Influence of betacyclodextrin on the release of poorly soluble drugs from inert and hydrophilic heterogeneous polymeric matrices

Controlled release of enrofloxacin by vanillin-crosslinked chitosan-polyvinyl alcohol blends

In transdermal drug delivery applications uniform drug distribution and sustained release are of great importance to decrease the side effects. In this direction in the present research, vanillin crosslinked chitosan (CS) and polyvinyl alcohol (PVA) blend based matrix-type transdermal system was prepared by casting and drying of aqueous solutions for local delivery of enrofloxacin (ENR) drug. Subsequently, the properties including the morphology, chemical structure, thermal behavior, tensile strength, crosslinking degree, weight uniformity, thickness, swelling and drug release of the CS-PVA blend films before and after crosslinking were characterized. In vitro drug release profiles showed the sustained release of ENR by the incorporation of vanillin as a crosslinker into the CS-PVA polymer matrix. Furthermore, the release kinetic profiles revealed that the followed mechanism for all samples was Higuchi and the increase of vanillin concentration in the blend films resulted in the change of diffusion mechanism from anomalous transport to Fickian diffusion. Overall, the obtained results suggest that the investigated vanillin crosslinked CS-PVA matrix-type films are potential candidates for transdermal drug delivery system.

Chitosan and β-Cyclodextrin-epichlorohydrin Polymer Composite Film as a Plant Healthcare Material for Carbendazim-Controlled Release to Protect Rape against Sclerotinia sclerotiorum (Lib.) de Bary

The influence of β-cyclodextrin-epichlorohydrin (β-CD-EP) polymers on the improvement of the solubility and antifungal activity of carbendazim has been investigated. Meanwhile, the potential of the chitosan and β-CD-EP composite film used as a plant healthcare material for carbendazim-controlled release to protect rape against Sclerotinia sclerotiorum (Lib.) de Bary has been evaluated. β-CD-EP-1 and 2 (β-CD content, 750 mg/g and 440 mg/g, respectively) were found to significantly improve the solubility of the guest molecule carbendazim (17.9 and 18.5 times, respectively) and the 1:1 stoichiometry of the host-guest was confirmed by the Job's plot. A slight synergism was observed for the β-CD-EP/carbendazim complex against S. sclerotiorum (Lib.) de Bary, indicating an enhancement to the bioavailability of carbendazim. The in vitro release studies revealed that β-CD-EP polymers could efficiently modulate carbendazim release behaviors, such as the release retard and rate. The in vivo efficacy experiments demonstrated that the β-CD-EP/carbendazim and chitosan composite film could significantly prolong the effective duration of carbendazim at a concentration of 100 μg/mL compared with spraying carbendazim at 500 μg/mL. Thereby, a highly useful and strategic concept in plant disease control by a plant healthcare material-the chitosan and polymeric β-CD-EP composite film-is provided, which could also serve as a concept for related plant diseases.

Hybrid polymeric matrices for oral modified release of Desvenlafaxine succinate tablets

Purpose: Desvenlafaxine succinate (DSV) is a water soluble anti-depressant drug, which is rapidly absorbed after oral administration exaggerating its side effects. The current work aimed to prepare controllable release DSV matrix to reduce DSV side effects related to its initial burst. Methods: Fifteen DSV matrix formulations were prepared using different polymers, polymer/drug ratios and matrix excipients and characterized using Differential Scanning Calorimetry (DSC), infrared (IR) spectroscopy, water uptake and in vitro DSV release. The release kinetics were calculated to determine the drug release mechanism. Ex-vivo DSV absorption via rat intestinal mucosal cells and the calculation of the apparent permeability coefficient (P_app) were performed using everted sac technique. Results: Maltodextrin was the best matrix excipient (F7 and F10) showing acceptable decrease in the initial burst compared to the innovator. The addition of negatively charged polymers sodium carboxy methyl cellulose (SCMC) or sodium alginate resulted in an interaction that was proved by DSC and IR findings. This interaction slowed DSV release. F10 showed an excellent absorption of more than 80% of DSV after 4 h and the highest similarity factor with the innovator (84.7). Conclusion: A controllable release pattern of DSV was achieved using Methocel, Maltodextrin and SCMC. The obtained results could be used as a platform to control the release of cationic water soluble drugs that suffer from side effects associated with their initial burst after oral administration.

