Ibrutinib topical delivery for melanoma treatment: The effect of nanostructured lipid carriers' composition on the controlled drug skin deposition

Melanoma is responsible for more than 80% of deaths related to skin diseases. Ibrutinib (IBR), a Bruton's tyrosine kinase inhibitor, has been proposed to treat this type of tumor. However, its low solubility, extensive first-pass effect, and severe adverse reactions with systemic administration affect therapeutic success. This study proposes developing and comparing the performance of two compositions of nanostructured lipid carriers (NLCs) to load IBR for the topical management of melanomas in their early stages. Initially, the effectiveness of IBR on melanoma proliferation was evaluated in vitro, and the results confirmed that the drug reduces the viability of human melanoma cells by inducing apoptosis at a dose that does not compromise dermal cells. Preformulation tests were then conducted to characterize the physical compatibility between the drug and the selected components used in NLCs preparation. Sequentially, two lipid compositions were used to develop the NLCs. Formulations were then characterized and subjected to in vitro release and permeation tests on porcine skin. The NLCs containing oleic acid effectively controlled IBR release over 24 h compared to the NLCs composed of pomegranate seed oil. Furthermore, the nanoparticles acted as permeation enhancers, increasing the fluidity of the lipids in the stratum corneum, as determined by EPR spectroscopy, which stimulated the IBR penetration more profoundly into the skin. However, the NLCs composition also influenced the permeation promotion factor. Thus, these findings emphasize the importance of the composition of NLCs in controlling and increasing the skin penetration of IBR and pave the way for future advances in melanoma therapy.

Conformational analysis and spectroscopic properties of antichagasic nifurtimox

Considering the health relevance of Chagas' disease, recent research efforts have focused on developing more efficient drug delivery systems containing nifurtimox (NFX). This paper comprehensively investigates NFX through conformational analysis and spectroscopic characterization. Using a conformer-rotamer ensemble sampling tool (CREST-xtb), five distinct conformers of NFX were sampled within a 3.0 kcal mol-1 relative energy window. Subsequently, such structures were used as inputs for geometry optimization by density functional theory (DFT) at B3LYP-def2-TZVP level of theory. Notably, harmonic vibrational frequencies were calculated to establish an in-depth comparison with experimental results and existing literature for the NFX or similar molecules and functional groups, thereby achieving a widely reasoned assignment of the mid-infrared band absorptions for the first time. Moreover, UV-VIS spectra of NFX were obtained in several solvents, enabling the determination of the molar absorptivity coefficient for the two electronic transitions observed for NFX. Among the aprotic solvents, a bathochromic effect was observed in the function of the dielectric constants. Furthermore, a hypochromic effect was observed when the drug was dissolved in protic solvents. These findings offer crucial support for new drug delivery systems containing NFX while demonstrating the potential of spectrophotometric studies in establishing quality control assays for NFX drug products.

Melt crystallization and thermal degradation profile of the antichagasic drug nifurtimox

Despite nifurtimox (NFX) being a traditional drug for treating Chagas disease, some of its physicochemical properties are still unknown, especially its thermal behavior, which brings important outcomes regarding stability and compatibility. In this work, a comprehensive study of NFX's thermal properties was conducted to assist incremental innovations that can improve the efficacy of this drug in novel pharmaceutical products. For this purpose, thermal analyses associated with spectroscopy and spectrometry techniques were used. DSC analyses revealed that the melt crystallization of the NFX led to its amorphous form with the possible formation of a minor fraction of a different crystalline phase. Coats-Redfern method using TGA results indicated the activation energy of NFX non-isothermal degradation as 348.8 ± 8.2 kJ mol-1, which coincides with the C-NO2 bond dissociation energy of the 2-nitrofuran. Investigation of the isothermal degradation kinetics using FTIR 2D COS showed the possible detachment of radical NO2 and ethylene from the NFX structure, which could affect its mechanism of action. A preliminary mechanism for the thermal degradation of this drug was also proposed. The results enhanced the understanding of NFX's thermal properties, providing valuable insights, especially for developing NFX-based pharmaceutical products that involve thermal processing.

