Development and evaluation of doxycycline niosomal thermoresponsive in situ gel for ophthalmic delivery

In situ gelling systems for ocular drug delivery

In situ gelling systems represent a burgeoning paradigm in ocular drug administration, addressing intrinsic challenges posed by extant ocular formulations, such as compromised bioavailability and constraints in traversing the corneal barrier. This systematic review endeavours to comprehensively examine the contemporary landscape of research in this domain, focusing on the nuanced capabilities of in situ gelling systems to optimize drug delivery and enhance therapeutic outcomes, without much technological complexity. Employing a meticulous search strategy across diverse databases for publications and patents spanning the years 2015 to 2023 a total of 26 research papers and 14 patents meeting stringent inclusion criteria were identified. Synthesizing the collective insights derived from these investigations, it becomes evident that in situ gelling systems confer an ability to protract the residence time of formulations or active pharmaceutical ingredients (APIs) within the ocular milieu. This sustained presence engenders extended drug release kinetics, thereby fostering improved patient compliance and mitigating the proclivity for side effects attendant to frequent dosing. These salutary effects extend to diminished systemic drug absorption, augmented ocular bioavailability, and the prospect of reduced dosing frequencies, thereby amplifying patient adherence to therapeutic regimens. Intriguingly, the protective attributes of in situ gelling systems extend to the establishment of an ocular surface barrier, thereby abating the susceptibility to infections and inflammatory responses. In summation, this review underscores the auspicious potential of in situ gelling systems as a transformative approach to advancing ocular drug delivery, warranting sustained research endeavours and developmental initiatives for the betterment of global patient outcomes.

Magnetic targeting of lornoxicam/SPION bilosomes loaded in a thermosensitive in situ hydrogel system for the management of osteoarthritis: Optimization, in vitro, ex vivo, and in vivo studies in rat model via modulation of RANKL/OPG

Osteoarthritis is a bone and joint condition characterized pathologically by articular cartilage degenerative damage and can develop into a devastating and permanently disabling disorder. This investigation aimed to formulate the anti-inflammatory drug lornoxicam (LOR) into bile salt-enriched vesicles loaded in an in situ forming hydrogel as a potential local treatment of osteoarthritis. This was achieved by formulating LOR-loaded bilosomes that are also loaded with superparamagnetic iron oxide nanoparticles (SPIONs) for intra-muscular (IM) administration to improve joint targeting and localization by applying an external magnet to the joint. A 31.22 full factorial design was employed to develop the bilosomal dispersions and the optimized formula including SPION (LSB) was loaded into a thermosensitive hydrogel. Moreover, in vivo evaluation revealed that the IM administration of LSB combined with the application of an external magnet to the joint reversed carrageen-induced suppression in motor activity and osteoprotegerin by significantly reducing the elevations in mitogen-activated protein kinases, extracellular signal-regulated kinase, and receptor activator of nuclear factor kappa beta/osteoprotegerin expressions. In addition, the histopathological evaluation of knee joint tissues showed a remarkable improvement in the injured joint tissues. The results proved that the developed LSB could be a promising IM drug delivery system for osteoarthritis management.

Phase transforming in situ gels for sustained and controlled transmucosal drug delivery via the intravaginal route

Direct, reliable, controlled, and sustained drug delivery to female reproductive tract (FRT) remains elusive, with conventional dosage forms falling way short of the mark, leading to premature leakage, erratic drug delivery, and loss of compliance. Historically, the intravaginal route remains underserved by the pharmaceutical sector. To comprehensively address this, we turned our focus to phase-transforming sol-gels, using poloxamers, a thermosensitive polymer and, doxycycline (as hyclate salt, DOXH) as our model agent given its potential use in sexually transmitted infections (STIs). We further enhanced mucoadhesiveness through screening of differing viscosity grade hydroxypropyl methyl celluloses (HPMCs). The optimised sol-gels remained gelled at body temperature (<37 °C) and were prepared in buffer aligned to vaginal cavity pH and osmolality. Lead formulations were progressed based on their ability to retain key rheological properties, and acidic pH in the presence of simulated vaginal fluid (SVF). From a shelf-life perspective, DOXH stability, gelation temperature (Tsol-gel), and pH to three months (2-8 °C) was attained. In summary, the meticulously engineered, phase-transforming sol-gels provided sustained mucoretention despite dilution by vaginal fluid, paving the way for localised antimicrobial drug delivery at concentrations that potentially far exceed the minimum inhibitory concentration (MIC) for target STI-causing bacteria of the FRT.

