Preparation, characterization, and in vitro intestinal permeability evaluation of thalidomide-hydroxypropyl-β-cyclodextrin complexes

Quercetin: A Potential Polydynamic Drug

The study of natural products as potential drug leads has gained tremendous research interest. Quercetin is one of those natural products. It belongs to the family of flavonoids and, more specifically, flavonols. This review summarizes the beneficial pharmaceutical effects of quercetin, such as its anti-cancer, anti-inflammatory, and antimicrobial properties, which are some of the quercetin effects described in this review. Nevertheless, quercetin shows poor bioavailability and low solubility. For this reason, its encapsulation in macromolecules increases its bioavailability and therefore pharmaceutical efficiency. In this review, a brief description of the different forms of encapsulation of quercetin are described, and new ones are proposed. The beneficial effects of applying new pharmaceutical forms of nanotechnology are outlined.

Cholecalciferol complexation with hydroxypropyl-β-cyclodextrin (HPBCD) and its molecular dynamics simulation

The focus of the current study is to investigate cholecalciferol (vitamin D3) solubilization by hydroxypropyl-β-cyclodextrin (HPBCD) complexation through experimental and computational studies. Phase solubility diagram of vitamin D3 (completely insoluble in water) has an A_P profile revealing a deviation from a linear regression with HPBCD concentration increase. Differential scanning calorimetry (DSC) is the best tool to confirm complex formation by disappearance of cholecalciferol exothermic peak in cholecalciferol-HPBCD complex thermogram, due to its amorphous state by entering HPBCD inner hydrophobic cavity, similarly validated by Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). A_P solubility diagram profile can be associated with cholecalciferol-HPBCD complex instability in liquid phase requiring spray drying to bring it to a solid dispersion state (always more stable) illustrated by scanning electron microscopy (SEM). Computational studies led to a deeper understanding and clarification, at molecular level, of the interactions within cholecalciferol-HPBCD complex. Thermodynamics and geometry of the complex were investigated by molecular dynamics (MD) simulation.

Losartan Interactions with 2-Hydroxypropyl-β-CD

Losartan potassium salt (LSR) is a well-known antihypertensive drug with proven beneficial effects on human health. Its formulation with the non-toxic 2-hydroxypropyl-β-cyclodextrin (2-HP-β-CD) could improve its pharmacological profile. Thus, its molecular interactions are studied using a combination of Differential Scanning Calorimetry (DSC), Nuclear Magnetic Resonance (NMR) and Molecular Dynamics (MD). First, its complexation is shown through Differential Scanning Calorimetry as lyophilization provided distinct thermal properties in comparison to the mixture. The complexation is further proved by utilizing the chemical shift changes in the complexation and T1 values. Furthermore, the reversible favorable complexation was shown by MD calculations. Such physical chemical properties provide evidence that this formulation must be further explored through biological experiments.

Inclusion complexation of the anticancer drug pomalidomide with cyclodextrins: fast dissolution and improved solubility

Pomalidomide (POM), a potent anticancer thalidomide analogue was characterized in terms of cyclodextrin complexation to improve its aqueous solubility and maintain its anti-angiogenic activity. The most promising cyclodextrin derivatives were selected by phase-solubility studies. From the investigated nine cyclodextrins - differing in cavity size, nature of substituents, degree of substitution and charge - the highest solubility increase was observed with sulfobutylether-β-cyclodextrin (SBE-β-CD). The inclusion complexation between POM and SBE-β-CD was further characterized with a wide variety of state-of-the-art analytical techniques, such as nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy (IR), circular dichroism spectroscopy, fluorescence spectroscopy as well as X-ray powder diffraction method (XRD). Job plot titration by NMR and the A_L-type phase-solubility diagram indicated 1:1 stoichiometry in a liquid state. Complementary analytical methods were employed for the determination of the stability constant of the complex; the advantages and disadvantages of the different approaches are also discussed. Inclusion complex formation was also assessed by molecular modelling study. Solid state complexation in a 1:1 M ratio was carried out by lyophilization and investigated by IR and XRD. The complex exhibited fast-dissolution with immediate release of POM, when compared to the pure drug at acidic and neutral pH. Kinetic analysis of POM release from lyophilized complex shows that Korsmeyer-Peppas and Weibull model described the best the dissolution kinetics. The cytotoxicity of the complex was tested against the LP-1 human myeloma cell line which revealed that supramolecular interactions did not significantly affect the anti-cancer activity of the drug. Overall, our results suggest that the inclusion complexation of POM with SBE-β-CD could be a promising approach for developing more effective POM formulations with increased solubility.