Evaluation of hot-melt extrusion technique in the preparation of HPC matrices for prolonged release

The aim of the work was to explore the potential of hot-melt extrusion (HME) for preparing hydroxypropyl cellulose (HPC)-based prolonged-release matrices intended for oral administration. For this purpose, compressed and extruded systems, either composed of polymer only or containing different amounts of a model drug (theophylline or ketoprofen), were compared. The overall morphological/physical changes of the systems following interaction with water indicated that the manufacturing process would not exert a major influence on the swelling behavior of the polymeric matrices. On the other hand, the release rate was generally higher from HME systems probably due to an increase of the drug dissolution rate, which is in agreement with the relevant DSC data (loss of drug cristallinity). However, the technological characteristics of the matrices and the maximum drug load were demonstrated to depend on the mode of interaction of the active ingredient with the molten polymer. In this respect, the formation of a composite material from ketoprofen and HPC, when mixed in specific ratios, was supposed to explain the differences observed between compressed and extruded systems in terms of morphological characteristics, hydration/swelling and release. The obtained results support the possibility of exploiting the advantages offered by HME technique, above all the potential for continuous manufacturing, in the preparation of prolonged-release swellable matrices based on a cellulose derivative.

Thermally triggered mucoadhesive in situ gel of loratadine: β-cyclodextrin complex for nasal delivery

The aim of the present study was to increase the solubility of an anti-allergic drug loratadine by making its inclusion complex with β-cyclodextrin and to develop it's thermally triggered mucoadhesive in situ nasal gel so as to overcome first-pass effect and consequently enhance its bioavailability. A total of eight formulations were prepared by cold method and optimized by 2(3) full factorial design. Independent variables (concentration of poloxamer 407, concentration of carbopol 934 P, and pure drug or its inclusion complex) were optimized in order to achieve desired gelling temperature with sufficient mucoadhesive strength and maximum permeation across experimental nasal membrane. The design was validated by extra design checkpoint formulation (F9) and Pareto charts were used to help eliminate terms that did not have a statistically significant effect. The response surface plots and possible interactions between independent variables were analyzed using Design Expert Software 8.0.2 (Stat Ease, Inc., USA). Faster drug permeation with zero-order kinetics and target flux was achieved with formulation containing drug: β-cyclodextrin complex rather than those made with free drug. The optimized formulation (F8) with a gelling temperature of 28.6±0.47°C and highest mucoadhesive strength of 7,676.0±0.97 dyn/cm2 displayed 97.74±0.87% cumulative drug permeation at 6 h. It was stable for over 3 months and histological examination revealed no remarkable damage to the nasal tissue.

Molecular cycloencapsulation augments solubility and improves therapeutic index of brominated noscapine in prostate cancer cells

We have previously shown that a novel microtubule-modulating noscapinoid, EM011 (9-Br-Nos), displays potent anticancer activity by inhibition of cellular proliferation and induction of apoptosis in prostate cancer cells and preclinical mice models. However, physicochemical and cellular barriers encumber the development of viable formulations for future clinical translation. To circumvent these limitations, we have synthesized EM011-cyclodextrin inclusion complexes to improve solubility and enhance therapeutic index of EM011. Phase solubility analysis indicated that EM011 formed a 1:1 stoichiometric complex with β-CD and methyl-β-CD, with a stability constant (K(c)) of 2.42 × 10(-3) M and 4.85 × 10(-3) M, respectively. Fourier transform infrared spectroscopy suggested the penetrance of either a O-CH(2) or OCH(3)-C(6)H(4)-OCH(3) moiety of EM011 in the β-CD or methyl-β-CD cavity. In addition, multifarious techniques, namely, differential scanning calorimetry, powder X-ray diffraction, scanning electron microscopy, NMR spectroscopy, and computational studies validated the cage complex of EM011 with β-CD and methyl-β-CD. Moreover, rotating frame overhauser enhancement spectroscopy showed that the H(a) proton of the OCH(3)-C(6)H(4)-OCH(3) moiety was in close proximity with H3 proton of the β-CD or methyl-β-CD cavity. Furthermore, we found that the solubility of EM011 in phosphate buffer saline (pH 7.4) was enhanced by ~11 fold and ~21 fold upon complexation with β-CD and methyl-β-CD, respectively. The enhanced dissolution of the drug CD-complexes in aqueous phase remarkably decreased their IC(50) to 28.5 μM (9-Br-Nos-β-CD) and 12.5 μM (9-Br-Nos-methyl-β-CD) in PC-3 cells compared to free EM011 (~200 μM). This is the first report to demonstrate the novel construction of cylcodextrin-based nanosupramolecular vehicles for enhanced delivery of EM011 that warrants in vivo evaluation for the superior management of prostate cancer.

