Achievement of pH-independence of poorly-soluble, ionizable loratadine by inclusion complex formation with dimethyl-β-cyclodextrin

Incorporation of Loratadine-Cyclodextrin Complexes in Oral Thin Films for Rapid Drug Delivery

Rapidly dissolving polymer thin films, or oral thin films (OTFs), have recently emerged as an improved oral drug delivery vehicle with its ability to bypass liver first pass metabolism, longer shelf-life, and simpler transport and distribution requirements, compared to traditional tablets and liquid formulations. Loratadine (LOR), an antihistamine commonly used to treat allergic rhinitis, undergoes liver first pass metabolism and is a prime candidate for incorporation within an OTF. However, loratadine is a BCS II drug with low aqueous solubility. Herein, the solubility of loratadine was improved by complexation with methyl β-cyclodextrin (MBCD) by co-evaporation of 2:1, 1:1, and 1:2 LOR:MBCD ratios and incorporation into a pullulan-based OTF at 4 wt% by solvent casting at 50 °C for 30 - 35 min. A therapeutically relevant 10 mg LOR dose could be prepared in a 3 cm by 3 cm OTF. The feasibility of complexation was observed with a Bs-type phase solubility diagram, and complexation itself was confirmed via differential scanning calorimetry (DSC) by disappearance of the LOR melting peak, Fourier-transform infrared spectroscopy (FTIR) by shifting of the C=O peak, via 1H NMR spectroscopy by downfield shifting and change in peak multiplicity of the LOR aromatic protons, and via diffusion-ordered spectroscopy by a decrease in the diffusion coefficient of LOR:MBCD complex. LOR:MBCD could be incorporated homogeneously throughout an OTF, and LOR:MBCD OTFs exhibited reasonable mechanical strength and endured 12 ± 3 folds before breaking. LOR:MBCD OTFs disintegrated within 38 ± 10 s. The cumulative in vitro release of LOR:MBCD OTFs peaked at 80 % within 3-4 min of dissolution, and LOR in LOR:MBCD OTFs exhibited permeability across a 0.22 μm nitrocellulose membrane, demonstrating its applicability as a rapid drug delivery vehicle.

Design and characterization of loratadine nanosuspension prepared by ultrasonic-assisted precipitation

Nanoparticle engineering is a well-defined technique employed as a novel and effective method in drug design and delivery. It is widely used to control particle size, as well as the morphological and physicochemical properties of active pharmaceutical ingredients. Furthermore, it serves as a method of pre-dispersion preparation for various dosage form developments. Nanotechnology produces nanomaterials with enhanced properties in terms of solubility, dissolution and permeability. In this work, ultrasonic-assisted precipitation was employed to produce nanosuspensions of poorly water-soluble loratadine, using different stabilizers. The objective of our study was attempting to prepare solid nanoparticles of loratadine to be used as a possible intermediate for designing various dosage forms. The effects of the type(s) and concentration(s) of stabilizer(s) on mean particle size were assessed. Optimal process parameters required to produce homogeneous nanoparticles with particle size below 500 nm and polydispersity less than 0.3 were determined both for precipitation and ultrasonication. Pre-dispersions were evaluated for their particle size, polydispersity index and zeta potential. Freeze-drying was employed to produce dry nanoparticles. Particle size, particle size distribution and zeta potential of the dried nanoparticles were measured after reconstitution in water. Besides thermal analysis using DSC and structural analyses (XRPD and FT-IR), the morphological characteristics and dissolution behaviors were also investigated. The selected freeze-dried nanoparticles had a mean particle size range of 353-441 nm, a polydispersity index ranging between 0.167 and 0.229 and a zeta potential between -25.7 and -20.7 mV. These results suggest that material and process parameters were successfully optimized. DSC and XRPD spectra confirmed interactions between the formulation's components during freeze-drying. The solid nanoparticles showed 30-42% of cumulative release after 10 min compared to less than 1% of dissolution characterizing loratadine without pre-processing. This study demonstrates that preparing dried loratadine nanoparticles suitable for designing effective drug preparations is a feasible approach.

