This article offers a comprehensive review of nanotechnology-based treatments for patients with glaucoma. |
Nanotechnology-based drugs will probably be incorporated into the arsenal of glaucoma specialists in the near future, allowing benefits such as reduced side effects, and less frequent dosing, among others. |
Toxicity issues related to nanotechnology-based treatments have yet to be addressed to test their safety. |
Further human studies in nanomedicine for glaucoma treatment are needed until this promising pharmacological innovation becomes available in the ophthalmologist’s daily therapeutic practice. |
Introduction
Targeting Intraocular Pressure Reduction
Drug Delivery Routes, Features, and Limitations of Current Glaucoma Medical Therapy
Role and Value of Nanoparticles
Emergence of Nanomedicine Formulations in Glaucoma
Pilocarpine
Hypotensive drug/nanosystem | Pharmaceutical form | Study design/model | Results | References |
---|---|---|---|---|
Complex of pilocarpine prodrug, O,O′-dipropionyl-(1,4-xylylene) bispilocarpate, with various β-cyclodextrin derivatives | Cyclodextrin | Experimental/pigmented rabbits | Ocular irritation caused by pilocarpine prodrug is eliminated with viscous SBE7-β-CyD solution without compromising the ocular absorption of the prodrug | [78] |
Poly(amidoamine) (PAMAM) dendrimers (with primary amino (G2, G4), hydroxyl (G2(OH), G4(OH)), and carboxylate (G1.5, G3.5) surface groups | Dendrimers | Experimental/New Zealand albino rabbits | Intensity of pilocarpine’s pharmacological activity associated with G1.5 and G4(OH) dendrimer solutions was reported to be superior | [79] |
Pilocarpine HCl encapsulated neutral and negatively charged multilamellar vesicles (MLVs) | Liposomes | Experimental/pigmented rabbits | Neutral MLVs lowered the IOP from 20.7 to 15 mmHg for 4–5 h Negatively charged MLVs decreased the IOP for a shorter period of time (~ 1 h), which was similar to the free drug | [80] |
Pilocarpine nitrate–cyclodextrin complex | Cyclodextrin | In vitro permeability study using isolated excised corneas of albino rabbits | HP-β-CD promoted an increase in the corneal permeability of pilocarpine nitrate (permeability coefficient = 6.38 × 10−5 ± 2.82 × 10−7 cm/s, compared to 1.67 × 10−5 ± 2.12 × 10−7 cm/s with neat pilocarpine nitrate) | [81] |
Pilocarpine-loaded poly(ε-caprolactone) (PCL) nanocapsules (PILO-PCL NCs) and pilocarpine-loaded PCL nanospheres (PILO-PCL NSs) | Nanocapsules and nanospheres | In vitro pilocarpine cumulative release studies, and in vivo studies (glaucomatous rabbit eyes intracamerally injected with PILO-PCL NSs or PILO-PCL NCs) | Pilocarpine loading capacity of PCL NCs was nearly 3 times greater than that in PILO-PCL NSs. PILO-PCL NC-treated group reduced IOP for the entire period of the study (42 days), exhibiting a sustained drug release profile | [82] |
Pilocarpine-loaded hydrogels (three different hydrogels containing l-valine residues, HVa) | Hydrogels | In vitro pilocarpine release and its effect on cell proliferation Cytotoxicity experiments with mouse immortalized fibroblast NIH3T3 cells Cell viability, after 24 h of incubation with the native and pilocarpine-loaded hydrogel | Pilocarpine-loaded in HVa hydrogels showed a 3 times greater releasing profile | [83] |
Hydrogels were non-toxic to the mouse fibroblast NIH3T3 cells | ||||
Cell proliferation was increased with the presence of pilocarpine, even after 2 days | ||||
Pilocarpine nitrate-loaded liquid crystal nanoparticles (PN-loaded LCNPs) | Liquid crystal nanoparticles | In vitro release profile of PN | Maximum decrease in IOP was 41.93 ± 16.79% with the commercial drug (peak effect at 2 h), versus 59.21 ± 7.04% (peak after 5 h) with PN-LCNPs | [84] |
Ex vivo penetration study (freshly excised albino rabbit cornea) | Ex vivo drug penetration study demonstrated that the amount of PN penetration across the cornea at 1 h was 0.54 ± 0.20 µg with PN-LCNPs and 0.12 ± 0.06 µg with PN solution | |||
Pilocarpine hydrochloride-loaded nanocomposite formulations (cellulose nanocrystals and triblock poloxamer copolymer) | Hydrogel/nanocrystals | In vivo IOP measurements using an indentation tonometer | In vitro release of pilocarpine hydrochloride from the nanocomposite hydrogels was extended compared to the pure poloxamer gel | [85] |
In vitro drug release analysis and toxicity assay of in vitro gel | The greater the concentration of cellulose nanocrystals, the higher the sustained drug release property of the nanocomposite hydrogels | |||