Influence of soluble and insoluble cyclodextrin polymers on drug release from hydroxypropyl methylcellulose tablets

BACKGROUND

The influence of beta-cyclodextrin (beta-CD) polymers on drug release from hydroxypropyl methylcellulose (HPMC) matrices has not been reported in the literature.

AIM

The influence of monomeric beta-CD and both soluble and insoluble beta-CD polymers on drug release from tablets containing either 30% or 50% hydroxypropyl methylcellulose has been studied using diflunisal (DF) as model drug.

METHOD

The DF-beta-CD inclusion complex (1:1 M) was prepared by coevaporation and characterised using X-ray diffraction, differential thermal analysis, and IR spectroscopy. The dissolution assays were performed according to the USP paddle method.

RESULTS

The incorporation of beta-CD in the complexed form increases drug release from hydroxypropyl methylcellulose tablets in comparison with the physical mixture because of the better solubilization of the drug. The soluble polymer promotes drug release to a higher extent than the physical mixture with monomeric beta-CD, but the insoluble polymer, which is itself a hydrogel, gives rise to the most retarded release profile, probably by retention of the drug in its structure. The formulations containing physical mixtures with either beta-CD or the soluble polymer present an optimum adjustment to zero-order release kinetics, and the inclusion complex followed non-Fickian diffusion according to the Korsmeyer-Peppas model.

CONCLUSION

The release profile of DF from a HPMC matrix can be modulated in different ways by the use of either monomeric or polymeric beta-CD.

Modulation of release rate and barrier transport of Diclofenac incorporated in hydrophilic matrices: role of cyclodextrins and implications in oral drug delivery

The aim of this work was to investigate how the incorporation of a hydrophilic cyclodextrin (CD) inside erodible hydrophilic matrices affects drug-release behavior and transport properties through artificial and biological membranes. To this purpose, Diclofenac (Dic) was incorporated in poly(ethyleneoxide) (PEO) matrices as poorly soluble free acid (DicH) or freely water-soluble sodium salt (DicNa) in the presence or absence of hydroxypropyl-beta-cyclodextrin (HP beta CD). Preliminary experiments demonstrated that HP beta CD increased Dic apparent solubility as a function of its amount in the solution and medium pH due to complex formation. Permeation of ionized Dic through porcine buccal mucosa gave higher values of J(SS) and K(p) as compared to silicon membranes and depended on the presence of HP beta CD. Incorporation of HP beta CD in PEO tablets resulted in an increase of release rate for both forms of Dic whereas cumulative drug flux through silicon membranes and porcine buccal mucosa was increased for DicH and decreased for DicNa. An interpretation of this behavior was attempted on the basis of the presence of a transport resistance occurring inside the hydrated gel matrix as modified by the presence of CD. In conclusion, this study has demonstrated that the use of CDs in hydrophilic matrices intended for oral drug delivery should be rationalized since their modulator effect relies not only on drug-dissolution rate but also on environment where drug release occurs (aqueous medium, membrane interface).

The utility of cyclodextrins for enhancing oral bioavailability

Cyclodextrins (CD) have been utilized extensively in pharmaceutical formulations to enhance oral bioavailability. A critical review of the literature in which cyclodextrins were utilized for this purpose was conducted. The goal of this review was to determine if quantitative guidelines for drug and cyclodextrin properties necessary for bioavailability enhancement using cyclodextrins could be extracted. Twenty-eight studies were examined in which the focus was on the use of cyclodextrins as solubilizers to enhance bioavailability. Commonly observed factors included: utilization of pre-formed complex rather than physical mixtures, drug hydrophobicity (logP > 2.5), low drug solubility (typically< 1 mg/ml), moderate binding constant (< 5000 M(-1)), low dose (< 100 mg), and low CD:drug ratio (< 2:1). These general guidelines, however, did not apply to all studies. Quantitative guidelines useful to a formulation scientist considering the use of cyclodextrins were difficult to develop due to missing information and the complicated manner in which drug and cyclodextrin properties interact to influence key drug delivery processes (e.g., dissolution, absorption). The mechanisms by which cyclodextrins influence these processes, again emphasizing solubilization capabilities, are discussed to provide further insight into why cyclodextrins will increase bioavailability in certain cases but not influence or possibly decrease bioavailability in others.