Theoretical and Experimental Studies on Inclusion Complexes of Pinostrobin and β-Cyclodextrins

Pinostrobin (PNS) belongs to the flavanone subclass of flavonoids which shows several biological activities such as anti-inflammatory, anti-cancerogenic, anti-viral and anti-oxidative effects. Similar to other flavonoids, PNS has a quite low water solubility. The purpose of this work is to improve the solubility and the biological activities of PNS by forming inclusion complexes with β-cyclodextrin (βCD) and its derivatives, heptakis-(2,6-di-O-methyl)-β-cyclodextrin (2,6-DMβCD) and (2-hydroxypropyl)-β-cyclodextrin (HPβCD). The A_L-type diagram of the phase solubility studies of PNS exhibited the formed inclusion complexes with the 1:1 molar ratio. Inclusion complexes were prepared by the freeze-drying method and were characterized by differential scanning calorimetry (DSC). Two-dimensional nuclear magnetic resonance (2D-NMR) and steered molecular dynamics (SMD) simulation revealed two different binding modes of PNS, i.e., its phenyl- (P-PNS) and chromone- (C-PNS) rings preferably inserted into the cavity of βCD derivatives whilst only one orientation of PNS, where the C-PNS ring is inside the cavity, was detected in the case of the parental βCD. All PNS/βCDs complexes had a higher dissolution rate than free PNS. Both PNS and its complexes significantly exerted a lowering effect on the IL-6 secretion in LPS-stimulated macrophages and showed a moderate cytotoxic effect against MCF-7 and HeLa cancer cell lines in vitro.

A new polymorphic form and polymorphic transformation of loratadine

In this work, a new form of loratadine (Form B) was prepared from a 20% methanol and 80% water mixture and characterized by polarizing microscopy, scanning electron microscopy, powder X-ray diffraction and differential scanning calorimetry.

Solidified SNEDDS of loratadine: formulation using hydrophilic and hydrophobic grades of Aerosil®, pharmacokinetic evaluations and in vivo–in silico predictions using GastroPlus™

Hydrophilic and hydrophobic grades of Aerosil® were employed to develop solid-SNEDDS of loratadine and evaluated for their influence on powder, physicochemical and biopharmaceutical properties.

Dissolution evaluation in vitro and bioavailability in vivo of self-microemulsifying drug delivery systems for pH-sensitive drug loratadine

The aim of this study was to improve the oral absorption of loratadine, a pH-sensitive drug, by self-microemulsifying drug delivery systems (SMEDDSs). The optimal SMEDDS was analysed and evaluated after emulsification in distilled water with diameter of 26.57 ± 0.71 nm and zeta potential of -30.5 ± 4.5 mV. Dissolution experiments in vitro were carried out in different released media of pH values and the SMEDDS formulations were able to release loratadine completely in different media while market tablets just performed similarly in the media of pH 1.2. Furthermore, the oral bioavailability and the pharmacokinetic behaviour of loratadine formulations in vivo were studied after a single dose of 1 mg/kg loratadine in beagle dogs. The SMEDDS formulations displayed higher Cmax and AUC, approximately 9 and 5 times increase than those of market tablets (p < 0.01) respectively. These results demonstrated that SMEDDS formulations had significantly increased the oral absorption of loratadine in beagle dogs.

Spray-dried voriconazole-cyclodextrin complexes: solubility, dissolution rate and chemical stability

The present work investigates the effect of complexation with hydroxypropyl-beta-cyclodextrin (HPBCD) and 2-O-methyl-beta-cyclodextrin (2-O-MBCD), on voriconazole solubility, dissolution rate and chemical stability. Drug-cyclodextrin complexes were prepared as aqueous solutions, which were spray-dried, and their properties were compared to wet ground samples and physical mixtures. DSC analysis revealed absence of crystalline voriconazole from spray-dried complexes. FTIR spectroscopy indicated changes in the H-bonding network of the hydroxyl groups of cyclodextrin following drug inclusion. Dissolution rate of voriconazole was significantly higher from spray-dried complexes with either cyclodextrin in comparison with free drug, physical mixtures, or wet ground mixtures. However, two degradation impurities were found in aged samples, with slightly higher impurity level with HPBCD. Performed solubility studies suggested that 2-O-MBCD is more efficient solubilizer. Molecular docking simulations showed a difference in the 1:1 binding affinities and sites, with HPBCD surprisingly forming complexes of much lower energy, thus suggesting a multiple rather than a 1:1 complexation.

