Nanosponge-Mediated Drug Delivery Lowers Intraocular Pressure

From Eye Care to Hair Growth: Bimatoprost

BACKGROUND

Bimatoprost has emerged as a significant medication in the field of medicine over the past several decades, with diverse applications in ophthalmology, dermatology, and beyond. Originally developed as an ocular hypotensive agent, it has proven highly effective in treating glaucoma and ocular hypertension. Its ability to reduce intraocular pressure has established it as a first-line treatment option, improving management and preventing vision loss. In dermatology, bimatoprost has shown promising results in the promotion of hair growth, particularly in the treatment of alopecia and hypotrichosis. Its mechanism of action, stimulating the hair cycle and prolonging the growth phase, has led to the development of bimatoprost-containing solutions for enhancing eyelash growth.

AIM

The aim of our review is to provide a brief description, overview, and studies in the current literature regarding the versatile clinical use of bimatoprost in recent years. This can help clinicians determine the most suitable individualized therapy to meet the needs of each patient.

METHODS

Our methods involve a comprehensive review of the latest advancements reported in the literature in bimatoprost formulations, which range from traditional eye drops to sustained-release implants. These innovations offer extended drug delivery, enhance patient compliance, and minimize side effects.

RESULTS

The vast literature published on PubMed has confirmed the clinical usefulness of bimatoprost in lowering intraocular pressure and in managing patients with glaucoma. Numerous studies have shown promising results in dermatology and esthetics in promoting hair growth, particularly in treating alopecia and hypotrichosis. Its mechanism of action involves stimulating the hair cycle and prolonging the growth phase, leading to the development of solutions that enhance eyelash growth. The global use of bimatoprost has expanded significantly, with applications growing beyond its initial indications. Ongoing research is exploring its potential in glaucoma surgery, neuroprotection, and cosmetic procedures.

CONCLUSIONS

Bimatoprost has shown immense potential for addressing a wide range of therapeutic needs through various formulations and advancements. Promising future perspectives include the exploration of novel delivery systems such as contact lenses and microneedles to further enhance drug efficacy and patient comfort. Ongoing research and future perspectives continue to shape its role in medicine, promising further advancements and improved patient outcomes.

Ocular Delivery of Bimatoprost-Loaded Solid Lipid Nanoparticles for Effective Management of Glaucoma

Glaucoma is a progressive optic neuropathy characterized by a rise in the intraocular pressure (IOP) leading to optic nerve damage. Bimatoprost is a prostaglandin analogue used to reduce the elevated IOP in patients with glaucoma. The currently available dosage forms for Bimatoprost suffer from relatively low ocular bioavailability. The objective of this study was to fabricate and optimize solid lipid nanoparticles (SLNs) containing Bimatoprost for ocular administration for the management of glaucoma. Bimatoprost-loaded SLNs were fabricated by solvent evaporation/ultrasonication technique. Glyceryl Monostearate (GMS) was adopted as solid lipid and poloxamer 407 as surfactant. Optimization of SLNs was conducted by central composite design. The optimized formulation was assessed for average particle size, entrapment efficiency (%), zeta potential, surface morphology, drug release study, sterility test, isotonicity test, Hen's egg test-chorioallantoic membrane (HET-CAM) test and histopathology studies. The optimized Bimatoprost-loaded SLNs formulation had an average size of 183.3 ± 13.3 nm, zeta potential of -9.96 ± 1.2 mV, and encapsulation efficiency percentage of 71.8 ± 1.1%. Transmission electron microscopy (TEM) study revealed the nearly smooth surface of formulated particles with a nano-scale size range. In addition, SLNs significantly sustained Bimatoprost release for up to 12 h, compared to free drug (p < 005). Most importantly, HET-CAM test nullified the irritancy of the formulation was verified its tolerability upon ocular use, as manifested by a significant reduction in mean irritation score, compared to positive control (1% sodium dodecyl sulfate; p < 0.001). Histopathology study inferred the absence of any signs of cornea tissue damage upon treatment with Bimatoprost optimized formulation. Collectively, it was concluded that SLNs might represent a viable vehicle for enhancing the corneal permeation and ocular bioavailability of Bimatoprost for the management of glaucoma.