Design and Evaluation of a Dual-Sensitive In Situ Gel for the Controlled Release of Pranoprofen

Currently, the marketed ophthalmic preparations of pranoprofen (PF) are mainly eye drops, but due to the special clearance mechanism of the eye and corneal reflex, the contact time between the drug and the focal site is short, most of the drug is lost, and the bioavailability is less than 5%. In the present study, an in situ gel eye drop containing no bacteriostatic agent and sensitive to temperature and ions was designed for delivery of PF. It was demonstrated to meet the criteria for ophthalmic preparations by characterization such as appearance content sterility. Ocular irritation tests showed a favorable safety profile. In vivo ocular retention time experiments showed that the ocular retention time of the pranoprofen gel was 4.41 times longer than that of commercially available drops (Pranopulin®), and the nasal tear excretion of the pranoprofen gel was lower than that of Pranopulin®, which suggests that the drug loss was reduced relative to that of the drops. The efficacy of the pranoprofen gel against tincture of cayenne pepper-induced corneal and conjunctival inflammation was examined using Pranopulin® as a control and in conjunction with inflammation scores, H&E slice results, and levels of IL-1β, IL-6, and TNF-α. The results showed that pranoprofen gel and Pranololin® had significant efficacy in the treatment of corneal and conjunctival inflammation, and the anti-inflammatory effect of pranoprofen gel was superior to that of Pranololin®. This study provides a new option for the treatment of corneal and conjunctival inflammation.

Poloxamer sols endowed with in-situ gelability and mucoadhesion by adding hypromellose and hyaluronan for prolonging corneal retention and drug delivery

The purpose of this study was to develop poloxamer (P407)-based in-situ thermogellable hydrogels with reducing concentration of P407 by adding hypromellose (HPMC) and with enhancing mucoadhesion of resulting hydrogels by adding hyaluronic acid (HA) for prolonging ocular delivery of hydroxypropyl-β-cyclodextrin (HPβCD)-solubilized testosterone (TES). Results demonstrated that 0.5% TES solution was successfully solubilized with adding 10% HPβCD. Non-gellable 13% P407 sol became in-situ gellable with adding 2.0-2.5% HPMC and mucoadhesibility was further imporved with adding 0.3% HA-L (low MW) or HA-H (high MW). Optimized 0.5% HPβCD-solubilized TES P407-based thermogellable hydrogels with enhancement of mucoadhesion for prolonging ocular delivery comprised 13% P407, 2.5% HPMC, and 0.3% HA-L or HA-H. Furthermore, rheological measurements under simulated eye blinking confirmed that non-thixotropic properties of optimized hydrogels could be spreaded evenly and retain a greater amount of drug-loaded hydrogels on the ocular surface for a longer period to prolong drug delivery. Compared with conventional eye drops, the prolonged residence time of optimized hydrogels from ex vivo and in vivo studies were observed, indicating relationships between rheological properties and in vivo performances. It was concluded that P407-based thermosensitive hydrogels with reducing concentration of P407 and enhancing mucoadhesion was successfully formulated by adding 2.5% HPMC and 0.3% HA in 13% P407 for potentially accomplishing effective clinical treatment of DED.

Tacrolimus-Loaded Cationic Nanoemulsion In-Situ Gel System: In-Vitro Characterization and Performance in a Dry-Eye Rabbit Model