Nanocomposite formulation exhibited non-toxic behavior | ||||
Pilocarpine-loaded chitosan/Carbopol nanoparticle ophthalmic Formulation | Hydrogel | In vitro release profile | In vitro analysis showed that nanoparticles displayed the best sustained release profile for 24 h compared to the other 3 formulations | [86] |
In vivo (albino rabbits) miotic effect of pilocarpine chitosan/Carbopol nanoparticles was compared with various pilocarpine formulations (traditional eye drops, gels, and liposomes) | In vivo study showed extended miosis of pilocarpine-loaded chitosan/Carbopol nanoparticles, which was superior to those of liposomes, pilocarpine gel, and pilocarpine drops |
Timolol Maleate
Hypotensive drug/nanosystem | Pharmaceutical form | Study design/model | Results | References |
---|---|---|---|---|
Timolol-loaded gold nanoparticles (GNPs) | Gold nanoparticles | In vitro release study | Maximum timolol concentration for blank contact lenses at 1 h was 581 µg/ml, while in the GNP-laden CLs it was 1685 µg/ml | [90] |
In vivo drug release and pharmacodynamic studies (New Zealand Albino Rabbits) | In the GNP-laden CLs group, IOP decreased by 4 mmHg after 1 h, which progressively increased after 72 h. In the marketed eye drop group, maximum IOP decrease was 3 mmHg after 3 h, which returned to baseline IOP after 12 h | |||
Ocular tissue distribution study | Analysis of the rabbit tear fluid showed higher timolol concentrations with the GNP-CLs at all time points | |||
GNPs were incorporated into contact lenses (CLs) | After 24 h of GNP-laden CL wear, a twofold and a fourfold increase in the timolol concentration in the conjunctiva and in the iris-ciliary muscle occurred, respectively | |||
Timolol maleate/gelatin nanoparticle conjugate | Hydrogel | Experimental/New Zealand albino rabbits | The average 24-h IOP reduction was 52%, compared to 31% provided by regular timolol eye drops | [91] |
Timolol-loaded nanoparticles into a poly(hydroxyl ethyl methacrylate) (p-HEMA) matrix | Hydrogel | In vitro drug release experiments | The higher the amount of nanoparticles in the HEMA, the higher the rate of drug release (particle to HEMA ratio 25:75 provided a total release at 95 °C of 283.08 ± 4.48 µg; particle to HEMA ratio 100:0 provided a total release at 95 °C of 743.27 ± 25.40 µg, and also increased the release duration) | [92] |
Timolol-loaded multilamellar vesicles (MLVs) | Liposomes | Experimental/New Zealand albino rabbits | Positively charged MLVs of multilamellar liposomes provided a sustained IOP reduction for more than 24 h (which extended for about 1 week), whereas the free drug lowered IOP for 4 h | [93] |
Chitosan (REVTMbio1) or Carbopol (REVTMbio2 and 3) coated niosomal timolol maleate (0.25%) | Niosomes | In vitro release pattern of niosomal preparations | Peak effect of IOP reduction with marketed formulation was at 2 h, compared to 3 h with all the REVTMbio formulations. However, chitosan-coated vesicles (REVTMbio1) showed an effect sustained for up to 8 h, compared to the marketed formulation, whose effect lasted for 5 h. REVTMbio1 formulation containing 0.25% timolol maleate showed similar effect compared to 0.5% marketed gel formulation | [94] |
Timolol maleate entrapped in PVA or PCL nanofibers | Biodegradable polymeric nanofibers | In vitro drug release studies and in vivo studies (New Zealand albino rabbits) | Nanofibers were capable of controlled drug delivery for up to 24 h | [95] |
Nanofiber formulation showed a significant IOP reduction for 72 h, while the marketed formulation kept the IOP reduced for 4 h | ||||
Chitosan-coated timolol maleate (TM) mucoadhesive film | Hydrogel | In vitro drug release studies and in vivo studies (New Zealand albino rabbits) | In vitro study showed that 85% of timolol was released from the mucoadhesive films in 2 weeks, and the total content was released within 4 weeks | [96] |
IOP-lowering efficacy of the 0.5% TM commercial ophthalmic solution was similar to the films. However, animals that received TM-loaded chitosan films kept their IOP at lower levels over a 10-week period, while the effect of the timolol commercial eye drops group was maintained for 12 days | ||||
Nanoencapsulation of timolol in neat chitosan (CS) and N-alkylated chitosans [chitosan derivatives with succinic anhydride (CSUC) and 2-carboxybenzaldehyde (CBCS)] | Hydrogel | In vitro drug release study | In the majority of nanoparticles formulations, timolol is entrapped in amorphous form, but the present study, using different diameters of nanoparticles and CS and two N-acylated derivatives of CS as carriers, proved that drug entrapment efficiency was higher in CBCS derivative. Different timolol release rates among the tested formulations ratified that they vary according to specific carrier, nanoparticle size, and drug loading | [97] |