Travoprost Liquid Nanocrystals: An Innovative Armamentarium for Effective Glaucoma Therapy

To date, the ophthalmic application of liquid crystalline nanostructures (LCNs) has not been thoroughly reconnoitered, yet they have been extensively used. LCNs are primarily made up of glyceryl monooleate (GMO) or phytantriol as a lipid, a stabilizing agent, and a penetration enhancer (PE). For optimization, the D-optimal design was exploited. A characterization using TEM and XRPD was conducted. Optimized LCNs were loaded with the anti-glaucoma drug Travoprost (TRAVO). Ex vivo permeation across the cornea, in vivo pharmacokinetics, and pharmacodynamic studies were performed along with ocular tolerability examinations. Optimized LCNs are constituted of GMO, Tween® 80 as a stabilizer, and either oleic acid or Captex® 8000 as PE at 25 mg each. TRAVO-LNCs, F-1-L and F-3-L, showed particle sizes of 216.20 ± 6.12 and 129.40 ± 11.73 nm, with EE% of 85.30 ± 4.29 and 82.54 ± 7.65%, respectively, revealing the highest drug permeation parameters. The bioavailability of both attained 106.1% and 322.82%, respectively, relative to the market product TRAVATAN®. They exhibited respective intraocular pressure reductions lasting for 48 and 72 h, compared to 36 h for TRAVATAN®. All LCNs exhibited no evidence of ocular injury in comparison to the control eye. The findings revealed the competence of TRAVO-tailored LCNs in glaucoma treatment and suggested the potential application of a novel platform in ocular delivery.

Intraocular nano-microscale drug delivery systems for glaucoma treatment: design strategies and recent progress

Glaucoma is a leading cause of irreversible visual impairment and blindness, affecting over 76.0 million people worldwide in 2020, with a predicted increase to 111.8 million by 2040. Hypotensive eye drops remain the gold standard for glaucoma treatment, while inadequate patient adherence to medication regimens and poor bioavailability of drugs to target tissues are major obstacles to effective treatment outcomes. Nano/micro-pharmaceuticals, with diverse spectra and abilities, may represent a hope of removing these obstacles. This review describes a set of intraocular nano/micro drug delivery systems involved in glaucoma treatment. Particularly, it investigates the structures, properties, and preclinical evidence supporting the use of these systems in glaucoma, followed by discussing the route of administration, the design of systems, and factors affecting in vivo performance. Finally, it concludes by highlighting the emerging notion as an attractive approach to address the unmet needs for managing glaucoma.

Nanosponges- Versatile Platform as Drug Carrier

BACKGROUND

Recently, nano-drug delivery systems have become an integral part of the most novel drug delivery systems and have gained considerable importance owing to various advantages such as carriers for poorly soluble drugs, targeting molecules at the desired site, protection from degradation etc. Objective: One of the most studied areas of nanotechnology is nanosponges. The objective of this review was to extensively summarize the various strategies for the preparation, characterization and applications of nanosponges.

METHODS

In the current mini-review, we conducted a systemic search of the literature and patent inventions focusing on nanosponges. The summary of the search was inclusive of various aspects of nanosponges, such as drug characteristics to be considered while incorporating in nanosponges, other crucial additives during formulation of nanosponges, methods of preparation, characterization and applications of nanosponges in pharmaceuticals.

