%), and more people aged 50–59 years had received treatment for onychomycosis. Oral terbinafine was the most commonly prescribed drug, followed by topical amorolfine, although terbinafine was used more commonly by men and amorolfine by women. Patients with onychomycosis were also prescribed other antifungals, including itraconazole, griseofulvin, tioconazole, ketoconazole shampoo, fluconazole and clotrimazole. A greater proportion of women, compared to men, were prescribed fluconazole.

Conclusions

Onychomycosis treatment in primary care in the UK is broadly in concordance with national guidelines.

A drug-in-adhesive anti-onychomycotic nail patch: Influence of drug and adhesive nature on drug release, ungual permeation, in vivo residence in human and anti-fungal efficacy

A nail patch is an attractive option for the topical treatment of onychomycosis, although no product is commercially available. We previously identified optimal nail patch formulations for two anti-onychomycotic drugs, based on their properties, as well as those of the other patch components. In this paper, our aim was to further investigate the potential of the patch formulations as topical nail medicines, in particular, whether the drug-in-adhesive patches release drug which then permeates into and through the nail plate and show anti-fungal efficacy, and whether and to what extent they remain adhered to the human nail plate in vivo when tested over 2 week durations. In addition, the influence of the drug (amorolfine HCl, ciclopirox olamine) and PSA (Duro-Tak 2852 or Duro-Tak 202A) on these parameters was determined. We found that both the nature of the drug and of the PSA influenced in vitro drug release. The nature of the drug, but not that of the PSA, influenced ungual drug permeation through human nail clippings, with considerably greater (almost double) permeation for ciclopirox olamine, the smaller and less lipophilic molecule. In vivo residence, tested with 3 out of the 4 patches, excluding the patch where ciclopirox olamine degraded with time, showed greater residence on toenails compared to fingernails reflecting their far lesser exposure to environmental stresses during daily activities. In vivo residence was enhanced when the patch was cut to the shape of the nail, was applied at bedtime, and when a clear colourless nail varnish was applied on top of the patch to 'seal' it into place on the nail. Comparison of the patches indicated greater residence of Duro-Tak 202A containing patches over those containing Duro-Tak 2852. Amorolfine HCl in Duro-Tak 202A based patch also showed antifungal efficacy in contrast to Duro-Tak 2852-based patch, and is particularly promising for further development as a potential toenail medicine, remaining almost fully adhered to toenails for at least two weeks.

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.

Design of a Long-Acting Rivastigmine Transdermal Delivery System: Based on Computational Simulation

The purpose of our study was using a computational simulation to develop a long-acting patch of rivastigmine (RVS). A range of patch formulations were screened including pressure sensitive adhesive (PSA), pharmaceutical excipients, and controlled release membranes using transfer simulation based on a mathematical model. Diffusion dynamics parameters for simulated operations were acquired through in vitro release tests (IVRT) and in vitro skin permeation tests (IVPT). The mechanism of controlled release was studied by FTIR (Fourier transform infrared), DSC (differential scanning calorimeter) and molecular docking. Results of a rat in vitro permeation profile showed excellent correlation with the in vivo deconvolution profile (R²=0.998). Experiments testified to transfer of RVS at a relatively uniform speed with high skin permeation (2531.2±142.46 μg/cm²) in 72 h. Pharmacokinetic data obtained in vivo also confirmed stable plasma concentrations over 72 h for the optimized patch, and significant prolongation of both T_max (11.20±1.79 h) and MRT_0-t (33.91±5.33 h). C_max was controlled with AUC_0-t (267.34±24.46 h ng/ml), which was closely comparable to parameters of a commercial Exelon® Patch. The successful development of a long-acting patch of RVS thus underscores the potential of computer aided design in a context of promnesic transdermal delivery. Graphical abstract.

