Inclusion Complex of Fexofenadine Hydrochloride with Cyclodextrins

<p>Fexofenadine hydrochloride (FFN), (±)-4-[1-hydroxy-4[4-(hydroxydiphenylmethyl)-1-piperidinyl]-butyl] α,α-dimethylbenzeneacetic acid hydrochloride, is a second-generation antihistamine that is used to treat allergies. The drug is highly hydrophobic and slightly soluble in water. Cyclodextrins are widely used to improve the physicochemical and pharmaceutical properties such as solubility, stability, and bioavailability of poorly soluble drug molecules.Cyclodextrins can molecularly encapsulate various drugs into their hydrophobic cavity without forming any covalent bonds. Cyclodextrin (CDs), especially ß-Cyclodextrin (ß-CD), are widely used in the pharmaceutical field due to its ability to stabilize drug molecules and taste masking purposes.<strong> </strong></p><p>The phase solubility study was performed according to the method of Higuchi and Connors by adding the fexofenadine hydrochloride in excess to different concentrations of cyclodextrin solutions. Phase solubility study records show that the stability constant and complex stoichiometry of FFN-CD complexes increases linearly with CD concentration. Also, an increase in the concentration of β-cyclodextrin leads to an increase in the aqueous solubility of FFN. Complexes were analyzed by UV-VIS spectroscopy using the calibration curve of FFN. Also, UV-VIS spectra indicate a bathochromic shift which proves that complex formation has occurred.</p><p>Solid inclusion complexes of fexofenadine/β-cyclodextrin and its derivatives were prepared at the molar ratios of 1:1 by the physical mixing method. Characterization of the complexes was performed by using infrared spectroscopy. </p>

Inclusion Compound of Efavirenz and γ-Cyclodextrin: Solid State Studies and Effect on Solubility

Efavirenz is an antiretroviral drug of widespread use in the management of infections with human immunodeficiency virus type 1 (HIV-1). Efavirenz is also used in paediatrics, but due to its very poor aqueous solubility the liquid formulations available resort to oil-based excipients. In this report we describe the interaction of γ-cyclodextrin with efavirenz in solution and in the solid state. In aqueous solution, the preferential host–guest stoichiometry was determined by the continuous variation method using 1H NMR, which indicated a 3:2 host-to-guest proportion. Following, the solid inclusion compound was prepared at different stoichiometries by co-dissolution and freeze-drying. Solid-state characterisation of the products using FT-IR, 13C{1H} CP-MAS NMR, thermogravimetry, and X-ray powder diffraction has confirmed that the 3:2 stoichiometry is the adequate starting condition to isolate a solid inclusion compound in the pure form. The effect of γ-cyclodextrin on the solubility of efavirenz is studied by the isotherm method.

Cyclodextrin-Efavirenz Complexes Investigated by Solid State and Solubility Studies

This short paper investigates the solubilizing ability of various cyclodextrins with efavirenz as well as the formation of solid inclusion complexes of efavirenz with β-CD and γ-CD. (1) Background: Efavirenz is a non-nucleoside reverse transcriptase inhibitor used as first-line treatment for adult and pediatric human immunodeficiency virus type 1 infection (HIV-1). Belonging to class II of Biopharmaceutical Classification System (BCS), efavirenz is poorly water-soluble. Inclusion into cyclodextrins is a possible strategy for increasing its solubility. (2) Methods: Solubility modulation was investigated by the phase solubility method; inclusion of efavirenz with β- and γ-cyclodextrins was attempted by co-dissolution with co-precipitation; the precipitates were studied by DSC, FT-IR, powder X-ray diffraction and optical microscopy. (3) Results: Solid state analysis of the precipitates shows evidence of separate recrystallization of β-cyclodextrin and efavirenz, whereas in the case of γ-cyclodextrin, a single new phase was observed. (4) Conclusion: Results show that the cavity of β-cyclodextrin is too narrow to accommodate efavirenz and only γ-cyclodextrin, the largest of native cyclodextrins, is able to form a true inclusion complex with this bulky guest.