RESULTS

Nanosponges are nanocarriers for both lipophilic and hydrophilic drugs. These are prepared by different methods such as emulsion-solvent evaporation, solvent method, melting method, ultrasound assisted method etc., and all these methods were less time consuming, more economical and evaluated by sophisticated techniques available for routine analysis. These are among the most feasible alternative to address several formulation difficulties associated with the physicochemical properties of the drug. The porous nature and small particle size are vital properties of the nanosponges that contribute crucially to correcting the drawbacks of the drug. The properties of the nanosponges can be enhanced when combined with cyclodextrins. Extensive research work has been carried out in past to explore cyclodextrin based nanosponges. Besides, it is also used for smart targeting of tumors and for drug release in a sustainable pattern. Nanosponges can be prepared by simple methods. These can be tuned to release the drug by different routes so as to achieve the maximum benefits of the drug.

CONCLUSION

Huge amount of research has been carried out on nanosponges as drug carrier. The method of preparation and characterization of nanosponges are quite economical and routinely available. Owing to potential benefits and probable applications, these can be used as efficient carriers for certain drugs. The authors expect that the current review will guide the investigation of the nanosponges as nanodrug delivery systems.

Extraocular, periocular, and intraocular routes for sustained drug delivery for glaucoma

Although once daily anti-glaucoma drug therapy is a current clinical reality, most therapies require multiple dosing and there is an unmet need to develop convenient, safe, and effective sustained release drug delivery systems for long-term treatment to improve patient adherence and outcomes. One of the first sustained release drug delivery systems was approved for the reduction of intraocular pressure in glaucoma patients. It is a polymeric reservoir-type insert delivery system, Ocusert™, placed under the eyelid and on the ocular surface for zero-order drug release over one week. The insert, marketed in two strengths, released pilocarpine on the eye surface. While many clinicians appreciated this drug product, it was eventually discontinued. No similar sustained release non-invasive drug delivery system has made it to the market to date for treating glaucoma. Drug delivery systems under development include punctal plugs, ring-type systems, contact lenses, implants, microspheres, nanospheres, gels, and other depot systems placed in the extraocular, periocular, or intraocular regions including intracameral, supraciliary, and intravitreal spaces. This article discusses the advantages and disadvantages of the various routes of administration and delivery systems for sustained glaucoma therapy. It also provides the reader with some examples and discussion of drug delivery systems that could potentially be applied for glaucoma treatment. Interestingly, one intracamerally injected implant, Durysta™, was approved recently for sustained intraocular pressure reduction. However, long-term acceptance of such devices has yet to be established. The ultimate success of the delivery system will depend on efficacy relative to eye drop dosing, safety, reimbursement options, and patient acceptance. Cautious development efforts are warranted considering prior failed approaches for sustained glaucoma drug delivery. Neuroprotective approaches for glaucoma therapy including cell, gene, protein, and drug-combination therapies, mostly administered intravitreally, are also rapidly progressing towards assessment in humans.

Monitoring New Long-Lasting Intravitreal Formulation for Glaucoma with Vitreous Images Using Optical Coherence Tomography

Intravitreal injection is the gold standard therapeutic option for posterior segment pathologies, and long-lasting release is necessary to avoid reinjections. There is no effective intravitreal treatment for glaucoma or other optic neuropathies in daily practice, nor is there a non-invasive method to monitor drug levels in the vitreous. Here we show that a glaucoma treatment combining a hypotensive and neuroprotective intravitreal formulation (IF) of brimonidine–Laponite (BRI/LAP) can be monitored non-invasively using vitreoretinal interface imaging captured with optical coherence tomography (OCT) over 24 weeks of follow-up. Qualitative and quantitative characterisation was achieved by analysing the changes in vitreous (VIT) signal intensity, expressed as a ratio of retinal pigment epithelium (RPE) intensity. Vitreous hyperreflective aggregates mixed in the vitreous and tended to settle on the retinal surface. Relative intensity and aggregate size progressively decreased over 24 weeks in treated rat eyes as the BRI/LAP IF degraded. VIT/RPE relative intensity and total aggregate area correlated with brimonidine levels measured in the eye. The OCT-derived VIT/RPE relative intensity may be a useful and objective marker for non-invasive monitoring of BRI/LAP IF.