Dry eye disease (DED) is a highly prevalent ocular surface disease that affects life quality and reduces productivity at work. The purpose of this study is to improve the efficacy of tacrolimus (FK506) in the treatment of DED using the special eye surface retention properties of cationic nanoemulsion (CNE) modified by thermosensitive in-situ gel (ISG) (CNE-ISG). The precorneal retention of CNE-ISG containing 0.05% FK506 (50 min) was longer than that of CNE containing 0.05% FK506 (25 min) and commercial suspension containing 0.1% FK506 (Talymus®) (10 min). Successfully modeled dry-eye rabbits were treated with 0.05% CNE-ISG (twice/day), 0.05% CNE and 0.1% suspension (Talymus®) (thrice/day). Schirmer's tear secretion test showed no significant difference between the CNE-ISG group and the healthy group after 5 days of treatment (p > 0.05). The results of a tear ferning test (TFT) showed that the tear-fern-like crystal branches in the CNE-ISG group returned to normal after 5 days of treatment. Histological analysis showed that the number of goblet cells in the CNE-ISG group significantly increased. HET-CAM stimulation test showed that the CNE-ISG group had no ocular irritation. The above results indicated that CNE-ISG might be a promising delivery system and as an effective dosage form was employed for FK506 in the treatment of DED.

Factors affecting on in vitro release of miconazole from in situ ocular gel

The reason for conducting this study is to prolong release of miconazole in the ocular site of action by ocular-based gels (OBGs) formulations. The formulation factors affecting on the release from OBG should be studied using various gelling agents in various concentrations to achieve the improvement in retention and residence time in response to prolonged release. In this study, the formulations were prepared using carbopol 940, pectin, sodium alginate, poloxamer 407, and poly(methacrylic acid) at 0.5%, 1%, and 1.5% w/v, respectively. Hydroxypropyl methylcellulose E5 (HPMC E5) 1% was added as thickening agent/viscosity builder. The formulation containing carbopol 940, pectin and sodium alginate at 1.5% w/v, displayed a noticable improvement in viscosity, gelling capacity, and extended release for 7 h in comparison with the reference drug. Overall, the release showed that the sodium alginate with HPMC E5 form in situ gel which had longer time of release reach to 12 h compared with other polymers. the release of miconazole from the OBGs affected significantly by two factors includes gelling capacity and viscosity builder. The novelty of this study is supporting the delivery of ocular drugs through a cornea as an important key of the eye instead of dependence on an internal blood supply using an oral or a parental administration.

Hot-melt extruded in situ gelling systems (MeltDrops Technology): Formulation development, in silico modelling and in vivo studies

In situ gelling systems (ISGS) can prolong retention time and bioavailability of ophthalmic solutions. The complexity and cost of ISGS avert their industrial scale-up and clinical implementation. In this study, we demonstrate novel application of hot-melt extrusion (HME) technology for continuous manufacturing of ISGS (MeltDrops Technology). Timolol maleate (TIM) and dorzolamide hydrochloride (DRZ) loaded MeltDrops were successfully developed using HME for glaucoma management, thereby resolving issues with batch manufacturing of ISGS, prolonging retention time thus improving bioavailability. The MeltDrops technology involves one-step, i.e., passing all the ingredients through an extruder at a screw speed between 20-50 rpm and barrel temperature of 80 °C. The comparative evaluation of MeltDrops and batch-processed ISGS demonstrated that MeltDrops exhibited better physical and chemical content uniformity. The extrusion temperature and screw speed were critical factors influencing content uniformity and properties of the MeltDrops. MeltDrops showed sustained drug release for >12 hours in vitro (TIM= 83.07%; DRZ = 60.43%, 12hours) versus marketed eyedrops. The developed MeltDrops followed Peppas-Sahlin model, combining Fickian diffusion and swelling processes. The in vivo study in New Zealand rabbits revealed superior effectiveness and safety of the MeltDrops as compared to the marketed eyedrops. Herein we conclude, MeltDrops would serve as a cutting-edge platform technology that can be used to manufacture various ISGS with one-step processability, cost-effectiveness, and improved product quality, which are otherwise processed by batch manufacturing that involves numerous complex processing steps.