Comprehensive Characterization of Linalool-HP-β-Cyclodextrin Inclusion Complexes

The objective of the present study is to obtain linalool- cyclodextrin (CDs) solid complexes for possible applications in the food industry. For this purpose, a detailed study of linalool complexation was carried out at different pH values, to optimize the type of CDs and reaction medium that support the highest quantity of encapsulated linalool. Once demonstrated the ability of hydroxypropyl-β-cyclodextrin (HP-β-CDs), to form inclusion complexes with linalool (KC = 921 ± 21 L mol−1) and given their greater complexation efficacy (6.788) at neutral pH, HP-β-CDs were selected to produce solid inclusion complexes by using two different energy sources, ultrasounds and microwave irradiation, subsequently spraying the solutions obtained in the Spray Dryer. To provide scientific solidity to the experimental results, the complexes obtained were characterized by using different instrumental techniques in order to confirm the inclusion of linalool in the HP-β-CDs hydrophobic cavity. The linalool solid complexes obtained were characterized by using 1H nuclear magnetic resonance (1H-NMR) and 2D nuclear magnetic resonance (ROSEY), differential scanning calorimetry, thermogravimetry and Fourier transform infrared spectrometry. Moreover, the structure of the complex obtained were also characterized by molecular modeling.

Boundary Layers in Darcy–Brinkman Flow

Fluid flow in saturated porous media imbedded with a solid inclusion may be described by the Darcy–Brinkman equation. When the Darcy number is small, a boundary-layer theory, similar to Prandtl's theory for viscous flow, is established. The pressure and shear forces are predicted for Darcy–Brinkman flows over a variety of solid inclusions.

Rating the speed of the shearer’s electric motor drive load automatic control

Introduction. It is possible to improve productivity, effectiveness, and cost-efficiency of coal extraction due to the efficient use of physical resources, technical upgrade of mechanized longwall equipment, and introduction of advanced technologies and control methods. The existing method of shearer electric motor drive automation based on the automated load controller of Uran type has a significant drawback of low speed. In case the actuator (A) meets solid rock and the shearer’s (S) speed is not changed, it may result in heavy shock loads on A and its transmission, therefore, increased wear of the cutter or machine’s breakage, leading to production loss due to the reduced speed of travel along the face. The foregoing demands higher standards of the load controller’s speed, making the task of improving the control system’s development a relevant scientific task. Research aim is to synthesize the neural tuner for the coefficients of the proportional-integral controller (PI controller) in the control system of a shearer with increased speed as compared to the existing standard controllers. The research also aims to estimate its efficiency by the method of mathematical simulation. Methodology. Mathematical model has been developed which has made it possible to compare the performance of standard controllers with an adaptive PI controller. The structure and parameters of the neural network underlying the controller have been substantiated. The proposed controller was compared to the standard PI controller and to the MPC controller (microprocessor-based speed controller) by the method of simulation experiment. Research results. The adaptive PI controller has been synthesized based on the neural network which allows changing the coefficients of the PI controller as soon as coal strength changes. Summary. The simulation experiment has shown that the PI controller with the neural network tuner for its coefficients in the control system will make it possible to increase the load controller’s speed by 1.5 to 3 times on average as compared to the classical controller. Therefore, it is going to be possible to avoid critical overload and breakage of mechanical parts in the shearer’s transmission in case of the sudden contact of its actuator with solid inclusion.

Development and Characterization of Orally Disintegrating Tablets Containing a Captopril-Cyclodextrin Complex

Captopril is the first angiotensin I-converting enzyme inhibitor widely used for the treatment of hypertension. Based on the well-known benefits of cyclodextrin inclusion complexes, the present study investigated the ability of β-cyclodextrin to include captopril. Solid inclusion complexes of captopril with β–cyclodextrin in a 1:2 molar ratio were prepared by using the paste method of complexation. For comparison purposes, a simple physical mixture with the same molar ratio was also prepared. Fourier-transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction and simultaneous thermal analysis were used to characterize the raw materials, physical mixture and solid inclusion complex. In order to provide the drug in a more accessible and patient-compliant form following masking its bitter taste, as well as ensuring the appropriate release kinetics, the investigated complex was formulated as orally disintegrating tablets. The study of captopril dissolution in both compendial and simulated saliva media suggested the Noyes Whitney model as the best mathematical model to describe the release phenomena. A clinical study on healthy volunteers also highlighted the taste improvement of the new formulation as compared to conventional tablets.