Fluconazole nanoparticles prepared by antisolvent precipitation technique: Physicochemical, in vitro, ex vivo and in vivo ocular evaluation

Development of antifungal fibrous ocular insert using freeze-drying technique

Candida species is one of the pathogenic fungi of the eye responsible for keratitis that frequently causes vision impairment and blindness. Effective treatment requires long-term use of antifungal drugs, which is opposed by the defensive mechanisms of the eye and inadequate corneal penetration. The objective of this study was to develop a carrier for prolonged ocular application of fluconazole (FLZ) to treat keratitis. FLZ was encapsulated into chitosan fibrous matrices (F1-F4) using different chitosan concentrations (0.02, 0.1, 0.5, and 1%w/v, respectively) by freeze-drying as a single-step technique. Studying the morphology and surface properties of the inserts revealed a porous matrix with fibrous features with a large surface area. Thermal stability and chemical compatibility were confirmed by DSC/TGA/DTA and FT-IR, respectively. Loading capacity (LC) and entrapment efficiency (EE) were determined. According to the in vitro release study, F4 (0.11 mg mg-1 LC and 87.53% EE) was selected as the optimum insert because it had the most sustained release, with 15.85% burst release followed by 75.62% release within 12 h. Ex vivo corneal permeation study revealed a 1.2-fold increase in FLZ permeation from F4 compared to FLZ aqueous solution. Also, in the in vivo pharmacokinetic study in rabbits, F4 increased the AUC0-8 of FLZ by 9.3-fold and its concentration in aqueous humor was maintained above the MIC through the experimentation time. Studies on cytotoxicity (MTT assay) provide evidence for the safety and biocompatibility of F4. Therefore, the freeze-dried FLZ-loaded chitosan fibrous insert could be a promising candidate for treating ocular keratitis.

Formulation and evaluation of Fluconazole Nanosuspensions: In vitro characterization and transcorneal permeability studies

The aim in this study was to develop and evaluate a nanofluconazole (FLZ) formulation with increased solubility and permeation rate using nanosuspensions. The FLZ nanosuspensions were stabilized using a variety of stabilizing agents and surfactants in various concentrations. The FLZ nanosuspension was characterized in vitro using particle size, zeta potential, X-ray powder diffraction (XRPD), and solubility. In addition, the ex vivo ocular permeation of FLZ through a goat cornea was analyzed. The results showed that the particle size of all nanosuspension formulations was in the nanometer range from 174.5 ± 1.9 to 720.2 ± 4.77 nm; that of the untreated drug was 18.34 μm. The zeta potential values were acceptable, which indicated suitable stability for formulations. The solubility of the nanosuspensions was up to 5.7-fold higher compared with that of the untreated drug. The results of the ex vivo ocular diffusion of the FLZ nanosuspensions showed the percentage of FLZ penetrating via the goat cornea increased after using Kollicoat to stabilize the nanosuspension formulation. Consequently, when using a nanosuspension formulation of Kollicoat, the antifungal activity of the drug strengthens.

Fostering the unleashing potential of nanocarriers-mediated delivery of ocular therapeutics

Ocular delivery is the most challenging aspect in the field of pharmaceutical research. The major hurdle for the controlled delivery of drugs to the eye includes the physiological static barriers such as the complex layers of the cornea, sclera and retina which restrict the drug from permeating into the anterior and posterior segments of the eye. Recent years have witnessed inventions in the field of conventional and nanocarrier drug delivery which have shown considerable enhancement in delivering small to large molecules across the eye. The dynamic challenges associated with conventional systems include limited drug contact time and inadequate ocular bioavailability resulting from solution drainage, tear turnover, and dilution or lacrimation. To this end, various bioactive-based nanosized carriers including liposomes, ethosomes, niosomes, dendrimer, nanogel, nanofibers, contact lenses, nanoprobes, selenium nanobells, nanosponge, polymeric micelles, silver nanoparticles, and gold nanoparticles among others have been developed to circumvent the limitations associated with the conventional dosage forms. These nanocarriers have been shown to achieve enhanced drug permeation or retention and prolong drug release in the ocular tissue due to their better tissue adherence. The surface charge and the size of nanocarriers (10-1000 nm) are the important key factors to overcome ocular barriers. Various nanocarriers have been shown to deliver active therapeutic molecules including timolol maleate, ampicillin, natamycin, voriconazole, cyclosporine A, dexamethasone, moxifloxacin, and fluconazole among others for the treatment of anterior and posterior eye diseases. Taken together, in a nutshell, this extensive review provides a comprehensive perspective on the numerous facets of ocular drug delivery with a special focus on bioactive nanocarrier-based approaches, including the difficulties and constraints involved in the fabrication of nanocarriers. This also provides the detailed invention, applications, biodistribution and safety-toxicity of nanocarriers-based therapeutcis for the ophthalmic delivery.

