Solvent effects on infrared spectra of progesterone in CHCl3/cyclo-C6H12 binary solvent systems

In Vitro and Ex Vivo Evaluation of Novel Methacrylated Chitosan-PNIPAAm-Hyaluronic Acid Hydrogels Loaded with Progesterone for Applications in Vaginal Delivery

Miscarriage is defined as the loss of a pregnancy before 24 weeks and administration of progesterone in pregnancy has considerably decreased the risk of premature birth. Progesterone (PGT) starting from the luteal phase stabilizes pregnancy, promotes differentiation of the endometrium, and facilitates the implantation of the embryo. Within the present study, novel hybrid hydrogels based on chitosan methacrylate (CHT), hyaluronic acid (HA), and poly(N-isopropylacrylamide) (PNIPAAm) for vaginal delivery of progesterone were evaluated. The hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) for structural identity assessment and evaluation of their morphological aspects. The ability to swell, the release capacity, enzymatic degradation, cytotoxicity, and mucoadhesion were also reported. The characterized hydrogels demonstrated mucoadhesive properties in contact with the vaginal tissue of swine and bovine origin as substrates, and biodegradability and controlled release in a simulated vaginal environment. Cytocompatibility tests confirmed the ability of the hydrogels and progesterone to support cell viability and growth. The results showed pH-dependent behavior, controlled drug release, good cytocompatibility, and mucoadhesive properties. The hydrogels with higher chitosan amounts demonstrated better bioadhesive properties. This study provides insights into the potential of these hydrogels for the controlled vaginal delivery of progesterone, with promising therapeutic effects and no cytotoxicity observed. The experimental results indicated that a composition with a moderate content of PNIPAAm was suitable for the controlled delivery of progesterone.

Progesterone loaded thermosensitive hydrogel for vaginal application: Formulation and in vitro comparison with commercial product

Progesterone (PGT) is a natural hormone that stimulates and regulates various important functions, such as the preparation of the female body for conception and pregnancy. Due to its low water solubility, it is administered in a micronized form and/or in vehicles with specific solvents requirements. In order to improve the drug solubility, inclusion complexes of PGT and β-cyclodextrins were obtained by the freeze-drying method. Two β-cyclodextrins (native and methylated) in two solvents (water and water:ethanol) and different molar ratio of the reagents were the variables tested for the selection of the best condition for the preparation of the complexes. The PGT/randomly methylated-β-cyclodextrin complexes were incorporated into chitosan thermosensitive hydrogels, as an alternative formulation for the vaginal administration of PGT. Neither the micro and macroscopic characteristics of the gels nor the transition time from solution to gel were modified after the complexes incorporation. In addition, chitosan gels with complexes resisted better the degradation in simulated vaginal fluid in comparison to commercial gel (Crinone®). The chitosan gel with inclusion complexes and Crinone® were tested in vitro in a diffusion assay to evaluate the delivery of the hormone and its diffusion through porcine epithelial mucosa obtained from vaginal tissue. Chitosan gel presented sustained diffusion similar to the exhibited by commercial gel. The use of chitosan gels with inclusion complexes based on cyclodextrins would be a viable alternative for vaginal administration of PGT.

The solvent effects on dimethyl phthalate investigated by FTIR characterization, solvent parameter correlation and DFT computation

This study set out with the aim of investigating the solvent effects on dimethyl phthalate (DMP) using FTIR characterization, solvent parameter correlation and DFT calculation. DMP exposed to 17 organic solvents manifested varying shift in the carbonyl stretching vibration frequency (ν_CO). Non-alkanols induced Band I and alkanols produced Band I and Band II. Through correlating the ν_CO with the empirical solvent scales including acceptor parameter (AN), Schleyer's linear free energy parameter (G), and linear free salvation energy relationships (LSER), Band I was mainly ascribed to non-specific effects from either non-alkanols or alkanol polymers ((alkanol)_n). ν_CO of the latter indicated minor red shift and less variability compared to the former. An assumption was made and validated about the sequestering of hydroxyl group by the bulky hydrophobic chain in (alkanol)_n, creating what we refer to as "screening effects". Ab initio calculation, on the other hand, provided insights for possible hydrogen binding between DMP and (ethanol)_n or between ethanol monomers. The two components of Band I observed in inert solvents were assigned to the two CO groups adopting differentiated conformations. This in turn prompted our consideration that hydrogen binding was highly selective in favor of lowly associated (alkanol)_n and the particular CO group having relatively less steric hindrance and stronger electron-donating capacity. Band II was therefore believed to derive from hydrogen-bond interactions mainly in manner of 1:1 and 1:2 DMP-(alkanol)_n complexes.