Brimonidine-LAPONITE® intravitreal formulation has an ocular hypotensive and neuroprotective effect throughout 6 months of follow-up in a glaucoma animal model

Intravitreal administration is widely used in ophthalmological practice to maintain therapeutic drug levels near the neuroretina and because drug delivery systems are necessary to avoid reinjections and sight-threatening side effects. However, currently there is no intravitreal treatment for glaucoma. The brimonidine-LAPONITE® formulation was created with the aim of treating glaucoma for extended periods with a single intravitreal injection. Glaucoma was induced by producing ocular hypertension in two rat cohorts: [BRI-LAP] and [non-bri], with and without treatment, respectively. Eyes treated with brimonidine-LAPONITE® showed lower ocular pressure levels up to week 8 (p < 0.001), functional neuroprotection explored by scotopic and photopic negative response electroretinography (p = 0.042), and structural protection of the retina, retinal nerve fibre layer and ganglion cell layer (p = 0.038), especially on the superior-inferior axis explored by optical coherence tomography, which was corroborated by a higher retinal ganglion cell count (p = 0.040) using immunohistochemistry (Brn3a antibody) up to the end of the study (week 24). Furthermore, delayed neuroprotection was detected in the contralateral eye. Brimonidine was detected in treated rat eyes for up to 6 months. Brimonidine-LAPONITE® seems to be a potential sustained-delivery intravitreal drug for glaucoma treatment.

Effects of shell thickness of hollow poly(lactic acid) nanoparticles on sustained drug delivery for pharmacological treatment of glaucoma

Structural designing of carriers with extended drug release profiles is critically important for achieving long-acting drug delivery systems toward efficient managements of chronic diseases. Here, we present a strategy to exploit the effects of the shell thickness of hollow poly(lactic acid) nanoparticles (HPLA NPs) in sustained glaucoma therapy. Formulations based on pilocarpine-loaded HPLA NPs with tailorable shell thickness ranging from 10 to 100 nm were shown to be highly compatible with human lens epithelial cells in vitro and with rabbit eyes in vivo. Specifically, shell thickness regulated the release of pilocarpine, with thick shells (~70 to 100 nm) providing sustained drug release performance but limited drug-loading efficiency, whereas ultrathin shells (~10 nm) induced the opposite effects. Remarkably, moderately thick shells (~40 nm) showed the most effective release profile of pilocarpine (above the therapeutic levels of ~10 µg/mL for over 56 days). In a rabbit model of glaucoma, single intracameral administration of an HPLA NP-based formulation with shell thickness of ~40 nm sustainably alleviated ocular hypertension for over 56 days, consequently protecting the structural integrity of the corneal endothelium, preserving the electrophysiological functions of the retina, and attenuating retinal and optic nerve degeneration in progressively glaucomatous eyes. The findings therefore implied a promising use of shell thickness effects in the development of long-acting drug delivery systems for pharmacological treatment of chronic ocular diseases. STATEMENT OF SIGNIFICANCE: Owing to their large surface areas and modifiable structures, nanoparticles have been considered as a promising platform for drug delivery; however, achieving drug nanocarrier systems with reduced burst release and sustained therapeutic efficacy remains challenges. This work presents the first report on rational design of hollow poly(lactic acid) nanocarriers for tailoring the structure-property-function relationships toward effective treatment of glaucoma. The shell thickness of the hollow nanocarriers is demonstrated to have influential impacts on pilocarpine encapsulation efficiency and release profile, indicating that the most sustained delivery performance (maintaining the release of pilocarpine above therapeutic level over 56 days) can be obtained for the polymeric nanoparticles with moderate shell thickness of ~40 nm.

