Amal K. Hussein

Conjunctival and corneal tolerability assessment of ocular naltrexone niosomes and their ingredients on the hen's egg chorioallantoic membrane and excised bovine cornea models.

This study aimed at combining the hens egg test-chorioallantoic membrane (HET-CAM), bovine corneal opacity and permeability (BCOP) test and histological examination of excised corneas to evaluate the conjunctival and corneal toxicity of niosomes and their ingredients. Various surfactant/lipid combinations and concentrations (1-10%, w/v) were investigated for the ocular delivery of an ambitious drug (naltrexone hydrochloride) for treatment of diabetic keratopathy. Four niosomal formulations were investigated and found to be non irritant to the 10 days old HET-CAMs (an acceptable conjunctival model). Only one of the tested ingredients (sodium cholate - CH) showed moderate irritation, however such an effect was diminished when incorporated into niosomes. Corneal opacity and fluorescein permeability scores for the test substances correlated well with the HET-CAM test results. Corneal erosion and stromal thickness were found to be in agreement with the HET-CAM and BCOP results, which discriminated well between moderately and mildly irritant test substances. Corneal histological examination revealed toxicity signs included epithelial erosion, stromal condensation and stromal vacuolisation, which allowed better discrimination between strong and moderate irritants. It is concluded that the prepared niosomes possess good ocular tolerability and minimal ocular tissue irritation. They can be further investigated as ocular delivery systems using appropriate animal models.

Formulation and corneal permeation of ketorolac tromethamine-loaded chitosan nanoparticles

Abstract The aim of this work was to formulate chitosan (CS)-based nanoparticles (NPs) loaded with ketorolac tromethamine (KT) intended for topical ocular delivery. NPs were prepared using ionic gelation method incorporating tri-polyphosphate (TPP) as cross-linker. Following the preparation, the composition of the system was optimized in terms of their particle size, zeta potential, entrapment efficiency (EE) and morphology, as well as performing structural characterization studies using Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). The data suggested that the size of the NPs was affected by CS/TPP ratio where the diameter of the NPs ranged from 108.0 ± 2.4 nm to 257.2 ± 18.6 nm. A correlation between drug EE and the corresponding drug concentration added to the formulation was observed, where the EE of the NPs increased with increasing drug concentration, for up to 10 mg/mL. FT-IR and DSC revealed that KT was dispersed within the NPs where the phosphate groups of TPP were associated with the ammonium groups of CS. The in vitro release profile of KT from CS NPs showed significant differences (p < 0.05) compared to KT solution. Furthermore, mucoadhesion studies revealed adhesive properties of the formulated NPs. The KT-loaded NPs were found to be stable when stored at different storage conditions for a period of 3 months. The ex vivo corneal permeation studies performed on excised porcine eye balls confirmed the ability of NPs in retaining the drug on the eye surface for a relatively longer time. These results demonstrate the potential of CS-based NPs for the ocular delivery of KT.

Poloxamer-based thermoresponsive ketorolac tromethamine in situ gel preparations: Design, characterisation, toxicity and transcorneal permeation studies

&NA; This study was aimed at preparing, characterising and evaluating in situ gel formulations based on a blend of two hydrophilic polymers i.e. poloxamer 407 (P407) and poloxamer 188 (P188) for a sustained ocular delivery of ketorolac tromethamine (KT). Drug‐polymer interaction studies were performed using DSC and FT‐IR. The gelation temperature (Tsol‐gel), gelation time, rheological behaviour, mucoadhesive characteristics of these gels, transcorneal permeation and ocular irritation as well as toxicity was investigated. DSC and FT‐IR studies revealed that there may be electrostatic interactions between the drug and the polymers used. P188 modified the Tsol/gel of P407 bringing it close to eye temperature (35 °C) compared with the formulation containing P407 alone. Moreover, gels that comprised P407 and P188 exhibited a pseudoplastic behaviour at different concentrations. Furthermore, mucoadhesion study using mucin discs showed that in situ gel formulations have good mucoadhesive characteristics upon increasing the concentration of P407. When comparing formulations PP11 and PP12, the work of adhesion decreased significantly (P < 0.001) from 377.9 ± 7.79 mN mm to 272.3 ± 6.11 mN mm. In vitro release and ex vivo permeation experiments indicated that the in situ gels were able to prolong and control KT release as only 48% of the KT released within 12 h. In addition, the HET‐CAM and BCOP tests confirmed the non‐irritancy of KT loaded in situ gels, and HET‐CAM test demonstrated the ability of ocular protection against strongly irritant substances. MTT assay on primary corneal epithelial cells revealed that in situ gel formulations loaded with KT showed reasonable and acceptable percent cell viability compared with control samples. Graphical abstract In this study, the thermoresponsive behaviour of poloxamers was employed as a trigger for the formation of in situ gel systems incorporating ketorolac tromethamine (KT) (A). The protective effect of KT loaded in situ gel preparation on 10 day old chorioallantoic membrane (CAM) has been investigated after treating the CAM with a strong irritant, NaOH (B). The BCOP test revealed the corneal opacity and permeability of the prepared in situ gel system (C). The MTT cytotoxicity assay demonstrated that the cell viability when treated with the selected in situ gel preparations was at an acceptable level compared to the control samples (D). Figure. No caption available.