Bentonite-in hypromellose-poloxamer sol-gel for corneal application of trimetazidine: Study of rheology and ocular anti inflammatory potential

Bentonite is reported to be used for extending ocular drug delivery safely in a controlled manner. Bentonite combined hydroxypropyl methylcellulose (HPMC)-poloxamer based sol-to-gel formulation has been developed for the prophylactic ocular anti-inflammatory effect of trimetazidine after corneal application. HPMC-poloxamer sol formulation was prepared incorporating trimetazidine to bentonite at 1: 2*10^-5 to 1:5*10^-6 ratios using cold method, and investigations were carried out in carrageenan-induced rabbit eye model. Pseudoplastic shear thinning behavior without any yield value and high viscosity at low shear rate were the positive attribute of the tolerability of the sol formulation after ocular instillation. Presence of bentonite nanoplatelets revealed more sustained in vitro release (~79-97 %) and corneal permeation (~79-83 %) over a period of 6 h in comparison to its absence. Prominent acute inflammation has been produced in the carrageenan-induced untreated eye, whereas the absence of ocular inflammation has been noticed in the previously sol-treated eye even after carrageenan injection. HPMC-poloxamer-based formulation exhibited stronger binding affinity (5.13 kcal/mol) in the presence of bentonite rather than its absence (3.99 kcal/mol), resulting in a stable and sustained effect. HPMC-poloxamer in-situ gel of trimetazidine containing bentonite could be utilized for sustained ocular delivery and the control of ophthalmic inflammation prophylactically.

Optimization and in vivo evaluation of triamcinolone acetonide loaded in situ gel prepared using reacted tamarind seed xyloglucan and kappa-carrageenan for ocular delivery

In the current work, triamcinolone acetonide (TAA) loaded dual responsive in situ gelling system was designed and optimized using reacted tamarind seed xyloglucan (RXG) (thermoresponsive) and kappa-Carrageenan (κ-CRG) (ion-sensitive) polymers. Tamarind seed xyloglucan (TSX) was subjected to purification followed by enzymatic treatment to produce RXG with ~40 % reduction in galactose content compared to TSX. RXG was characterized using size exclusion chromatography, Fourier transform infrared and proton nuclear magnetic resonance spectroscopy to confirm the ~40 % reduction in galactoside content compared to TSX. The proportions of RXG and κ-CRG in the in situ gels (TAA loaded RXG-κ-CRG) were optimized based on their rheological properties. The optimized in situ gel exhibited good flow properties at 25 °C, but transformed rapidly into a stronger gel in the presence of STF at 35 °C. The optimized formulation had strong mucoadhesion with good spreadability on the surface of excised goat cornea. The drug release followed zero-order kinetics from the optimized in situ gel. Ex vivo ocular toxicity studies indicate that the optimized formulation was well tolerated. The ocular pharmacokinetic studies in rabbits showed significantly higher and sustained vitreous humor exposure of TAA for optimized in situ gel compared to hydroxypropyl-β-cyclodextrin based aqueous suspension of TAA.

Thermoreversible Carbamazepine In Situ Gel for Intranasal Delivery: Development and In Vitro, Ex Vivo Evaluation

Over the past decade, intranasal (IN) delivery has been gaining attention as an alternative approach to conventional drug delivery routes targeting the brain. Carbamazepine (CBZ) is available as an orally ingestible formulation. The present study aims to develop a thermoreversible in situ gelling system for delivering CBZ via IN route. A cold method of synthesis has been used to tailor and optimize the thermoreversible gel composition, using poloxamer 407 (P407) (15-20% w/v) and iota carrageenan (ɩ-Cg) (0.15-0.25% w/v). The developed in situ gel showed gelation temperatures (28-33°C), pH (4.5-6.5), rheological properties (pseudoplastic, shear thinning), and mucoadhesive strength (1755.78-2495.05 dyne/cm²). The in vitro release study has shown sustained release behavior (24 h) for gel, containing significant retardation of CBZ release. The release kinetics fit to the Korsmeyer-Peppas model, suggesting the non-Fickian diffusion type controlled release behavior. Ex vivo permeation through goat nasal mucosa showed sustained release from the gel containing 18% P407 with the highest cumulative drug permeated (243.94 µg/cm²) and a permeation flux of 10.16 µg/cm²/h. After treatment with CBZ in situ gel, the barrier function of nasal mucosa remained unaffected. Permeation through goat nasal mucosa using in situ gel has demonstrated a harmless nasal delivery, which can provide a new dimension to deliver CBZ directly to the brain bypassing the blood-brain barrier.