Chromatographic method for dacarbazine quantification in skin permeation experiments

Dacarbazine (DTIC) is a chemotherapeutic drug currently used for the systemic treatment of melanomas. Considering the easy access to these tumors, a topical route of drug administration could provide a more comfortable and less toxic treatment. However, DTIC quantification aiming at the design of topical formulations is challenging, pondering all the interferents present in the drug samples recovered from the skin. Hence, this work intended to validate a selective chromatographic method for DTIC determination in skin permeation studies. A reversed-phase C18 column was used as a stationary phase, and gradient elution of a mobile phase consisting of methanol and pH 6.5 sodium phosphate monohydrate buffer (0.01 mol/L) at a flow rate of 1.0 mL/min was implemented. DTIC was detected at 364 nm. The method was selective against skin interferents, linear (r = 0.9995) in a concentration range of 1.0-15.0 μg/mL, precise with an overall variation coefficient lower than 3.8%, accurate achieving recovery from the skin layers within 91-112%, and sensitive for the proposed application (detection limit = 0.10 μg/ mL, quantification limit = 0.30 μg/mL). Furthermore, the analytical method was successfully tested in in vitro skin permeation studies. In conclusion, the developed method is appropriate for DTIC analysis from the skin sample matrix.

Colloidal copper oxide nanoparticles leading to a biphasic dose-response in growth inhibition of Staphylococcus aureus

Aim: The dose response in growth inhibition of Staphylococcus aureus treated with colloidal copper oxide nanoparticles (CuO-NP) was evaluated. Methods: An in vitro microbial viability assay was conducted with CuO-NP concentrations spreading over the 0.4-848.0 μg/ml range. The dose-response curve was modeled with a double Hill equation. UV-Visible absorption and photoluminescence spectroscopies allowed tracking concentration-dependent modifications in CuO-NP. Results: Two specific phases separated by the critical concentration of 26.5 μg/ml were observed in the dose-response curve, with each exhibiting proper IC₅₀ parameters, Hill coefficients, and relative amplitudes. Spectroscopy techniques reveal the occurrence of a concentration-triggered aggregation of CuO-NP starting from this critical concentration. Conclusion: The findings demonstrate a dose-related change in S. aureus sensitivity to CuO-NP, which probably arises from the aggregation of this agent.

Cyclodextrin inclusion complex of a multi-component natural product by hot-melt extrusion

This study aimed to investigate whether hot-melt extrusion (HME) processing can promote molecular encapsulation of a multi-component natural product composed of volatile and pungent hydrophobic substances (ginger oleoresin (OR)) with cyclodextrins. 6-Gingerol and 6-shogaol, the biomarkers of ginger OR, were quantified by HPLC. Phase-solubility studies were performed using β-cyclodextrin (βCD) and hydroxypropyl-β-cyclodextrin (HPβCD) for ginger OR complexation. Solid complexes were then prepared by thermal (HME)- and solvent (slurry (SL))-based methods. Morphology, thermal behavior, solubility, in vitro dissolution, and in vivo anti-inflammatory activity were evaluated. HPβCD gave rise to AL-type complexes with ginger OR, whereas βCD led to materials with limited solubility. Ginger OR was complexed with HPβCD by HME without significant change in gingerol and shogaol content. Additionally, thermogravimetric analysis (TGA) suggested higher volatile retention in HME complexes than in SL ones. Shogaol and gingerol solubility and dissolution significantly increased from SL and HME complexes compared with ginger OR. In turn, 1:2 OR/HPβCD HME complex showed higher 6-shogaol solubility than SL, associated with a gradual release. The carrageenan-induced pleurisy test showed that the anti-inflammatory activity of ginger OR was maintained after complexation with HPβCD. The complexes significantly decrease the levels of IL-1β and inhibit cell migration. HME complex showed performance equivalent to the positive control and superior to the SL material. Taken together, these results indicate that HME can be useful for promoting the molecular encapsulation of complex natural products that contain volatile and thermolabile substances. HME complexes showed better in vivo and in vitro performance than complexes prepared using the solvent-based method.

