The production of 3D-printed dosage forms requires the preparation of high-quality filaments containing an active pharmaceutical ingredient (API). The objective of this research is to prepare filaments containing dronedarone hydrochloride, a drug used in the treatment of cardiac arrhythmias. Filaments and 3D-printed tablets were subjected to characterization methods in order to prove and ensure the stability of the API and preservation of the drug content. Blends containing different proportions of dronedarone hydrochloride (DNR), polyethylene glycol (PEG), and polyvinyl alcohol filament (PVA) were prepared in two forms: as a powder mixture and as a solid dispersion. Thermogravimetric analysis was conducted, and the thermal properties of the components and polymer blends were tested using differential scanning calorimetry. Hot melt extrusion at 170 °C was used to prepare the filaments, and the fused deposition modeling technique was employed to print tablets. Drug release profiles were obtained by in vitro tests. The results indicate that the mixture containing 10 wt.% of polyethylene glycol prepared as a solid dispersion exhibits the most straightforward structure and shows only the slightest deviation from the target filament diameter. The compact structure of the tablet obtained from the filament provides a uniform in vitro drug release over a 24-h period. It also shows the smallest aberration from the expected DNR content in the tablet. The paper demonstrates that a blend containing 10 wt.% of PEG, 10 wt.% of DNR, and 80 wt.% of PVA filament is the most appropriate formula for extrusion and tablet printing.