The Biological Characteristics and Pharmacodynamics of a Mycophenolate Mofetil Nanosuspension Ophthalmic Delivery System in Rabbits

Recent Advances in Nanotechnology for the Treatment of Dry Eye Disease

Dry eye disease (DED) incidence is continuously growing, positioning it to become an emergent health issue over the next few years. Several topical treatments are commonly used to treat DED; however, reports indicate that only a minor proportion of drug bioavailability is achieved by the majority of eye drops available on the market. In this context, enhancing drug ability to overcome ocular barriers and prolonging its residence time on the ocular surface represent a new challenge in the field of ocular carrier systems. Therefore, research has focused on the development of multi-functional nanosystems, such as nanoemulsions, liposomes, dendrimers, hydrogels, and other nanosized carriers. These systems are designed to improve topical drug bioavailability and efficacy and, at the same time, require fewer daily administrations, with potentially reduced side effects. This review summarizes the different nanotechnologies developed, their role in DED, and the nanotechnology-based eyedrops currently approved for DED treatment.

Nano-based eye drop: Topical and noninvasive therapy for ocular diseases

Eye drops are the most accessible therapy for ocular diseases, while inevitably suffering from their lower bioavailability which highly restricts the treatment efficacy. The introduction of nanotechnology has attracted considerable interest as it has advantages over conventional ones such as prolonged ocular surface retention time and enhanced ocular barrier penetrating properties, and achieving higher bioavailability and improved treatment efficacy. This review describes various ocular diseases treated with eye drops as well as the physiological and anatomical ocular barriers faced with through drug administration. It also summarizes the recent advances regarding the utilization of nanotechnology in developing eye drops, and how to optimize the nanocarrier-based ocular drug delivery systems. The prospective future research directions for nano-based eye drops are also discussed here.

Interpenetrating polymeric network (IPNs) in ophthalmic drug delivery: Breaking the barriers

To maintain the therapeutic drug concentration for a prolonged period of time in aqueous and vitreous humor is primary challenge for ophthalmic drug delivery. Majority of the locally administered drug into the eye is lost as to natural reflexes like blinking and lacrimation resulting in the short span of drug residence. Consequently, less than 5% of the applied drug penetrate through the cornea and reaches the intraocular tissues. The major targets for optimal ophthalmic drug delivery are increasing drug residence time in cul-de-sac of the eye, prolonging intraocular exposure, modulating drug release from the delivery system, and minimizing pre-corneal drug loss. Development of in situ gel, contact lens, intraocular lens, inserts, artificial cornea, scaffold, etc., for ophthalmic drug delivery are few approaches to achieve these major targeted objectives for delivering the drug optimally. Interpenetrating polymeric network (IPN) or smart hydrogels or stimuli sensitive hydrogels are the class of polymers that can help to achieve the targets in ophthalmic drug delivery due to their versatility, biocompatibility and biodegradability. These novel ''smart" materials can alter their molecular configuration and result in volume phase transition in response to environmental stimuli, such as temperature, pH, ionic strength, electric and magnetic field. Hydrogel and tissue interaction, mechanical/tensile properties, pore size and surface chemistry of IPNs can also be modulated for tuning the drug release kinetics. Stimuli sensitive IPNs has been widely exploited to prepare in situ gelling formulations for ophthalmic drug delivery. Low refractive index hydrogel biomaterials with high water content, soft tissue-like physical properties, wettability, oxygen, glucose permeability and desired biocompatibility makes IPNs versatile candidate for contact lenses and corneal implants. This review article focuses on the exploration of these smart polymeric networks/IPNs for therapeutically improved ophthalmic drug delivery that has unfastened novel arenas in ophthalmic drug delivery.

Colloidal nanosystems with mucoadhesive properties designed for ocular topical delivery

Over the last years, the scientific interest about topical ocular delivery targeting the posterior segment of the eye has been increasing. This is probably due to the fact that this is a non-invasive administration route, well tolerated by patients and with fewer local and systemic side effects. However, it is a challenging task due to the external ocular barriers, tear film clearance, blood flow in the conjunctiva and choriocapillaris and due to the blood-retinal barriers, amongst other features. An enhanced intraocular bioavailability of drugs can be achieved by either improving corneal permeability or by improving precorneal retention time. Regarding this last option, increasing residence time in the precorneal area can be achieved using mucoadhesive polymers such as xyloglucan, poly(acrylate), hyaluronic acid, chitosan, and carbomers. On the other hand, colloidal particles can interact with the ocular mucosa and enhance corneal and conjunctival permeability. These nanosystems are able to deliver a wide range of drugs, including macromolecules, providing stability and improving ocular bioavailability. New pharmaceutical approaches based on nanotechnology associated to bioadhesive compounds have emerged as strategies for a more efficient treatment of ocular diseases. Bearing this in mind, this review provides an overview of the current mucoadhesive colloidal nanosystems developed for ocular topical administration, focusing on their advantages and limitations.

Solid Lipid Nanoparticles of Mycophenolate Mofetil: An Attempt to Control the Release of an Immunosuppressant

Introduction

Organ transplantation is a critically important procedure, which requires immune modulation by using immunosuppressants. Development of nanoparticles is an emerging and beneficial engineering process to increase the dissolution rate of poorly soluble immunosuppressants as well as to provide controlled release for better therapeutic outcomes.