Nanoemulsion as a feasible and biocompatible carrier for ocular delivery of travoprost: Improved pharmacokinetic/pharmacodynamic properties

Travoprost is a synthetic prostaglandin F2α analogue used in treatment of glaucoma. Due to its water insolubility and oily nature, novel delivery systems need to be developed to enhance its bioavailability, and sustain its release. In the current work, travoprost nanoemulsion was explored as a novel carrier prepared using low energy technique. Results showed that travoprost nanoemulsions exhibited suitable nanodroplet size, zeta potential, pH, refractive index, controlled release, as well as sufficient stability under accelerated conditions. In vivo studies delineated the enhanced absorption of travoprost nanoemulsion compared to the marketed eye drops Travatan®, as proven by the higher C_max and AUC of the former, and its prolonged intraocular pressure reduction time. Moreover, the nanoemulsion formulation was proven safe and non-irritant to ocular surfaces. Therefore, it can be suggested that travoprost nanoemulsion is a promising ocular delivery system for glaucoma treatment.

Advancing the stimuli response of polymer-based drug delivery systems for ocular disease treatment

Recent exploitations of stimuli-responsive polymers as ophthalmic drug delivery systems for the treatment of eye diseases are summarized and discussed.

Nanotechnology for Medical and Surgical Glaucoma Therapy-A Review

Glaucoma is the second leading cause of blindness worldwide. Even though significant advances have been made in its management, currently available antiglaucoma therapies suffer from considerable drawbacks. Typically, the success and efficacy of glaucoma medications are undermined by their limited bioavailability to target tissues and the inadequate adherence demonstrated by patients with glaucoma. The latter is due to a gradual decrease in tolerability of lifelong topical therapies and the significant burden to patients of prescribed stepwise antiglaucoma regimens with frequent dosing which impact quality of life. On the other hand, glaucoma surgery is restricted by the inability of antifibrotic agents to efficiently control the wound healing process without causing severe collateral damage and long-term complications. Evolution of the treatment paradigm for patients with glaucoma will ideally include prevention of retinal ganglion cell degeneration by the successful delivery of neurotrophic factors, anti-inflammatory drugs, and gene therapies. Nanotechnology-based treatments may surpass the limitations of currently available glaucoma therapies through optimized targeted drug delivery, increased bioavailability, and controlled release. This review addresses the recent advances in glaucoma treatment strategies employing nanotechnology, including medical and surgical management, neuroregeneration, and neuroprotection.

Towards A Microbead Occlusion Model of Glaucoma for a Non-Human Primate

Glaucoma is a group of optic neuropathies associated with aging and sensitivity to intraocular pressure (IOP). The disease causes vision loss through the degeneration of retinal ganglion cell neurons and their axons in the optic nerve. Using an inducible model of glaucoma, we elevated IOP in the squirrel monkey (Saimiri boliviensis) using intracameral injection of 35 μm polystyrene microbeads and measured common pathogenic outcomes in the optic projection. A 42% elevation in IOP over 28 weeks reduced anterograde transport of fluorescently-labeled cholera toxin beta from retina to the lateral geniculate nucleus (60% decrease), and to the superior colliculus (49% decrease). Pressure also reduced survival of ganglion cellaxons in the optic nerve by 22%. The same elevation caused upregulation of proteins associated with glaucomatous neurodegeneration in the retina and optic nerve, including complement 1q, interleukin 6, and brain-derived neurotrophic factor. That axon degeneration in the nerve lagged deficits in anterograde transport is consistent with progression in rodent models, while the observed protein changes also occur in tissue from human glaucoma patients. Thus, microbead occlusion in a non-human primate with a visual system similar to our own represents an attractive model to investigate neurodegenerative mechanisms and therapeutic interventions for glaucoma.

