Evaluation of the Neo-Sensitabs diffusion method for determining the antifungal susceptibilities of Cryptococcus gattii isolates, using three different agar media

Unraveling the Impact of the Oil Phase on the Physicochemical Stability and Skin Permeability of Melatonin Gel Formulations

Melatonin's antioxidant properties make it a valuable component in anti-aging semisolid topical products. This study explores the role of Pemulen®, an acrylic-based viscosifying agent, in stabilizing cream-gel formulations. Remarkably, even at low concentrations (0.4%), Pemulen® successfully produced physicochemical stable topical formulations. In this work, the impact of the ratio of the oily phase-comprising olive oil and isopropyl myristate from 0 to 20%-was investigated to understand the internal microstructure effect on skin permeability, rheological properties, and stability. The formulations exhibited pseudoplastic behavior, with a significant positive correlation (p-value < 0.1) between the oily phase ratio, viscosity, spreadability, skin adhesiveness, and permeability. Formulations without the oil phase exhibited greater skin permeability. However, higher oily phase content enhanced viscosity, spreadability, and skin adhesion. Given that melatonin primarily degrades through oxidation, incorporating antioxidant excipients in semisolid formulations is crucial for maintaining its chemical stability. A quality by design (QbD) approach was used to assess the impact of four excipients-(a) DL-α-tocopheryl acetate (0.05%), (b) ascorbic acid (0.1%), (c) ethylene diamine tetraacetic acid (0.1%), and (d) sodium metabisulphite (0.5%)-on melatonin's stability. Our findings indicate that maintaining the physical stability of the formulation with a 20% oil phase is more critical for protecting melatonin from oxidation than merely adding antioxidant excipients.

Co-Delivery of a High Dose of Amphotericin B and Itraconazole by Means of a Dry Powder Inhaler Formulation for the Treatment of Severe Fungal Pulmonary Infections

Over the past few decades, there has been a considerable rise in the incidence and prevalence of pulmonary fungal infections, creating a global health problem due to a lack of antifungal therapies specifically designed for pulmonary administration. Amphotericin B (AmB) and itraconazole (ITR) are two antifungal drugs with different mechanisms of action that have been widely employed in antimycotic therapy. In this work, microparticles containing a high dose of AmB and ITR (20, 30, and 40% total antifungal drug loading) were engineered for use in dry powder inhalers (DPIs) with an aim to improve the pharmacological effect, thereby enhancing the existing off-label choices for pulmonary administration. A Design of Experiment (DoE) approach was employed to prepare DPI formulations consisting of AmB-ITR encapsulated within γ-cyclodextrin (γ-CD) alongside functional excipients, such as mannitol and leucine. In vitro deposition indicated a favourable lung deposition pattern characterised by an upper ITR distribution (mass median aerodynamic diameter (MMAD) ~ 6 µm) along with a lower AmB deposition (MMAD ~ 3 µm). This offers significant advantages for treating fungal infections, not only in the lung parenchyma but also in the upper respiratory tract, considering that Aspergillus spp. can cause upper and lower airway disorders. The in vitro deposition profile of ITR and larger MMAD was related to the higher unencapsulated crystalline fraction of the drug, which may be altered using a higher concentration of γ-CD.

Design of Micelle Nanocontainers Based on PDMAEMA-b-PCL-b-PDMAEMA Triblock Copolymers for the Encapsulation of Amphotericin B

The clinical application of amphotericin B (AmB), a broad spectrum antifungal agent, is limited by its poor solubility in aqueous medium and also by its proven renal toxicity. In this work, AmB was encapsulated in micelles obtained from the self-assembly of PDMAEMA-b-PCL-b-PDMAEMA triblock copolymers. The amount of encapsulated AmB depended on the copolymer composition, and short blocks of polycaprolactone (PCL) and poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) showed better performance. All the studied formulations exhibited a controlled release of AmB along 150 h. The formulations presented reduced hemotoxicity while maintaining antifungal activities against Candida albicans, Candida krusei, and Candida glabrata comparable with free AmB. A reduction on the hemotoxicity was found to be due to the slow release and subsequent low aggregation achieved with the use of polymer micelle nanocontainers.