FTIR Spectroscopic Study of Poly(Ethylene Glycol)–Nifedipine Dispersion Stability in Different Relative Humidities

Bifunctional Carbon Dots-Magnetic and Fluorescent Hybrid Nanoparticles for Diagnostic Applications

There is a huge demand for materials capable of simple detection or separation after conjugation with specific biologic substances when applied as a diagnostic tools. Taking into account the photoluminescence properties of C-dots and the highly magnetic properties of Fe(0), a new hybrid composite of these components was synthesized via ultrasound irradiation. The material was fully characterized by various physicochemical techniques. The main goal of the current study was to obtain a highly magnetic and intense fluorescent hybrid material. The goal was achieved. In addition, magnetic particles tended to agglomerate. The new hybrid can be suspended in ethanol, which is an additional feature of the current research. The dispersion of the hybrid nanoparticles in ethanol was achieved by utilizing the interaction of iron particles with C-dots which were decorated with functional groups on their surface. The newly formed hybrid material has potential applications in diagnostic by conjugating with specific antibodies or with any other biologic compounds. Such application may be useful in detection of various diseases such as: cancer, tuberculosis, etc.

Different BCS Class II Drug-Gelucire Solid Dispersions Prepared by Spray Congealing: Evaluation of Solid State Properties and In Vitro Performances

Delivery of poorly water soluble active pharmaceutical ingredients (APIs) by semi-crystalline solid dispersions prepared by spray congealing in form of microparticles (MPs) is an emerging method to increase their oral bioavailability. In this study, solid dispersions based on hydrophilic Gelucires^® (Gelucire^® 50/13 and Gelucire^® 48/16 in different ratio) of three BCS class II model compounds (carbamazepine, CBZ, tolbutamide, TBM, and cinnarizine, CIN) having different physicochemical properties (logP, pKa, Tm) were produced by spray congealing process. The obtained MPs were investigated in terms of morphology, particles size, drug content, solid state properties, drug-carrier interactions, solubility, and dissolution performances. The solid-state characterization showed that the properties of the incorporated drug had a profound influence on the structure of the obtained solid dispersion: CBZ recrystallized in a different polymorphic form, TBM crystallinity was significantly reduced as a result of specific interactions with the carrier, while smaller crystals were observed in case of CIN. The in vitro tests suggested that the drug solubility was mainly influenced by carrier composition, while the drug dissolution behavior was affected by the API solid state in the MPs after the spray congealing process. Among the tested APIs, TBM-Gelucire dispersions showed the highest enhancement in drug dissolution as a result of the reduced drug crystallinity.

Physical properties and solubility studies of Nifedipine-PEG 1450/HPMCAS-HF solid dispersions

Low-order high-energy nifedipine (NIF) solid dispersions (SDs) were generated by melt solvent amorphization with polyethylene glycol (PEG) 1450 and hypromellose acetate succinate (HPMCAS-HF) to increase NIF solubility while achieving acceptable physical stability. HPMCAS-HF was used as a crystallization inhibitor. Individual formulation components, their physical mixtures (PMs), and SDs were characterized by differential scanning calorimetry, powder X-ray diffraction, and Fourier transform infrared spectroscopy (FTIR). NIF solubility and percent crystallinity (PC) were determined at the initial time and after 5 days stored at 25 °C and 60% RH. FTIR indicated that hydrogen bonding was involved with the amorphization process. FTIR showed that NIF:HPMCAS-HF intermolecular interactions were weaker than NIF:PEG 1450 interactions. NIF:PEG 1450 SD solubilities were significantly higher than their PM counterparts (p < 0.0001). The solubilities of NIF:PEG 1450:HPMCAS-HF SDs were significantly higher than their corresponding NIF:PEG 1450 SDs (p < 0.0001-0.043). All the SD solubilities showed a statistically significant decrease (p < 0.0001) after storage for 5 days. SDs PC were statistically lower than their comparable PMs (p < 0.0001). The PCs of SDs with HPMCAS-HF were significantly lower than SDs not containing only PEG 1450. All SDs exhibited a significant increase in PC (p < 0.0001-0.0089) on storage. Thermogravimetric analysis results showed that HPMCAS-HF bound water at higher temperatures than PEG 1450 (p < 0.0001-0.0039). HPMCAS-HF slowed the crystallization process of SDs, although it did not completely inhibit NIF crystal growth.

In-situ freeze-drying - forming amorphous solids directly within capsules: An investigation of dissolution enhancement for a poorly soluble drug

Conversion into the amorphous form enhances the dissolution of poorly soluble drugs, however the barrier to market for medicines containing an amorphous drug is poor stability. The aim was to produce the amorphous form of a drug within a capsule, without thermal or mechanical stress during manufacture. To facilitate this aim, the mechanism for drug-polymer interaction was explored. Nifedipine and polyvinylpyrrolidone were dissolved in tert-butanol at different drug/polymer ratios. These solutions were dispensed into gelatin capsules and freeze-dried. Differential scanning calorimetry (DSC) & novel FT-IR analysis based on peak symmetry measurements confirmed the absence of crystallinity when polyvinylpyrrolidone exceeded 50%w/w. Capsules containing 10 mg of nifedipine were amorphous and stable for over 3 months at ≈40 °C. Evidence of hydrogen bonding between the N-H group of nifedipine and the C=O group of PVP was observed and this interaction inhibited nifedipine crystallisation. PVP’s high affinity for water and the nifedipine-polymer interaction lead to a significant dissolution rate enhancement. The freeze-dried capsule, 10%w/w nifedipine/PVP, had the highest dissolution rate constant of 0.37 ± 0.05 min⁻¹, and the lowest time to achieve 50% dissolution or t_1/2 of 1.88 ± 0.05 min. This formulation reached 80% dissolved in less than 6 min whereas the equivalent marketed liquid filled nifedipine capsule took 3 times longer to reach 80% dissolution.