Nanocarriers significantly augment the absorption of ocular-delivered drugs: A comparative meta-analysis study

This study presents a meta-analysis that compiles information collected from several studies aiming to prove, by evidence, that nanocarriers out-perform conventional formulations in augmenting the bioavailability of ocular topically administered drugs. Data was further categorized into two subgroups; polymeric-based nanocarriers versus their lipid-based counterparts, as well as, naturally-driven carriers versus synthetically-fabricated ones. After normalization, the pharmacokinetic factor, area under the curve (AUC), was denoted as the "effect" in the conducted study, and the corresponding Forest plots were obtained. Our meta-analysis study confirmed the absorption enhancement effect of loading drugs into nanocarriers as compared to conventional topical ocular dosage forms. Interestingly, no significant differences were recorded between the polymeric and lipidic nanocarriers included in the study, while naturally-driven nanoplatforms were proven superior to the synthetic alternatives.

Liquid antisolvent crystallization of pharmaceutical compounds: current status and future perspectives

The present work reviews the liquid antisolvent crystallization (LASC) to prepare the nanoparticle of pharmaceutical compounds to enhance their solubility, dissolution rate, and bioavailability. The application of ultrasound and additives is discussed to prepare the particles with narrow size distribution. The use of ionic liquid as an alternative to conventional organic solvent is presented. Herbal compounds, also known for low aqueous solubility and limited clinical application, have been crystalized by LASC and discussed here. The particle characteristics such as particle size and particle size distribution are interpreted in terms of supersaturation, nucleation, and growth phenomena. To overcome the disadvantage of batch crystallization, the scientific literature on continuous flow reactors is also reviewed. LASC in a microfluidic device is emerging as a promising technique. The different design of the microfluidic device and their application in LASC are discussed. The combination of the LASC technique with traditional techniques such as high-pressure homogenization and spray drying is presented. A comparison of product characteristics prepared by LASC and the supercritical CO₂ antisolvent method is discussed to show that LASC is an attractive and inexpensive alternative for nanoparticle preparation. One of the major strengths of this paper is a discussion on less-explored applications of LASC in pharmaceutical research to attract the attention of future researchers.

Updates on applications of low-viscosity grade Hydroxypropyl methylcellulose in coprocessing for improvement of physical properties of pharmaceutical powders

Hydroxypropyl methylcellulose (HPMC) is an important polymeric excipient. Its versatility in terms of molecular weights and viscosity grades is the basis for its wide and successful application in the pharmaceutical industry. Low viscosity grades of HPMC (like E3 and E5) have been used as physical modifiers for pharmaceutical powders in recent years due to their unique physicochemical and biological properties (e.g., low surface tension, high T_g, strong hydrogen bonding ability, etc.). Such modification is the co-processing of HPMC with a drug/excipient to create composite particles (CPs) for the purpose of providing synergistic effects of functional improvement as well as of masking undesirable properties of the powder (e.g., flowability, compressibility, compactibility, solubility, stability, etc.). Therefore, given its irreplaceability and tremendous opportunities for future developments, this review summarized and updated studies on improving the functional properties of drugs and/or excipients by forming CPs with low-viscosity HPMC, analyzed and exploited the improvement mechanisms (e.g., improved surface properties, increased polarity, hydrogen bonding, etc.) for the further development of novel co-processed pharmaceutical powders containing HPMC. It also provides an outlook on the future applications of HPMC, aiming to provide a reference on the crucial role of HPMC in various areas for interested readers.