Differential Scanning Calorimetry (DSC) on Sartan/Cyclodextrin Delivery Formulations

Differential scanning calorimetry (DSC) is a widely utilized method for the interactions of drug molecules with drug delivery systems (DDSs). Herein is described a protocol for studying the interactions and entrapment efficiency of the prototype sartan losartan and the polydynamic, structurally similar irbesartan inside the nontoxic 2-hydroxypropyl-β-cyclodextrin (2-HP-β-CD). The thermal scan properties of both sartan molecules have been studied when physically mixed or complexed with the cyclodextrin. The thermograms indeed showed significant differences between the mixtures and complexes, establishing DSC as a valuable method to characterize the state of the drugs in these pharmaceutical formulations.

Preparation and Biophysical Characterization of Quercetin Inclusion Complexes with β-Cyclodextrin Derivatives to be Formulated as Possible Nose-to-Brain Quercetin Delivery Systems

Quercetin (Que) is a flavonoid associated with high oxygen radical scavenging activity and potential neuroprotective activity against Alzheimer's disease. Que's oral bioavailability is limited by its low water solubility and extended peripheral metabolism; thus, nasal administration may be a promising alternative to achieve effective Que concentrations in the brain. The formation of Que-2-hydroxypropylated-β-cyclodextrin (Que/HP-β-CD) complexes was previously found to increase the molecule's solubility and stability in aqueous media. Que-methyl-β-cyclodextrin (Que/Me-β-CD) inclusion complexes were prepared, characterized, and compared with the Que/HP-β-CD complex using biophysical and computational methods (phase solubility, fluorescence and NMR spectroscopy, differential scanning calorimetry (DSC), and molecular dynamics simulations (MDS)) as candidates for the preparation of nose-to-brain Que's delivery systems. DSC thermograms, NMR, fluorescence spectroscopy, and MDS confirmed the inclusion complex formation of Que with both CDs. Differences between the two preparations were observed regarding their thermodynamic stability and inclusion mode governing the details of molecular interactions. Que's solubility in aqueous media at pH 1.2 and 4.5 was similar and linearly increased with both CD concentrations. At pH 6.8, Que's solubility was higher and positively deviated from linearity in the presence of HP-β-CD more than with Me-β-CD, possibly revealing the presence of more than one HP-β-CD molecule involved in the complex. Overall, water solubility of lyophilized Que/Me-β-CD and Que/HP-β-CD products was approximately 7-40 times and 14-50 times as high as for pure Que at pH 1.2-6.8. In addition, the proof of concept experiment on ex vivo permeation across rabbit nasal mucosa revealed measurable and similar Que permeability profiles with both CDs and negligible permeation of pure Que. These results are quite encouraging for further ex vivo and in vivo evaluation toward nasal administration and nose-to-brain delivery of Que.

Enantioselectivity on the absorption of methylone and pentedrone using Caco-2 cell line: Development and validation of an UHPLC method for cathinones quantification

Synthetic cathinones, such as methylone and pentedrone, are psychoactive derivatives of cathinone, sold in the internet as "plant food" or "bath salts". However, the level at which these compounds and their enantiomers cross the intestinal barrier has not been yet determined. Thus, the present study aimed to analyze the enantioselectivity on the permeability of these drugs through the intestinal barrier by using the Caco-2 cell line, a widely used in vitro model for drug permeability studies. To achieve this goal, an UHPLC-UV method was developed and validated to quantify both synthetic cathinones. The developed UHPLC-UV method revealed high selectivity and a linearity from 1 to 500 μM with correlation coefficients always higher than 0.999. The method has an accuracy that ranged between 89 and 107%, inter-day and intra-day precisions with coefficients of variation below 10%, limits of detection and quantification of 0.31 μM and 0.93 μM for methylone and 0.17 μM and 0.52 μM for pentedrone, respectively. In Caco-2 cells, a differentiated passage of the enantiomers across monolayer was observed for both cathinones. For pentedrone, the difference was observed after the first hour, being R-(-)-pentedrone the most permeable compound. Regarding methylone, the difference was noted after one hour and 30 min, with S-(-)-methylone being the most absorbed enantiomer. In conclusion, a fully validated method was successfully applied for studying the permeability of methylone and pentedrone enantiomers in an in vitro model of human intestine, which allowed to discover, for the first time, the enantioselectivity in drug permeability of this class of drugs.