Iontophoresis application for drug delivery in high resistivity membranes: nails and teeth

Iontophoresis has been vastly explored to improve drug permeation, mainly for transdermal delivery. Despite the skin's electrical resistance and barrier properties, it has a relatively high aqueous content and is permeable to many drugs. In contrast, nails and teeth are accessible structures for target drug delivery but possess low water content compared to the skin and impose significant barriers to drug permeation. Common diseases of these sites, such as nail onychomycosis and endodontic microbial infections that reach inaccessible regions for mechanical removal, often depend on time-consuming and ineffective treatments relying on drug's passive permeation. Iontophoresis application in nail and teeth structures may be a safe and effective way to improve drug transport across the nail and drug distribution through dental structures, making treatments more effective and comfortable for patients. Here, we provide an overview of iontophoresis applications in these "hard tissues," considering specificities such as their high electrical resistivity. Iontophoresis presents a promising option to enhance drug permeation through the nail and dental tissues, and further developments in these areas could lead to widespread clinical use.

Effects of Formulation and Manufacturing Process on Drug Release from Solid Self-emulsifying Drug Delivery Systems Prepared by High Shear Mixing

This study sought to investigate the influence of formulation and process factors of the high shear mixing (HSM) on the properties of solid self-emulsifying drug delivery systems (S-SEDDS) containing the model drug carvedilol (CAR). Firstly, liquid SEDDS (L-SEDDS) were prepared by mixing castor oil with different proportions of surfactant (Solutol or Kolliphor RH40) and cosolvent (Transcutol or PEG400). A miscible L-SEDDS with high drug solubility (124.3 mg/g) was selected and gave rise to 10% (m/m) CAR loaded-emulsion with reduced particle size. Then, a factorial experimental design involving five component's concentration and two process factors was used to study the solidification of the selected L-SEDDS by HSM. CAR content, diffractometric profile, and in vitro dissolution were determined. Morphological and flow analyses were also performed. Porous and spherical particles with mean sizes ranging from 160 to 210 µm were obtained. Particle size was not affected by any formulation factor studied. Powder flowability, in turn, was influenced by L-SEDDS and crospovidone concentration. CAR in vitro dissolution from S-SEDDS was significantly increased compared to the drug as supplied and was equal (pH 1.2) or lower (pH 6.8) than that determined for L-SEDDS. Colloidal silicon dioxide decreased drug dissolution, whereas an increase in water-soluble diluent lactose and L-SEDDS concentration increased CAR dissolution. The proper selection of liquid and solid constituents proved to be crucial to developing an S-SEDDS by HSM. Indeed, the results obtained here using experimental design contribute to the production of S-SEDDS using an industrially viable process.

New perspectives on the topical management of recurrent candidiasis

Candidiasis is a common opportunistic infection caused by fungi of the Candida genus that affects mainly mucocutaneous tissues (e.g., vaginal, oral, and mammary). This condition has been known for a long time; thus, innumerous topical and systemic treatments are already available on the market worldwide. Yet, recurrent superficial candidiasis (RSC) is an expected outcome, still lacking effective and convenient treatments. Although several individual conditions may contribute to disease recurrence, biofilms' presence seems to be the main etiological factor contributing to antifungal resistance. More than proposing novel antifungal agents, current research seems to be focusing on improving the pharmaceutical technology aspects of formulations to address such a challenge. These include extending and improving intimate contact of drug delivery systems with the mucocutaneous tissues, increasing drug loading dose, and enhancing topical drug permeation. This review discusses the current understanding of the RSC and the use of pharmaceutical technology tools in obtaining better results. Even though several drawbacks of conventional formulations have been circumvented with the help of nano- or microencapsulation techniques and with the use of mucoadhesive formulation excipients, many challenges remain. In particular, the need to mask the unpalatable taste of formulations for the treatment of oral candidiasis, and the necessity of formulations with a "dryer" sensorial feeling and improved performances in providing higher bioavailability for the treatment of mammary and vaginal candidiasis.