New pharmacotherapy for the treatment of glaucoma

INTRODUCTION

Glaucoma is the second leading cause of blindness in the world and current pharmacotherapies for glaucoma have remained relatively unchanged (with the exception of fixed combinations of previously available medications) since the mid-1990s with the development of prostaglandin analogues. Now, with both new formulations and new classes of medications with novel mechanisms of action, the medical therapy of glaucoma may be heralding a new dawn in medical management. Areas covered: This review outlines new topical therapies for intraocular pressure (IOP) lowering treatment, in addition to new formulations, preservative-free options, and advances in glaucoma medical therapy delivery. We performed a comprehensive search for published studies for glaucoma medical therapy using the electronic database PubMed. A manual search for each therapy or delivery system was also performed. Expert commentary: These advances in glaucoma therapy have the potential to overcome many barriers to glaucoma's medical care, particularly in terms of adherence. However, both time and research are needed to prove the relative efficacy and safety of these new pharmacotherapies and products, helping us decide their role in the treatment of elevated intraocular pressure. We are hopeful that these new developments in therapy may bring more options for glaucoma medical therapy.

Sustained drug delivery for glaucoma: current data and future trends

PURPOSE OF REVIEW

Sustained drug delivery has been recognized as a need for patients with ocular hypertension or glaucomatous optic neuropathy. Several sustained drug delivery systems and devices are currently on the horizon. This review aims to summarize initial results with these platforms, as reported in the literature, and also provide insight into their possible role in the glaucoma treatment paradigm.

RECENT FINDINGS

Sustained drug delivery systems currently on the horizon include the topical bimatoprost ocular insert, travoprost and latanoprost punctal plugs, latanoprost-eluting contact lenses, bimatoprost and travoprost intraocular implants, as well as several other therapies in earlier stages of development. Delivery strategies differ with respect to ocular site of implantation, ocular hypotensive agent, and duration of efficacy. Efficacy and safety outcomes with these devices are favorable thus far.

SUMMARY

The glaucoma treatment paradigm is currently in a state of flux as sustained drug delivery systems bring promise to individuals suffering from ocular hypertension or glaucoma. Several options will likely become available in the near future to ease the burden of daily administration of chronic therapy with intraocular pressure-lowering agents.

Eccentric position of the germinal vesicle and cortical flow during oocyte maturation specify the animal-vegetal axis of ascidian embryos

The animal-vegetal (A-V) axis is already set in unfertilized eggs. It plays crucial roles to coordinate germ-layer formation. However, how the A-V axis is set has not been well studied. In ascidians, unfertilized eggs are already polarized along the axis in terms of cellular components. The polarization occurs during oocyte maturation. Oocytes within the gonad have the germinal vesicle (GV) close to the future animal pole. When the GVs of full-grown oocytes were experimentally translocated to the opposite pole by centrifugal force, every aspect that designates A-V polarity was reversed in the eggs and embryos. This was confirmed by examining the cortical allocation of the meiotic spindle, position of the polar body emission, polarized distribution of mitochondria and postplasmic/PEM mRNA, direction of the cortical flow during oocyte maturation, cleavage pattern, and germ-layer formation during embryogenesis. Therefore, the eccentric position of the GV triggers subsequent polarizing events and establishes the A-V axis in eggs and embryos. We emphasize important roles of the cortical flow. This is the first report in which the A-V axis was experimentally and completely reversed in animal oocytes before fertilization.

Neuroprotective therapies in glaucoma: I. Neurotrophic factor delivery

Glaucoma is a neurodegenerative eye disease that causes permanent blindness at the progressive stage and the number of people affected worldwide is expected to reach over 79 million by 2020. Currently, glaucoma management relies on pharmacological and invasive surgical treatments mainly by reducing the intraocular pressure (IOP), which is the most important risk factor for the progression of the visual field loss. Recent research suggests that neuroprotective or neuroregenerative approaches are necessary to prevent retinal ganglion cells (RGCs) loss and visual impairment over time. Neuroprotection is a new therapeutic strategy that attempts to keep RGCs alive and functional. New gene and cell therapeutics encoding neurotrophic factors (NTFs) are emerging for both neuroprotection and regenerative treatments for retinal diseases. This article briefly reviews the role of NTFs in glaucoma and the potential delivery systems.