Modeling of Progesterone Release from Poly(3-Hydroxybutyrate) (PHB) Membranes

Poly(3-hydroxybutyrate) (PHB) biodegradable polymeric membranes were evaluated as platform for progesterone (Prg)-controlled release. In the design of new drug delivery systems, it is important to understand the mass transport mechanism involved, as well as predict the process kinetics. Drug release experiments were conducted and the experimental results were evaluated using engineering approaches that were extrapolated to the pharmaceutical field by our research group. Membranes were loaded with different Prg concentrations and characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). SEM images showed that membranes have a dense structure before and after the progesterone addition. DSC and FTIR allowed determining the influence of the therapeutic agent in the membrane properties. The in vitro experiments were performed using two different techniques: (A) returning the sample to the receptor solution (constant volume of the delivery medium) and (B) extracting total volume of the receptor solution. In this work, we present a simple and accurate "lumped" second-order kinetic model. This lumped model considers the different mass transport steps involved in drug release systems. The model fits very well the experimental data using any of the two experimental procedures, in the range 0 ≤ t ≤ ∞ or 0 ≤ M t  ≤ M ∞. The drug release analysis using our proposed approaches is relevant for establishing in vitro-in vivo correlations in future tests in animals.

FT-IR study on interactions between medroxyprogesterone acetate and solvent in CHCl₃/cyclo-C6H₁₂ and CCl₄/cyclo-C6H₁₂ binary solvent systems

The intermolecular interactions between medroxyprogesterone acetate (MPA) and CHCl(3) and CCl(4) solvent in CHCl(3)/cyclo-C(6)H(12) and CCl(4)/cyclo-C(6)H(12) binary solvent systems have been studied by Fourier transform infrared spectroscopy (FT-IR). The experimental results showed that there are hydrogen bonding interactions between oxygen atoms of all carbonyl groups in MPA and hydrogen atom of CHCl(3) so as to form 1:3 complex of MPA with CHCl(3) and produce three new absorption bands at 1728.9-1736.1, 1712.7-1717.4 and 1661.9-1673.8 cm(-1), respectively. And, 1:1 complex of MPA with CCl(4) is formed in CCl(4)/cyclo-C(6)H(12) binary solvent as a result of hydrogen bonding interaction between C3 carbonyl group and empty d-orbital in chlorine atom of CCl(4) leading to producing new absorption band at 1673.2-1674.2 cm(-1). However, all free carbonyl and associated carbonyl stretching vibrations of MPA in CHCl(3)/cyclo-C(6)H(12) and CCl(4)/cyclo-C(6)H(12) binary solvent systems shift to lower wavenumbers with the increasing of volume fraction of CHCl(3) and CCl(4) in binary solvent systems owing to the dipole-dipole interaction and the dipole-induced dipole interaction between MPA and solvents.

FT-IR spectroscopy and DFT calculation study on the solvent effects of benzaldehyde in organic solvents

FT-IR spectra of benzaldehyde in 11 different organic solvents were recorded and analyzed. The density functional theory (DFT) B3LYP/6-31G* method was chosen to calculate the infrared spectrum of benzaldehyde in gaseous state. The electrostatic effects of different solvents in benzaldehyde solutions were calculated using DFT with the self-consistent isodensity polarizable continuum model (SCI-PCM). Two remarkable carbonyl (C=O) peaks of benzaldehyde were observed by FT-IR in alcohol solvents, which were caused by different hydrogen bond species and explained by ab initio calculation. The results showed that the combination of SCI-PCM model and ab initio calculation could give excellent agreements with FT-IR spectra of title compound in solutions.