Optimization and Characterization of Low-Molecular-Weight Chitosan-Coated Baicalin mPEG-PLGA Nanoparticles for the Treatment of Cataract

The present study was to evaluate the potential effectiveness of low-molecular-weight chitosan-coated baicalin methoxy poly(ethylene glycol)-poly(d,l-lactic-co-glycolic acid) (mPEG-PLGA) nanoparticles (BA LCH NPs) for the treatment of cataract. mPEG-PLGA NPs were optimized by the Box-Behnken design and the central composite design based on the encapsulation efficiency and drug loading. Then, the BA LCH NPs were characterized based on morphology, particle size, and zeta potentials. The analytical data of differential scanning calorimetry, X-ray diffraction, and transmission electron microscopy depicted the drug excipient compatibility. In vitro, we evaluated cell viability, cellular uptake, potential ocular irritation, transcorneal permeability, and the precorneal retention of BA LCH NPs. In vivo, the chronic selenium cataract model was selected to assess the therapeutic effect of BA LCH NPs. The size of BA LCH NPs was within the range from 148 to 219 nm and the zeta potential was 19-25 mV. Cellular uptake results showed that the fluorescence intensity of the preparations in each group increased with time, and the fluorescence intensity of the LCH NP group was significantly higher than that of the solution group. The optimized BA LCH NPs improved precorneal residence time without causing eye irritation and also showed a sustained release of BA through the cornea for effective management of cataract. Also, fluorescence tracking on the rabbit cornea showed increased corneal retention of the LCH NPs. In addition, the results of therapeutic efficacy demonstrated that BA LCH NPs can significantly reduce the content of malondialdehyde and enhanced the activities of catalase, superoxide dismutase, and glutathione peroxidase, which was comparable to positive control and better than the BA solution group. Thus, it can be inferred that the BA LCH NPs are a promising drug delivery system for enhancing the ophthalmic administration of BA to the posterior segment of the eye and improving cataract symptoms.

Formulation and Evaluation of Transdermal Gel Containing Tacrolimus-Loaded Spanlastics: In Vitro, Ex Vivo and In Vivo Studies

Our goal was to prepare Span 60-based elastic nanovesicles (spanlastics (SPLs)) of tacrolimus (TCR) using the adapted ethanol injection method, characterize them, and evaluate their ability to improve the transdermal permeation of the active substance. The impact of two different concentrations of penetration enhancers, namely, propylene glycol and oleic acid, on the entrapment efficiency, vesicle size, and zeta potential was assessed. Moreover, in vitro release through a semipermeable membrane and ex vivo penetration through hairless rat skin were performed. Morphological examination and pharmacokinetics were performed for one selected formulation (F3OA1). TCR-loaded SPLs were effectively formulated with two different concentrations of permeation enhancers, and the effect of these enhancers on their physicochemical properties differed in accordance with the concentration and kind of enhancer used. The results of in vitro release displayed a considerable (p < 0.05) enhancement compared to the suspension of the pure drug, and there was a correlation between the in vitro and ex vivo results. The selected TCR-loaded nanovesicles incorporated into a gel base showed appreciable advantages over the oral drug suspension and the TCR-loaded gel. Additionally, the pharmacokinetic parameters were significantly (p < 0.05) improved based on our findings. Moreover, the AUC0−7 ng·h/mL form F3 OA1 was 3.36-fold higher than that after the administration of the TCR oral suspension.

Cellulosic Polymers for Enhancing Drug Bioavailability in Ocular Drug Delivery Systems

One of the major impediments to drug development is low aqueous solubility and thus poor bioavailability, which leads to insufficient clinical utility. Around 70–80% of drugs in the discovery pipeline are suffering from poor aqueous solubility and poor bioavailability, which is a major challenge when one has to develop an ocular drug delivery system. The outer lipid layer, pre-corneal, dynamic, and static ocular barriers limit drug availability to the targeted ocular tissues. Biopharmaceutical Classification System (BCS) class II drugs with adequate permeability and limited or no aqueous solubility have been extensively studied for various polymer-based solubility enhancement approaches. The hydrophilic nature of cellulosic polymers and their tunable properties make them the polymers of choice in various solubility-enhancement techniques. This review focuses on various cellulose derivatives, specifically, their role, current status and novel modified cellulosic polymers for enhancing the bioavailability of BCS class II drugs in ocular drug delivery systems.