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Photodynamic therapy (PDT) is an emerging treatment modality that utilizes light-sensitive compounds, known as photosensitizers, to produce reactive oxygen species (ROS) that can selectively destroy malignant or diseased tissues upon light activation. This study investigates the incorporation of two porphyrin structures, 5-(4-hydroxy-3-methoxyphenyl)-10,15,20-tris-(4-acetoxy-3-methoxyphenyl) porphyrin (P2.2.) and 5,10,15,20-tetrakis-(4-acetoxy-3-methoxyphenyl) porphyrin (P2.1.), into hydroxypropyl cellulose (HPC) hydrogels for potential use in topical photodynamic therapy (PDT). The structural and compositional properties of the resulting hydrogels were characterized using advanced techniques such as Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), atomic force microscopy (AFM), UV-Visible (UV-Vis) spectroscopy, and fluorescence spectroscopy. FTIR spectra revealed a slight shift of the main characteristic absorption bands corresponding to the porphyrins and their interactions with the HPC matrix, indicating successful incorporation and potential hydrogen bonding. XRD patterns revealed the presence of crystalline domains within the HPC matrix, indicating partial crystallization of the porphyrins dispersed within the amorphous polymer structure. TGA results indicated enhanced thermal stability of the HPC-porphyrin gels compared to 10% HPC gel, with additional weight loss stages corresponding to the thermal degradation of the porphyrins. Rheological analysis showed that the gels exhibited pseudoplastic behavior and thixotropic properties, with minimal impact on the flow properties of HPC by P2.1., but notable changes in viscosity and shear stress with P2.2. incorporation, indicating structural modifications. AFM imaging revealed a homogeneous distribution of porphyrins, and UV-Vis and fluorescence spectroscopy confirmed the retention of their photophysical properties. Pharmacotechnical evaluations showed that the hydrogels possessed suitable mechanical properties, optimal pH, high swelling ratios, and excellent spreadability, making them ideal for topical application. These findings suggest that the porphyrin-incorporated HPC hydrogels have significant potential as effective therapeutic agents for topical applications.

Recent advancements in the formulation of solid dosage forms involving active ingredient-cyclodextrin complexes have garnered considerable attention in pharmaceutical research. While previous studies predominantly focused on incorporating these complexes into solid states, issues regarding incomplete inclusion prompted the exploration of novel methods. In this study, we aimed to develop an innovative approach to integrate liquid-state drug-cyclodextrin inclusion complexes into solid dosage forms. Our investigation centered on rivaroxaban, a hydrophobic compound practically insoluble in water, included in hydroxypropyl-β-cyclodextrin at a 1:1 M ratio, and maintained in a liquid state. To enhance viscosity, hydroxypropyl-cellulose (2 % w/w) was introduced, and the resulting dispersion was sprayed onto the surface of cellulose pellets (CELLETS®780) using a Caleva Mini Coater. The process parameters were meticulously controlled, with atomization air pressure set at 1.1 atm and a fluidizing airflow maintained at 35-45 m 3 /h. Characterization of the coated cellets, alongside raw materials, was conducted using Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) analyses. Physicochemical evaluations affirmed the successful incorporation of rivaroxaban into hydroxypropyl-β-cyclodextrin, with the final cellets demonstrating excellent flowability, compressibility, and adequate hardness. Quantitative analysis via the HPLC-DAD method confirmed a drug loading of 10 mg rivaroxaban/750 mg coated cellets. In vitro dissolution studies were performed in two distinct media: 0.022 M sodium acetate buffer pH 4.5 with 0.2 % sodium dodecyl sulfate (mirroring compendial conditions for 10 mg rivaroxaban tablets), and 0.05 M phosphate buffer pH 6.8 without surfactants, compared to reference capsules and conventional tablet formulations. The experimental capsules exhibited similar release profiles to the commercial product, Xarelto® 10 mg, with enhanced dissolution rates observed within the initial 10 min. This research presents a significant advancement in the development of solid dosage forms incorporating liquid-state drug-cyclodextrin inclusion complexes, offering a promising avenue for improving drug delivery and bioavailability., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)