Method

Currently, the nanoprecipitation method was employed to fabricate β-cyclodextrin (βCD) facilitated mycophenolate mofetil (MMF)-loaded solid lipid nanoparticles (SLNPs). The prime objectives of the study included, improvement of the dissolution profile of poorly aqueous soluble drug and controlled release from the SLNs to provide steady state drug concentration. Drug release from the prepared SLNs was assessed in two different media, ie, acidic buffer at pH 1.2 and phosphate buffer at pH 7.2 using USP dissolution apparatus for 12 h, followed by the evaluation of drug release mechanism and pattern by applying kinetic models.

Results

Justifiably, in acidic medium, the release was found to be 12% more (68%) in comparison to that in basic medium (56%). However, in both dissolution media, drug release was independent of initial concentration (R²>0.95) with non-Fickian type of diffusion mechanism. The outcomes of the study have exhibited that prepared formulations were in nanosized range (80–170 nm) with a net charge of ±23 charge on their surface. They possessed fairly uniform surface with acceptable polydispersity index (0.23±0.09). Scanning electron microscopy (SEM) analysis illustrated that the nanoparticles had uniform particle size and shape.

Discussion

The findings show potential applications of the nanoparticles and the method for the development of SLNPs in controlled release of MMF for better therapeutic outcomes. Conclusively, the prepared SLNPs were well designed in nanosized ranges and justifying the once daily controlled release formulation dose of MMF to enhance patient compliance.

Nanocrystals: An Overview of Fabrication, Characterization and Therapeutic Applications in Drug Delivery

Approximately 40 % drugs in the market are having poor aqueous solubility related problems and 70 % molecules in discovery pipeline are being practically insoluble in water. Nanocrystals is a prominent tool to solve the issue related to poor aqueous solubility and helps in improving the bioavailability of many drugs as reported in the literature. Nanocrystals can be prepared by top down methods, bottom up methods and combination methods. Many patented products such as Nanocrystals®, DissoCubes®, NANOEDGE® and SmartCrystals ®, etc., are available, which are based on these three preparation methodologies. The particle size reduction resulted into unstable nanocrystalline system and the phenomenon of Ostawald ripening occurs. This instability issue could be resolved by using an appropriate stabilizers or combination of stabilizers. The nanosuspensions could be transformed to the solid state to prevent particle aggregation in liquid state by employing various unit operations such as lyophilisation, spray drying, granulation and pelletisation. These techniques are well known for their scalability and continuous nanocrystal formation advantages. Nanocrystals can be characterized by using scanning electron microscopy, transmission electron microscopy, atomic force microscopy, differential scanning calorimetry, fourier transform infrared spectroscopy, powdered x- ray diffraction and photon correlation spectroscopy. The downscaling of nanocrystals will enable rapid optimization of nanosuspension formulation in parallel screening design of preclinical developmental stage drug moieties. One of the most acceptable advantages of nanocrystals is their wide range of applicability such as oral delivery, ophthalmic delivery, pulmonary delivery, transdermal delivery, intravenous delivery and targeting (brain and tumor targeting). The enhancement in market value of nanocrystals as well as the amount of nanocrystal products in the market is gaining attention to be used as an approach in order to get commercial benefits.

Engineered nanocrystal technology: in-vivo fate, targeting and applications in drug delivery

Formulation of nanocrystals is a robust approach which can improve delivery of poorly water soluble drugs, a challenge pharmaceutical industry has been facing since long. Large scale production of nanocrystals is done by techniques like precipitation, media milling and, high pressure homogenization. Application of appropriate stabilizers along with drying accords long term stability and commercial viability to nanocrystals. These can be administered through oral, parenteral, pulmonary, dermal and ocular routes showing their high therapeutic applicability. They serve to target drug molecules in specific regions through size manipulation and surface modification. This review dwells upon the in-vivo fate and varying applications in addition to the facets of drug nanocrystals stated above.

Development of PIK-75 nanosuspension formulation with enhanced delivery efficiency and cytotoxicity for targeted anti-cancer therapy

PIK-75 is a phosphatidylinositol 3-kinase (PI3K) inhibitor that shows selectivity toward p110-α over the other PI3K class Ia isoforms p110-β and p110-δ, but it lacks solubility, stability and other kinase selectivity. The purpose of this study was to develop folate-targeted PIK-75 nanosuspension for tumor targeted delivery and to improve therapeutic efficacy in human ovarian cancer model. High pressure homogenization was used to prepare the non-targeted and targeted PIK-75 nanosuspensions which were characterized for size, zeta potential, entrapment efficiency, morphology, saturation solubility and dissolution velocity. In vitro analysis of drug uptake, cell viability and cell survival was conducted in SKOV-3 cells. Drug pharmacokinetics and pAkt expression were determined in SKOV-3 tumor bearing mice. PIK-75 nanosuspensions showed an improvement in dissolution velocity and an 11-fold increase in saturation solubility over pre-milled PIK-75. In vitro studies in SKOV-3 cells indicated a 2-fold improvement in drug uptake and 0.4-fold decrease in IC50 value of PIK-75 following treatment with targeted nanosuspension compared to non-targeted nanosuspension. The improvement in cytotoxicity was attributed to an increase in caspase 3/7 and hROS activity. In vivo studies indicated a 5-10-fold increased PIK-75 accumulation in the tumor with both the nanosuspension formulations compared to PIK-75 suspension. The targeted nanosuspension showed an enhanced downregulation of pAkt compared to non-targeted formulation system. These results illustrate the opportunity to formulate PIK-75 as a targeted nanosuspension to enhance uptake and cytotoxicity of the drug in tumor.