Cyclodextrins in drug delivery: an updated review

The purpose of this review is to discuss and summarize some of the interesting findings and applications of cyclodextrins (CDs) and their derivatives in different areas of drug delivery, particularly in protein and peptide drug delivery and gene delivery. The article highlights important CD applications in the design of various novel delivery systems like liposomes, microspheres, microcapsules, and nanoparticles. In addition to their well-known effects on drug solubility and dissolution, bioavailability, safety, and stability, their use as excipients in drug formulation are also discussed in this article. The article also focuses on various factors influencing inclusion complex formation because an understanding of the same is necessary for proper handling of these versatile materials. Some important considerations in selecting CDs in drug formulation such as their commercial availability, regulatory status, and patent status are also summarized. CDs, because of their continuing ability to find several novel applications in drug delivery, are expected to solve many problems associated with the delivery of different novel drugs through different delivery routes.

In vitro controlled release of vinpocetine-cyclodextrin-tartaric acid multicomponent complexes from HPMC swellable tablets

The objective of this study was to investigate the effect of multicomponent complexation (MCC) of vinpocetine (VP), a poorly soluble base-type drug, with beta-cyclodextrin (betaCD), sulfobutylether beta-cyclodextrin (SBEbetaCD), tartaric acid (TA), polyvinylpyrrolidone (PVP) and hydroxypropylmethylcellulose (HPMC), on the design of controlled release hydrophilic HPMC tablets and to evaluate their in vitro release profiles by a pH gradient method. Multicomponent complexation led to enhanced dissolution properties of VP both in simulated gastric and intestinal fluids, and became possible the development of HPMC tablet formulations with more independent pH dissolution profiles. Drug release process was investigated experimentally using USP apparatus 3 and by means of model-independent parameters. Responses studied included similarity of dissolution profiles, time for 60% of the drug to dissolve (T(60%)), percent of VP released after 7 h (PD(7 h)) and the dissolution efficiency parameter at 12 h (DE(12 h)). Influence of multicomponent complexation was proved to increase the release of VP from HPMC tablets and superior PD(7 h) and DE(12 h) values were obtained in formulations containing VP-CD-TA complexes. Results supported the use of HPMC matrices to provide a useful tool in retarding the release of VP and that dissolution characteristics of the drug may be modulated by multicomponent complexation in these delivery systems, suggesting an improvement on VP bioavailability.

Preparation and characterization of starch/cyclodextrin bioadhesive microspheres as platform for nasal administration of Gabexate Mesylate (Foy®) in allergic rhinitis treatment

Bioadhesive and biodegradable microspheres were obtained by chemical cross-linking with epichlorohydrin of an alkaline solution of a mixture of starch and alpha-, beta-, or gamma-cyclodextrin (CyD). Microspheres were characterized by scanning electron microscopy, swelling degree, and water retention. The percentage of the effective CyD in microspheres was estimated by measuring the amount of iodine and typical organic compounds (TOCs) retained in the hydrophobic cavity of CyD. Gabexate Mesylate (trade name Foy); GM), an antiallergic drug, was included in microspheres by soaking in an aqueous solution containing the drug, followed by solvent evaporation or lyophilization. UV, IR, and DSC data indicated that despite the fact that GM is a hydrophilic drug, its hydrophobic moiety close to the benzene ring is able to penetrate the CyD cavity and to form stable inclusion complexes. Values of the association equilibrium constant for GM binding to CyD, obtained by UV differential spectroscopy, indicated that the affinity of the drug for alpha- and gamma-CyD is higher than that for beta-CyD. In vitro, GM was gradually released during 1h. Even if the release rate of the drug is relatively fast, the microspheres might actually provide the best platform since the material adheres to the nasal mucosa which was proved by adhesion tests. The GM integrity was checked by comparing its anti-trypsin activity before and after release.