Deoxycholic acid-chitosan coated liposomes combined with in situ colonic gel enhances renal fibrosis therapy of emodin

BACKGROUND

Renal fibrosis is the final common pathological feature of various chronic kidney diseases (CKD). Despite recent advances, development of new treatments strategy is needed. Emodin (EMO), an important ingredient of Chinese medicine, rhubarb (Polygonaceae Rheum palmatum l.), has been reported to inhibit the development of renal fibrosis effectively. However, the poor oral bioavailability of EMO and the insufficient monotherapy therapy compromise its efficacy.

PURPOSE

In order to enhance renal fibrosis therapy of emodin, an innovative combination therapy based on deoxycholic acid-chitosan coated liposomes (DCS-Lips) and in situ colonic gel (IGE) was developed.

METHODS

For one, the DCS-Lips were prepared via electrostatic interaction by mixing anionic conventional Lips with cationic DCS, deoxycholic acid conjugated on the backbone of chitosan. The cellular uptake of FITC-labeled DCS-Lips in Caco-2 cell monolayer was evaluated by CLSM and flow cytometry, respectively. Permeability study was carried out using Caco-2 cell monolayer. For another, EMO-loaded in situ colonic gel (EMO-IGE) was prepared by mixing EMO nanosuspensions and plain in situ gel, which was obtained by the cold method. The EMO-IGE was assessed for morphology, gelation temperature, viscosity and in vitro drug release. Finally, the therapeutic efficacy of the combination strategy, oral DCS-Lips formulations and in situ colonic gel, was evaluated in unilateral ureteral obstruction (UUO) rat model. Additionally, 16S rDNA sequencing was performed on rats faces to investigate whether the combination strategy improves the microbial dysbiosis in UUO rats.

RESULTS

The prepared DCS-Lips produced small, uniformly sized nanoparticles, and significantly enhanced the cellular uptake and in vitro permeability of EMO compared to non-coated liposomes. Moreover, the EMO-IGE was characterized by short gelation time, optimal gelling temperature, and excellent viscosity. In UUO model, the combination of DCS-Lips (gavage) and IGE (enema) attenuated renal fibrosis effectively. The results of 16S rDNA sequencing illustrated that IGE could restore the gut microbial dysbiosis of UUO rats.

CONCLUSION

Overall, the combination of DCS-Lips and EMO-IGE alleviated renal fibrosis effectively, resulting from the improved oral bioavailability of EMO by DCS-Lips and the restoration of gut microbiota by EMO-IGE, thus, presenting an innovative and promising potential for renal fibrosis treatment.

A state-of-the-art review on the recent advances of niosomes as a targeted drug delivery system

The buildup of nonionic surfactants in the aqueous environment produces niosomes. The usage of niosomes is becoming increasingly frequent due to their sustainability, low cost of components and assembly, large-scale manufacture, and, finally, easy maintenance of the niosomes to the other. Because of their nonionic characteristics, niosomes play a critical role in medication delivery systems. Controlled release and targeted distribution of niosomes to treat cancer, infectious illnesses, and other disorders are one of their most important properties. Niosomes can also be injected by ocular and transdermal routes, which are less common than oral and parenteral administration. Using niosomes to manufacture biotechnology goods and novel vaccines is one of the most exciting research fields today. The molecular structure of niosomes, the physicochemical characteristics of nonionic surfactants in their formulation, the influence of external stimuli on niosomes, the many methods of niosomes administration, and their diverse therapeutic qualities are all explored in this study.

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.

Self-Assembling Drug Formulations with Tunable Permeability and Biodegradability

This review focuses on key topics in the field of drug delivery related to the design of nanocarriers answering the biomedicine criteria, including biocompatibility, biodegradability, low toxicity, and the ability to overcome biological barriers. For these reasons, much attention is paid to the amphiphile-based carriers composed of natural building blocks, lipids, and their structural analogues and synthetic surfactants that are capable of self-assembly with the formation of a variety of supramolecular aggregates. The latter are dynamic structures that can be used as nanocontainers for hydrophobic drugs to increase their solubility and bioavailability. In this section, biodegradable cationic surfactants bearing cleavable fragments are discussed, with ester- and carbamate-containing analogs, as well as amino acid derivatives received special attention. Drug delivery through the biological barriers is a challenging task, which is highlighted by the example of transdermal method of drug administration. In this paper, nonionic surfactants are primarily discussed, including their application for the fabrication of nanocarriers, their surfactant-skin interactions, the mechanisms of modulating their permeability, and the factors controlling drug encapsulation, release, and targeted delivery. Different types of nanocarriers are covered, including niosomes, transfersomes, invasomes and chitosomes, with their morphological specificity, beneficial characteristics and limitations discussed.

