Most novel active pharmaceutical ingredients have low water solubility; therefore, solubility-enhancing methods are applied. The aim of the present investigation is to study the impact of nine commonly used pharmaceutical excipients (fillers, surfactants, cyclodextrins, polymers) on solubility, permeability and their relationship. This is crucial for ensuring optimal bioavailability. Carbamazepine, naproxen and pimobendan were chosen as model compounds due to their different acid–base properties. Equilibrium solubility was measured by the traditional shake flask method. Effective permeability was determined by the PAMPA model. Measurements of ionizable compounds were carried out at three pH values. The pH-dependent change in the investigated parameters is maintained even in the presence of excipients. Fillers resulted in a slight or no effect, while the impact of other excipients showed a significant concentration dependence. The impact of excipients was influenced by the structure and ionization state of the molecules. The dominance of the ionized form moderates the impact of excipients. The changes in solubility were more pronounced than in the case of permeability. By examining the effect of the ionization state and interactions with excipients, this work supports the development of formulations that enhance solubility with minimal impacts on permeability. Additionally, it can serve as good basis for preformulation studies and design optimization.

The bioavailability of a drug is closely linked to its solubility, making its early determination essential in drug development. The saturation shake-flask (SSF) method is the gold standard protocol for this, which includes a phase separation step—either by sedimentation, filtration, or centrifugation. This step is critical, as it can directly influence the accuracy of the results. This study investigated the impact of centrifugation parameters—time and rotation speed—on solubility measurements. Additionally, we compared two sample preparation protocols: continuous stirring for 24 h versus 6 h of stirring followed by 18 h of sedimentation before centrifugation. Four model compounds were tested at three pH values using Britton–Robinson buffers. Centrifugation was conducted for 5, 10, or 20 min at either 5000 or 10,000 rpm. Results showed that pre-sedimented samples yielded solubility values closer to sedimentation-only references, while continuous stirring often led to overestimated values, particularly at higher speeds and longer durations. One such example was papaverine hydrochloride, that showed solubility values 60–70% higher than the reference after centrifugation at 10,000 rpm for 20 min without prior sedimentation. Lower standard deviations were observed with shorter, slower centrifugation, with 5 min and 5000 rpm yielding results closest to the reference values.

Background/Objectives: The growing demand for personalised, patient-centric drug delivery systems has driven innovation in pharmaceutical manufacturing, particularly in multi-unit particulate systems (MUPS). Methods: In this study, inert cores with tailor-made geometry for multi-particulate formulations were fabricated with high-resolution stereolithography (SLA) 3D printing. By a printable photopolymer resin, dimensionally accurate and mechanically robust starter cores were produced. The additively manufactured inert subunits were drug-layered with ibuprofen sodium using a fluidised bed process. Then, a controlled-release film coating of Eudragit RS 30D was applied with varying coating thicknesses. The initial 3D-printed subunits, together with the drug-layered and finally film-coated microparticles, were characterised by image analysis, Raman microspectroscopic measurements, and official methods of the European Pharmacopoeia. Results: The combined approach of 3D printing and traditional pharmaceutical processing proved highly effective. The 3D-printed cores demonstrated both flexibility in design and consistency in performance. Conclusions: These findings highlight the feasibility of using 3D printing to produce patient-specific, functional cores in multi-particulate systems that can be easily modified according to the patient’s needs. The fabricated minitablets can be used as alternatives to widely used inert cores. Integrating additive manufacturing with conventional coating techniques offers promising new avenues for developing next-generation, personalised drug delivery solutions.

Introduction: The objective of this study was to evaluate the efficacy of a nanofabricated formulation of gonadotropin-releasing hormone analogue, buserelin acetate (GnRH-BA), conjugated with chitosan nanoparticles (CH-NPs) as a nanocarrier. The resulting nano-GnRH-BA formulation was incorporated into the Ovsynch (OVS) protocol at a 50% reduced dose to improve ovulation synchronization and reproductive performance in dairy heifers. Methods: CH-NPs and nano-GnRH-BA were synthesized via the ionic gelation method. Key characteristics, including particle shape, size, Polydispersity Index (PdI), and drug-loading efficiency (DLE%), were evaluated. A total of 210 Holstein-Friesian heifers were assigned to either a standard OVS ( n = 82) or nano-OVS ( n = 128) protocol. Ovarian dynamics were monitored on days 0 (baseline), 9 (before the second GnRH administration), and 27 post-inseminations (post-AI) during the protocol. Reproductive parameters, including estrus induction rate (EIR), first conception rate (FCR), and pregnancy loss (PL), were also recorded. Additionally, the association between ovarian activity and FCR was analyzed. Results: Baseline ovarian activity (day 0) was similar between groups. By day 9, heifers subjected to nano-OVS exhibited improved follicular development, with larger preovulatory follicles (18.9 ± 1.4 mm) than those subjected to the standard OVS group (16.8 ± 1.3 mm; P = 0.007). On day 27 post-AI, larger corpora lutea were observed in the nano-OVS group compared with the standard OVS group (21.3 ± 1.3 mm vs. 18.3 ± 1.4 mm, respectively; P = 0.04). These findings were associated with higher EIR (78.6%, P = 0.03) and FCR (47.7%, P = 0.32), and lower PL (13.1%, P = 0.01) compared to the standard protocol (65.9%, 47.7%, and 21.2%, respectively). Correlation analysis exhibited different physiological patterns between groups. Discussion: Nanofabrication of GnRH may enhance hormone stability and enable sustained release, thereby improving ovulation synchronization and luteal development. Conclusion: Overall, the nano-GnRH-BA formulation within the OVS protocol resulted in a 50% reduction without compromising fertility, while also improving ovarian function and reducing PL in dairy heifers. This approach may represent a promising alternative to conventional synchronization strategies.