Effect of plasticizers on drug-in-adhesive patches containing 5-fluorouracil

Topical patches containing 5-fluorouracil (5-FU) are a feasible alternative to overcome the shortcomings of commercial cream for the treatment of non-melanoma skin cancer (NMSC). Plasticizers are a critical component of drug-in-adhesive (DIA) patches as they can significantly affect the mechanical, adhesive and drug release characteristics of the patches. Eudragit® E (EuE) is a methacrylate-based cationic copolymer capable of producing flexible and adhesive films for topical application. In this study, the effect of plasticizers on the mechanical, adhesive and 5-FU release characteristics of EuE-based patches was comprehensively evaluated. While the elongation at break (%) and adhesion of the films were significantly increased with increasing triacetin, dibutyl sebacate (DBS) and triethyl citrate (TEC) concentrations, the tensile strength showed an inverse relationship. EuE plasticized with 40% triacetin, 30% DBS or 40% w/w TEC produced elastic and adhesive films most suitable for topical application. In vitro release studies of the 5-FU-loaded patches demonstrated an initial burst release pattern during the first 10 min followed by a slow release over 120 min. In summary, this study provides important information on effect of plasticizers for preparation of EuE-based patches with desired mechanical, adhesive and release characteristics of 5-FU towards their potential application in the treatment of NMSC.

The effect of various primers improving adhesiveness of gel polish hybrids on pH, TOWL and overall nail plates condition

BACKGROUND

Hybrid manicure is now a popular method of nail care and nail art, which is associated with its durability. Unfortunately, it has an adverse effect on pH, TOWL and overall nail plates condition and has not been investigated in detail so far.

AIMS

The aim of this study was to compare the pH and TOWL of the hand nails after using different primers. The effect of application time, breaks between applications and the method of curing and removal on those parameters and overall nail plates condition were evaluated.

PATIENTS/METHODS

An evaluation survey was conducted among 116 women. pH and TOWL measurements of the nail plate in 35 women were taken using the Courage & Khazaka. Clinical photos were made using the Fotomedicus system.

RESULTS

The measured pH values of the nail plate in the test group with gel polish hybrid on the nails were from 5.50 to 6.65, while after removal of the gel polish hybrid, the values ranged from 5.63 to 6.68. TOWL of the nail plate covered with gel polish hybrid ranged from 2.9 to 33.2 g/m² /h, whereas after removal of hybrids-from 1.9 to 45.7 g/m² /h.

CONCLUSION

Different forms of acid-free primers maintain a lower pH of the nail plate covered with a gel polish hybrid, while the acidic primer maintains higher values of the nail plate pH. The significant decrease in the nail plate TOWL following the application of gel polish hybrid indicates a reduced loss of water from the surface of the nail to the atmosphere.

Physicochemical investigations of native nails and synthetic models for a better understanding of surface adhesion of nail lacquers

The human nail, like any biological material, is not readily available in large amounts and shows some variability from one individual to another. Replacing it by synthetic models is of great interest to perform reproducible and reliable tests in order to assess drug diffusion or nail lacquer adhesion for example. Keratin films, produced at the lab scale from natural hair, and the commercially available Vitro-nail® sheets have been proposed as models of human nails. In this study, we have investigated in detail these two materials. Surface aspect, composition, surface energy and water permeation were determined by SEM-EDS, ATR-FTIR, XPS, DVS and tensiometry and were compared to those of nails clippings. The development of a probe tack test using a rotational rheometer allowed us to measure the adhesion of three different nail lacquers on each substrate and the results were correlated with the surface state. It is shown that except roughness, keratin films exhibit similar composition, water sorption and surface energy as human nails. Vitro-nail® presents a more hydrophilic and permeable behavior than natural nail due to probable higher proportions of amide functions and absence of disulfide bridges. With the aim to improve nail lacquer residence, the importance of adsorption, electrostatic and mechanical adhesions as well as water sorption behavior is highlighted and allowed to show the importance of roughness, a low surface energy, a moderate hydrophobicity and an ability to form hydrogen and electrostatic bonds in order to optimize adhesion.