Gel-Based Materials for Ophthalmic Drug Delivery

The most common route of administration of ophthalmic drugs is the topical route because it is convenient, non-invasive, and accessible to all patients. Unfortunately, drugs administered topically are not able to reach effective concentrations. Moreover, their bioavailability must be improved to decrease the frequency of administrations and their side effects, and to increase their therapeutic efficiency. For this purpose, in recent decades, particular attention has been given to the possibility of developing prolonged-release forms that are able to increase the precorneal residence time and decrease the loss of the drug due to tearing. Among these forms, gel-based materials have been studied as an ideal delivery system because they are an extremely versatile class with numerous prospective applications in ophthalmology. These materials are used in gel eye drops, in situ gelling formulations, intravitreal injections, and therapeutic contact lenses. This review is intended to describe gel-based materials and their main applications in ophthalmology.

Repurposing of nifedipine loaded in situ ophthalmic gel as a novel approach for glaucoma treatment

Glaucoma is a chronic eye disease characterized by elevated intraocular pressure (IOP) which causes severe complications to the eyes and may lead to vision loss. The effective treatment of such diseases motivated the search for novel and unique drugs and delivery systems. It has been reported that, nifedipine (NF) is effective in reducing the elevated IOP due to vasodilatation of eye vascular smooth muscles. NF loaded thermo-sensitive in situ gels were prepared by the cold method using poloxamer 407 (P407) and hydroxypropyl methyl cellulose (HPMC) polymers adopting Box-Behnken experimental design. All the prepared formulae were tested for homogeneity, clarity, pH, isotonicity, gelling capacity, rheological behavior, in vitro drug release and were tested in vivo on rabbits. The prepared in situ gels were homogenous, transparent, having a pH ranged from 5 to 5.5 and undergo sol-gel transition within few seconds physiological temperature. The in situ gels showed sustained in vitro release of NF where about 76% of the loaded drug was released over 12 h. NF loaded in situ gels showed a 45.83 ± 2.91% reduction in the IOP, with no sign of toxicity or irritation to the eye in rabbits. The current investigations clarified the efficiency of this novel and unique NF loaded in situ gel for the control of the IOP compared to the conventional ophthalmic dosage forms.

Betaxolol-loaded niosomes integrated within pH-sensitive in situ forming gel for management of glaucoma

Blindness and impaired vision are considered as the most troublesome health conditions leading to significant socioeconomic strains. The current study focuses on development of nanoparticulate systems (i.e., niosomes) as drug vehicles to enhance the ocular availability of betaxolol hydrochloride for management of glaucoma. Betaxolol-loaded niosomes were further laden into pH-responsive in situ forming gels to further extend precorneal retention of the drug. The niosomes were evaluated in terms of vesicle size, morphology, size distribution, surface charge and encapsulation efficiency. The optimized niosomes, comprised of Span® 40 and cholesterol at a molar ratio of 4:1, displayed particle size of 332 ± 7 nm, zeta potential of -46 ± 1 mV, and encapsulation efficiency of 69 ± 5%. The optimal nanodispersion was then incorporated into a pH-triggered in situ forming gel comprised of Carbopol® 934P and hydroxyethyl cellulose. The formed gels were translucent, pseudoplastic, mucoadhesive, and displayed a sustained in vitro drug release pattern. Upon instillation of the betaxolol-loaded niosomal gel into rabbits' eyes, a prolonged intraocular pressure reduction and significant enhancement in the relative bioavailability of betaxolol (280 and 254.7%) in normal and glaucomatous rabbits, were attained compared to the marketed eye drops, respectively. Hence, the developed pH-triggered nanoparticulate gelling system might provide a promising carrier for ophthalmic drug delivery and for improved augmentation of glaucoma.