Improvement of aripiprazole solubility by complexation with (2-hydroxy)propyl-β-cyclodextrin using spray drying technique

Due to the fact that the number of new poorly soluble active pharmaceutical ingredients is increasing, it is important to investigate the possibilities of improvement of their solubility in order to obtain a final pharmaceutical formulation with enhanced bioavailability. One of the strategies to increase drug solubility is the inclusion of the APIs in cyclodextrins. The aim of this study was to investigate the possibility of aripiprazole solubility improvement by inclusion in (2-hydroxy)propyl-β-cyclodextrin (HPBCD) and simultaneous manipulation of pH of the medium and addition of polyvinylpyrrolidone. Aripiprazole-HPBCD complexes were prepared by spray drying aqueous drug-HPBCD solutions, and their properties were compared with those prepared by solvent-drop co-grinding and physical mixing. The obtained powders were characterized by thermoanalytical methods (TGA and DSC), FTIR spectroscopy, their dissolution properties were assessed, while the binding of aripiprazole into the cavity of HPBCD was studied by molecular docking simulations. The solubilization capacity was found to be dependent on pH as well as the buffer solution's ionic composition. The presence of PVP in the formulation could affect the solubilization capacity significantly, but further experimentation is required before its effect is fully understood. On the basis of solubility studies, the drug/HPBCD stoichiometry was found to be 1:3. The spray-dried products were free of crystalline aripiprazole, they possessed higher solubility and dissolution rate, and were stable enough over a prolonged period of storage. Spray drying of cyclodextrin solutions proved to be an appropriate and efficient technique for the preparation of highly soluble inclusion compounds of aripiprazole and HPBCD.

Curve-fitting FTIR studies of loratadine/hydroxypropyl-beta-cyclodextrin inclusion complex induced by co-grinding process

The formation steps of inclusion complex caused by co-grinding loratadine (LOR) and hydroxypropyl-beta-cyclodextrin (HP-beta-CD) with a molar ratio of 1:1 or 1:2 were quantitatively investigated by Fourier transform infrared (FTIR) spectroscopy with curve-fitting analysis and differential scanning calorimetry (DSC). The phase solubility study and the co-evaporated solid products of the mixture of LOR and HP-beta-CD were also examined. The result indicates that the aqueous solubility of LOR was linearly increased with the increase of HP-beta-CD concentrations, in which the phase solubility diagram was classified as A(L) type. The higher apparent stability constant (2.22 x 10(4)M(-1)) reveals that the inclusion complex formed between LOR and HP-beta-CD was quite stable. The endothermic peak at 134.6 degrees C for the melting point of LOR gradually disappeared from DSC curves of LOR/HP-beta-CD coground mixtures by increasing the cogrinding time, as the disappearance of the co-evaporated solid products. The disappearance of this endothermic peak from LOR/HP-beta-CD coground mixture or the co-evaporated solid products was due to the inclusion complex formation between LOR and HP-beta-CD after cogrinding process or evaporation. Moreover, IR peaks at 1676 cm(-1) down-shifted from 1703 cm(-1) (CO stretching) and at 1235 cm(-1) upper-shifted from 1227 cm(-1) (C-O stretching) related to LOR in the inclusion complex were observed with the increase of cogrinding time, but the peak at 1646 cm(-1) due to O-H stretching of HP-beta-CD was shifted to 1640 cm(-1). The IR spectrum of 15 min-coground mixture was the same as the IR spectrum of the co-evaporated solid product, strongly indicating that the grinding process could cause the inclusion complex formation between LOR and HP-beta-CD. Three components (1700, 1676, and 1640 cm(-1)) and their compositions were certainly obtained in the 1740-1600 cm(-1) region of FTIR spectra for the LOR/HP-beta-CD coground mixture and the co-evaporated solid products by curve-fitting analysis. The component of 1700 cm(-1) detected was due to the un-included LOR in the inclusion complex. This implies that FTIR spectroscopy with curve-fitting analysis might be useful for discriminating the components and compositions in the inclusion complex.