Discovery and evaluation of novel nitrodihydroimidazooxazoles as promising anti-tuberculosis agents

New analogues of antitubercular drug Delamanid were prepared, seeking drug candidates with enhanced aqueous solubility and high efficacy. The strategy involved replacement of phenoxy linker proximal to the 2-nitroimidazooxazole of Delamanid by piperidine fused 5 or 6-membered ring heterocycles (ring A). The new compounds were all more hydrophilic than Delamanid, and several class of analogues showed remarkable activities against M. bovis. And among these series, the tetrahydro-naphthyridine-linked nitroimidazoles displayed excellent antimycobacterial activity against both replicating (MABA) and nonreplicating (LORA) M. tb H37Rv and low cytotoxicity. Compared to Delamanid, these new compounds (6, 7, 45) demonstrated dramatically improved physicochemical properties and are suitable for further in vitro and in vivo evaluation.

Cyclodextrin⁻Drug Inclusion Complexes: In Vivo and In Vitro Approaches

This review aims to provide a critical review of the biological performance of natural and synthetic substances complexed with cyclodextrins, highlighting: (i) inclusion complexes with cyclodextrins and their biological studies in vitro and in vivo; (ii) Evaluation and comparison of the bioactive efficacy of complexed and non-complexed substances; (iii) Chemical and biological performance tests of inclusion complexes, aimed at the development of new pharmaceutical products. Based on the evidence presented in the review, it is clear that cyclodextrins play a vital role in the development of inclusion complexes which promote improvements in the chemical and biological properties of the complexed active principles, as well as providing improved solubility and aqueous stability. Although the literature shows the importance of their ability to help produce innovative biotechnological substances, we still need more studies to develop and expand their therapeutic properties. It is, therefore, very important to gather together evidence of the effectiveness of inclusion complexes with cyclodextrins in order to facilitate a better understanding of research on this topic and encourage further studies.

Nasal powders of thalidomide for local treatment of nose bleeding in persons affected by hereditary hemorrhagic telangiectasia

In this work nasal powder formulations of thalidomide were designed and studied to be used by persons affected by hereditary hemorrhagic telangiectasia as a complementary anti-epistaxis therapy, with the goal of sustaining the effect obtained with thalidomide oral treatment after its discontinuation for adverse effects. Three nasal powders were prepared using as carriers β-CD or its more hydrophilic derivatives such as hydropropyl-β-CD and sulphobutylether-β-CD and tested with respect to technological and biopharmaceutical features after emission with active and passive nasal powder devices. For all formulated powders, improved dissolution rate was found compared to that of the raw material, making thalidomide promptly available in the nasal environment at a concentration favouring an accumulation in the mucosa. The very limited transmucosal transport measured in vitro suggests a low likelihood of significant systemic absorption. The topical action on bleeding could benefit from the poor absorption and from the fact that about 2-3% of the thalidomide applied on the nasal mucosa was accumulated within the tissue, particularly with the β-CD nasal powder.

Characterization and In Vitro Evaluation of the Complexes of Posaconazole with β- and 2,6-di-O-methyl-β-cyclodextrin

Posaconazole is a triazole antifungal drug that with extremely poor aqueous solubility. Up to now, this drug can be administered via intravenous injection and oral suspension. However, its oral bioavailability is greatly limited by the dissolution rate of the drug. This study aimed to improve water solubility and dissolution of posaconazole through characterizing the inclusion complexes of posaconazole with β-cyclodextrin (β-CD) and 2,6-di-O-methyl-β-cyclodextrin (DM-β-CD). Phase solubility studies were performed to calculate the stability constants in solution. The results of FT-IR, PXRD, ¹H and ROESY 2D NMR, and DSC all verified the formation of the complexes in solid state. The complexes showed remarkably improved water solubility and dissolution rate than pure posaconazole. Especially, the aqueous solubility of the DM-β-CD complex is nine times higher than that of the β-CD complex. Preliminary in vitro antifungal susceptibility tests showed that the two inclusion complexes maintained high antifungal activities. These results indicated that the DM-β-CD complexes have great potential for application in the delivery of poorly water-soluble antifungal agents, such as posaconazole.