Preparation and evaluation of polyamidoamine dendrimer conjugate with glucuronylglucosyl-β-cyclodextrin (G3) as a novel carrier for siRNA.

Abstract In this study, we newly synthesized the polyamidoamine STARBURST dendrimer (dendrimer, generation 3: G3) conjugates with 6-O-α-(4-O-α-d-glucuronyl)-d-glucosyl-β-cyclodextrin [GUG-β-CDE (G3)] having the various degrees of substitution (DS) of GUG-β-cyclodextrin of 1.6, 3.0, 3.7, 5.0 and 8.6, and evaluated them as a siRNA transfer carrier. GUG-β-CDEs (G3) formed the positively charged and nano-order complexes with siRNA. Of the siRNA complexes with five GUG-β-CDEs (G3), the complex with GUG-β-CDE (G3, DS 3.7) showed the highest RNAi effect and cellular uptake with negligible cytotoxicity in KB cells at a charge ratio of 20. In addition, the RNAi effect and cellular uptake of the complex with GUG-β-CDE (G3, DS 3.7) were higher than those of α-CDE (G3, DS 2.4) and comparable to those of Lipofectamine™ 2000. Furthermore, the complex with GUG-β-CDE (G3, DS 3.7) possessed the endosomal escaping ability, the releasing property of siRNA in the cytoplasm and serum resistance. These results suggest that GUG-β-CDE (G3, DS 3.7) has the potential as a novel siRNA carrier.

Formulation and clinical evaluation of silymarin pluronic-lecithin organogels for treatment of atopic dermatitis

Silymarin is a naturally occurring flavonoid drug; evidence from recent research has highlighted its use as a potential treatment for atopic dermatitis (AD). Both poor water solubility and drug permeability have hindered the percutaneous absorption of silymarin. Formulation of silymarin into pluronic-lecithin organogel (PLO) basis for topical skin delivery is the main aim of this work. Six different PLO formulations were prepared containing various pluronic to lecithin ratios using two cosolvent systems of ethyl alcohol and dimethyl sulfoxide. Formulation 2 (20% pluronic and 3% lecithin) was found to be the optimal base for topical delivery of silymarin as it showed optimum pH, viscosity, drug content, and satisfactory in vitro silymarin permeation. The silymarin PLO formulation significantly relieved inflammatory symptoms of AD such as redness, swelling, and inflammation. These findings warrant the ability for application of these novel silymarin PLO formulations as a novel treatment for AD.

Improved corneal bioavailability of ofloxacin: biodegradable microsphere-loaded ion-activated in situ gel delivery system

The aim of the study was to improve corneal penetration and bioavailability of ofloxacin (OFX) eye preparations. OFX was incorporated in poly (lactide-co-glycolide) as biodegradable microspheres using oil in oil emulsion solvent evaporation technique. The prepared OFX microspheres were then incorporated in Gelrite® in situ gel preparation. In addition, OFX Gelrite-based in situ gel formulations were prepared. OFX formulations were characterized for gelling capacity, viscosity, and rheological properties. Release studies for OFX microspheres, OFX in situ gel, and OFX-loaded microspheres in situ gel formulations were carried out to investigate release characteristics of the drug. The prepared OFX formulations were then investigated in vivo compared with commercially available OFX eyedrops. Results showed that the optimum Gelrite concentration was at 0.4%–0.7% w/v; the prepared formulations were viscous liquid transformed into a pourable gel immediately after the addition of simulated tear fluid with a gelling factor of 27–35. Incorporation of OFX-loaded microspheres in Gelrite solution (0.4% w/v) significantly altered the release profiles of OFX-loaded microspheres in situ gel formula compared with the corresponding OFX gels and OFX microspheres. In vivo results in rabbits showed that OFX-loaded microspheres in situ gel formula improved the relative bioavailability by 11.7-fold compared with the commercially available OFX eyedrops. In addition, the longer duration of action of OFX-loaded microspheres in situ gel formula preparations is thought to avoid frequent instillations, which improves patient tolerability and compliance.

Improved in vitro dissolution parameters and in vivo hypolipidemic efficiency of atorvastatin calcium through the formation of hydrophilic inclusion complex with cyclodextrins

An aim of the present study was to improve the dissolution of the inherently low water solubility hypolipidemic agent, Atorvastatin calcium (ATC), through the preparation and characterization of ATC with cyclodextrins (CDs) inclusion complexes employing different techniques. A second goal was to study the in vivo hypolipidemic efficacy of ATC‐complexes with enhanced dissolution characteristics. Inclusion complexation of ATC with β‐cyclodextrin (β‐CD) and hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) was evaluated in aqueous and solid states. ATC formed inclusion complexes with β‐CD and HP‐β‐CD depending to a great extent upon ATC ionization state. Evaporation and freeze‐drying were the most efficient techniques to achieve complexation. In contrast, kneading was an inefficient tool to create true inclusion complexes, which could reflect the hindrance of drug–CDs interactions in the semisolid medium. The ATC:CD ratio of 1:2 showed better dissolution characteristics compared to a 1:1 ratio. Moreover, the in vivo hypolipidemic activities of ATC‐CDs (β‐CD and HP‐β‐CD) complexes were greater (P<0.05) than the other investigated formulations. Thus the nature of the carrier did not play a critical role in the dissolution characteristics of the inclusion system. In contrast, the carrier molar ratio, and the employed complexation technique were found to be key factors in enhancing the ATC dissolution rate, yielding performances as well as the in vivo hypolipidemic efficacies. Drug Dev Res 72: 379–390, 2011.

