Micro- and nanoemulsions are potential drug solubilizers and penetration enhancers through the high surfactant/co-surfactant content. This study aimed to evaluate the influence of minoxidil (MXD) solubilized in the microemulsions (MEs) on drug release by in vitro/ex vivo diffusion through the semi-permeable membrane Spectra/Por^® (Spectrum Laboratory, Gardena, CA, USA) and porcine ear skin. Moreover, a residual amount of drug in the skin after ex vivo diffusion was evaluated. The reference ME_R, lecithin-containing ME_L, and gelatin-containing ME_G were characterized in terms of their size, polydispersity index, density, viscosity, electrical conductivity and surface tension. Based on the in vitro diffusion, it can be argued that ME_L slowed down the drug release, while ME_R and ME_G have no significant effect compared to the sample, in which propylene glycol (PG) was used as a solubilizer. Determination of the residual drug amount in the skin after 6 h of the ex vivo permeation was demonstrated as the most valuable method to evaluate the effectiveness of the ME’s application. The results indicate that the most optimal MXD permeation enhancers in alginate gel were the natural surfactants containing MEs. MXD solubilization in ME_G and ME_L had caused more than 5% of the drug remaining in the skin, which is almost a 1.5-fold higher amount compared to the reference gel.

Background: Tretinoin (TRE) is, for its anti-comedogenic and comedolytic activity, widely used in the topical treatment of acne vulgaris. The effect lies in the regulation of sebum production and collagen synthesis. The study is devoted to the formulation of dermal gels containing TRE using microemulsion as the drug solubilizer. Methods: The aim was to evaluate the effect of the reference microemulsion (ME) and lecithin-containing microemulsion (ME_L) on the release of TRE through the synthetic membrane (in vitro) and the pig’s ear skin (ex vivo) through the Franz cell diffusion method. Subsequently, after an ex vivo study, the amount of the drug in the skin influenced by the applied formulation was determined. In addition, the impact of ME on the microscopic structure, texture, and rheological properties of gels was evaluated. Results: On the basis of the analysis of texture, rheological properties, and drug release studies, Carbopol formulations appear to be more appropriate and stable. Considering the synthetic membrane as a stratum corneum, the Carbopol gel penetrated about 2.5-higher amounts of TRE compared to the Xanthan gel. In turn, ex vivo studies suggest that ME_L slows the drug transfer to the dissolution medium, simulating absorption into the blood, which is a desirable effect in local treatment. The drug retention study proved the highest amounts of TRE in the skin to which microemulsion-Carbopol formulations were applied. Conclusion: The results confirm the benefit of TRE solubilization in ME due to its bioavailability from the tested dermal formulations.

This study aimed to prepare and evaluate pellets containing acyclovir as a model drug. Pellets were prepared by the extrusion–spheronization process. Aqueous solutions of natural marine polymers (sodium alginate, chitosan) were compared to semi-synthetic hydroxypropyl methylcellulose (HPMC) in the role of binders. The study focused on the characterization of the pellet properties that are crucial for the formulation of the final dosage form, such as in multi-unit pellet system (MUPS) tablets or hard gelatin capsules filled with the pellets. Finally, the mentioned dosage forms were tested for drug dissolution. The morphology of pellets observed by scanning electron microscopy correlated with the shape evaluation performed by dynamic image analysis. Sodium alginate pellets exhibited the lowest value of sphericity (0.93), and many elongated rods and dumbbells were observed in this batch. Chitosan pellets had the highest value of sphericity (0.97) and were also less rough on the surface. The pellets maintained a constant surface geometry during the dissolution studies; they only reduced in size. The most significant reduction in size and weight was assessed after 2 h of dissolution testing. This fact was in line with the drug release from pellets in capsules or MUPS tablets, which was massive during the first hour, in both cases. The dissolution profiles of all of the batches were comparable.

An important area of interest in pharmaceutical technology is the issue of poorly soluble drugs and their formulation into drug dosage forms that ensure optimal bioavailability. One of the options to solve solubility is the development of nanodispersion systems. This work is focused on the preparation of microemulsion systems suitable for poorly soluble drugs, for example, nimodipine. The composition and structure of microemulsion enable solubilization of different drugs and make it a universal drug carrier. Microemulsions increased the solubility of the model drug 20-fold compared to solubility in water. The use of mucoadhesive polymers – hydroxyethyl cellulose and xanthan gum – improved the in vitro release significantly. The highest amount of nimodipine was released from the microemulsion gel system with hydroxyethyl cellulose (1% w/w) and this depended on the diffusion of dissolved molecules.

The stability of sunscreen formulations is a key factor influencing their protective efficacy and safety, particularly under UV exposure, which can induce photodegradation of UV filters. (1) Background: This study aimed to evaluate the effect of selected antioxidants (stabilized vitamin C, carrot macerate, and ferulic acid) on the sun protection factor (SPF) and photostability of sunscreen formulations. (2) Methods: Four oil-in-water creams with identical compositions, except for the antioxidant type, were prepared and characterized in terms of SPF, rheological behavior, pH, conductivity, stability, and sensory properties. SPF was determined using an in vitro spectrophotometric method before and after UV irradiation (30 and 120 min). (3) Results: Antioxidant incorporation increased initial SPF, with ferulic acid providing the most significant enhancement. After UV exposure, all formulations exhibited a decrease in SPF. However, the formulation containing ferulic acid maintained the highest absolute SPF value, indicating superior photostability. In contrast, vitamin C showed the greatest reduction in SPF, suggesting lower stability under irradiation. Physical characterization confirmed appropriate properties of the formulations, and sensory analysis identified the ferulic acid formulation as the most acceptable. (4) Conclusions: Ferulic acid demonstrated the most favorable impact on sunscreen performance, suggesting its potential as an effective multifunctional ingredient in sunscreens.