Therapeutic potential of thalidomide for gemcitabine-resistant bladder cancer

Controversial effects of thalidomide for solid malignancies have been reported. In the present study, we evaluate the effects of thalidomide for transitional cell carcinoma (TCC), the most common type of bladder cancer. Thalidomide precipitates were observed when its DMSO solution was added to the culture medium. No precipitation was found when thalidomide was dissolved in 45% γ-cyclodextrin, and this concentration of γ-cyclodextrin elicited slight cytotoxicity on TCC BFTC905 and primary human urothelial cells. Thalidomide-γ-cyclodextrin complex exerted a concentration-dependent cytotoxicity in TCC cells, but was relatively less cytotoxic (with IC50 of 200 µM) in BFTC905 cells than the other 3 TCC cell lines, possibly due to upregulation of Bcl-xL and HIF-1α mediated carbonic anhydrase IX, and promotion of quiescence. Gemcitabine-resistant BFTC905 cells were chosen for additional experiments. Thalidomide induced apoptosis through downregulation of survivin and securin. The secretion of VEGF and TNF-α was ameliorated by thalidomide, but they did not affect cell proliferation. Immune-modulating lenalidomide and pomalidomide did not elicit cytotoxicity. In addition, cereblon did not play a role in the thalidomide effect. Oxidative DNA damage was triggered by thalidomide, and anti-oxidants reversed the effect. Thalidomide also inhibited TNF-α induced invasion through inhibition of NF-κB, and downregulation of effectors, ICAM-1 and MMP-9. Thalidomide inhibited the growth of BFTC905 xenograft tumors in SCID mice via induction of DNA damage and suppression of angiogenesis. Higher average body weight, indicating less chachexia, was observed in thalidomide treated group. Sedative effect was observed within one-week of treatment. These pre-clinical results suggest therapeutic potential of thalidomide for gemcitabine-resistant bladder cancer.

Experimental and computational studies of physicochemical properties influence NSAID-cyclodextrin complexation

The objective of this research was to investigate physicochemical properties of an active pharmaceutical ingredient (API) that influence cyclodextrin complexation through experimental and computational studies. Native β-cyclodextrin (B-CD) and two hydroxypropyl derivatives were first evaluated by conventional phase solubility experiments for their ability to complex four poorly water-soluble nonsteroidal anti-inflammatory drugs (NSAIDs). Differential scanning calorimetry was used to confirm complexation. Secondly, molecular modeling was used to estimate Log P and aqueous solubility (S o) of the NSAIDs. Molecular dynamics simulations (MDS) were used to investigate the thermodynamics and geometry of drug-CD cavity docking. NSAID solubility increased linearly with increasing CD concentration for the two CD derivatives (displaying an AL profile), whereas increases in drug solubility were low and plateaued in the B-CD solutions (type B profile). The calculated Log P and S o of the NSAIDs were in good concordance with experimental values reported in the literature. Side chain substitutions on the B-CD moiety did not significantly influence complexation. Explicitly, complexation and the associated solubility increase were mainly dependent on the chemical structure of the NSAID. MDS indicated that each NSAID-CD complex had a distinct geometry. Moreover, complexing energy had a large, stabilizing, and fairly constant hydrophobic component for a given CD across the NSAIDs, while electrostatic and solvation interaction complex energies were quite variable but smaller in magnitude.

Improvement of Physico-mechanical Properties of Partially Amorphous Acetaminophen Developed from Hydroalcoholic Solution Using Spray Drying Technique

OBJECTIVE(S)

This study was performed aiming to investigate the effect of particle engineering via spray drying of hydroalcoholic solution on solid states and physico-mechanical properties of acetaminophen.

MATERIALS AND METHODS

Spray drying of hydroalcoholic solution (25% v/v ethanol/water) of acetaminophen (5% w/v) in the presence of small amounts of polyninylpyrrolidone K30 (PVP) (0, 1.25, 2.5 and 5% w/w based on acetaminophen weight) was carried out. The properties of spray dried particles namely morphology, surface characteristics, particle size, crystallinity, dissolution rate and compactibility were evaluated.

RESULTS

Spray drying process significantly changed the morphology of acetaminophen crystals from acicular (rod shape) to spherical microparticle. Differential scanning calorimetery (DSC) and x-ray powder diffraction (XRPD) studies ruled out any polymorphism in spray dried samples, however, a major reduction in crystallinity up to 65%, especially for those containing 5% w/w PVP was observed. Spray dried acetaminophen particles especially those obtained in the presence of PVP exhibited an obvious improvement of the dissolution and compaction properties. Tablets produced from spray dried samples exhibited excellent crushing strengths and no tendency to cap.

CONCLUSIONS

The findings of this study revealed that spray drying of acetaminophen from hydroalcoholic solution in the presence of small amount of PVP produced partially amorphous particles with improved dissolution and excellent compaction properties.