Flurbiprofen-loaded niosomes-in-gel system improves the ocular bioavailability of flurbiprofen in the aqueous humor

Abstract The present work aimed to prolong the contact time of flurbiprofen (FBP) in the ocular tissue to improve the drug anti-inflammatory activity. Different niosome systems were fabricated adopting thin-film hydration technique and using the nonionic surfactant Span 60. The morphology of the prepared niosomes was characterized by scanning electron microscopy (SEM). Physical characterization by differential scanning calorimetry, X-ray powder diffraction and Fourier transform infrared spectroscopy were conducted for the optimized formula (F5) that was selected on the basis of percent entrapment efficiency, vesicular size and total lipid content. F5 was formulated as 1% w/w Carpobol 934 gel. Pharmacokinetic parameters of FBP were investigated following ocular administration of F5-loaded gel system, F5 niosome dispersion or the corresponding FBP ocular drops to albino rabbits dispersion. Anti-inflamatory effect of F5-loaded carbopol gel was investigated by histopathological examination of the corneal tissue before and after the treatment of inflamed rabbit eye with the system. Results showed that cholesterol content, surfactant type. and total lipid contents had an apparent impact on the vesicle size of the formulated niosomes. Physical characterization revealed reduced drug crystallinity and incidence of interaction with other niosome contents. F5-loaded gel showed higher Cmax, area under the curve (AUC0–12), and thus higher ocular bioavailability than those of the corresponding FBP ocular solution. F5-loaded gel showed a promising rapid anti-inflammatory effect in the inflamed rabbit eye. These findings will eradicate the necessity for frequent ocular drug instillation and thus, improve patient compliance.

Optimisation of microstructured biodegradable finasteride formulation for depot parenteral application.

Abstract This study aimed to use the biocompatibility features of the biodegradable polymers to prepare depot injectable finasteride (FIN) microspheres for the treatment of benign prostatic hyperplasia. FIN microspheres were prepared utilising an emulsion–solvent evaporation/extraction technique. The Box–Behnken experimental design was adopted to optimise the preparation process. FIN plasma levels in albino rabbits were determined after injection with optimised FIN microspheres formula and compared with oral FIN suspension. Results revealed that the optimum microspheres displayed an amended sustained release pattern with lower initial burst. The cumulative FIN % released after 25 days was in the range 27.83–73.18% for F4 and F1, respectively. The optimised formula, with 50.0% (X1), and 22.316% (X2) and 1.38% (X3) showed 6.503 μm, 93.213%, 14.574%, and 64.838% for Y1, Y2, Y3, and Y4, respectively. In vivo studies displayed a sustained release pattern with minimal initial burst release when injected into rabbits.

Targeted siRNA delivery to tumor cells by folate-PEG-appended dendrimer/glucuronylglucosyl-β-cyclodextrin conjugate

We previously reported the utility of 6-O-α-(4-O-α-d-glucuronyl)-d-glucosyl-β-cyclodextrin (GUG-β-CyD) conjugates with polyamidoamine dendrimer [GUG-β-CDE (generation 3; G3)] as siRNA carriers. In this study, to prepare GUG-β-CDE (G3) possessing a targeting ability to tumor cells overexpressing folate receptor-α (FR-α), we newly synthesized folate-polyethylene glycol (PEG)-appended GUG-β-CDEs (G3) [Fol-PEG-GUG-β-CDEs (G3)] having degrees of substitution of folate (DSF) of 3.9, 6.7 and 7.3, and evaluated their utility as tumor-selective siRNA carriers. Of various Fol-PEG-GUG-β-CDEs (G3), Fol-PEG-GUG-β-CDE (G3, DSF6.7) showed the highest siRNA transfection activity at a charge ratio of 50 (carrier/siRNA) in both 786-0-luc cells [FR-α (+)] and KB cells [FR-α (+)]. In addition, the cellular uptake of the complex was significantly decreased by an addition of folic acid in a concentration-dependent manner, suggesting its FR-α-mediated endocytosis pathway. Moreover, Fol-PEG-GUG-β-CDE (G3, DSF6.7)/siRNA complex induced a potent RNAi effect, comparable to Lipofectamine™ 2000/siRNA complex. Furthermore, Fol-PEG-GUG-β-CDE (G3, DSF6.7) complex with siRNA against Polo-like kinase 1 (siPLK1) showed a significant cytotoxic activity in KB cells. Thus, Fol-PEG-GUG-β-CDE (G3, DSF6.7) has the potential as the targeted siRNA delivery carrier for FR-α-overexpressing tumor cells.