Timolol maleate encapsulated in PLGA/PLA microspheres | Microspheres | In vitro drug release study | PLGA 502H:PLA blended microspheres released 30% of their timolol maleate content after 1 day. However, the remaining drug was released in a sustained manner over 107 days | [98] |
Timolol-loaded chitosan–sodium alginate (CS-SA blend) nanoparticles | Hydrogel | In vitro drug release study | In vitro release from the CS-SA nanoparticles showed a burst of about 20% within the first hour and 35% of timolol was released after a period of 5 h, demonstrating that it may be released from synthesized particles in a sustained mode | [99] |
Timolol maleate chitosan coated liposomes (TM-CHL) | Liposomes | In vitro drug release study | TM-CHL produced a 3.18-fold increase in the corneal permeation coefficient | [100] |
In vivo transcorneal permeation studies (New Zealand rabbits) | TM-CHL was more effective in lowering IOP than timolol eye drops (final IOP = 19.67 ± 1.14 mmHg versus 23.80 ± 1.49 mmHg, respectively) | |||
Timolol liposomes (TLP), and TLP with 0.02% Trancutol P (TLPG) | Liposomal hydrogel | In vitro transcorneal permeation study In vivo pharmacodynamics (New Zealand and pigmented glaucomatous rabbits) | Timolol–liposome system showed a transcorneal penetration 1.50-fold higher than that of the marketed eye drop, while the addition of Trancutol P enhanced it 2.19 times Timolol liposomal gel showed superior IOP reduction compared with Timolol eye drops at each time point | [101] |
Timolol maleate-loaded galactosylated chitosan nanoparticles | Hydrogel | In vitro release study | Timolol maleate-loaded galactosylated chitosan nanoparticles showed an initial burst release of 91% in 8 h and had a sustained release compared with the commercial timolol eye drops | [102] |
In vitro transcorneal permeation study | Preocular retention of timolol maleate-loaded galactosylated chitosan nanoparticles was longer than that of timolol eye drops | |||
Preocular retention study | IOP-lowering effect of timolol maleate-loaded galactosylated chitosan nanoparticles reached 10.5 ± 0.51 mmHg 4 h after instillation, while the peak effect of the commercial eye drops was 6.8 ± 0.35 mmHg at 3 h | |||
In vivo pharmacodynamics study (albino rabbits) | IOP-lowering effect of timolol maleate-loaded galactosylated chitosan nanoparticles continued for up to 12 h, while the effect of commercial eye drops ceased after 8 h | |||
Timolol-loaded liposome incorporated ion-sensitive in situ gels | Liposomes | In vitro release studies | Timolol-loaded liposome formulations showed a 1.93-fold increase in permeability coefficients | [103] |
Deacetylated gellan gum | Pharmacodynamics study (measurement of intraocular pressure in normal albino rabbits and in ocular hypotensive rabbits) | Timolol-loaded liposome formulations reduced IOP from 30 to 300 min after instillation (minimum IOP = 11.96 ± 0.74 mmHg at 1 h), while the IOP decreased from 30 to 180 min (minimum IOP = 13.61 ± 0.95 mmHg at 2 h) with timolol eye drops |
Carbonic Anhydrase Inhibitors
Acetazolamide
Hypotensive drug/nanosystem | Pharmaceutical form | Study design/model | Results | References |
---|---|---|---|---|
Eudragit nanoparticles (NPs) of ACZ incorporated into an ocular insert | Eudragit nanoparticles | In vitro drug diffusion study Ex vivo transcorneal permeability study (excised fresh goat corneas) In vivo ocular tolerability and IOP reduction study (albino rabbits): animals received drinking water (40 ml/kg of body weight of rabbit) to increase IOP 3 groups: (1) ACZ reference solution, (2) Eudragit NPs dispersion, and (3) ocular insert of Eudragit NPs | Ex vivo transcorneal permeation study showed the following results. Flow across corneal tissue (µg/min): drug suspension. 0.671 ± 0.020; NPs suspension. 2.460 ± 0.028; ocular insert, 2.402 ± 0.032, which means that ACZ-loaded Eudragit NPs displayed better permeability and flow across corneal tissue than the drug suspension In vivo studies with optimized ACZ loaded Eudragit NPs and ocular insert demonstrated substantial IOP lowering and improved ocular tolerability when compared to ACZ suspension | [125] |
ACZ-loaded nanoparticulate in situ gels (NP-ISG) | Polymeric nanoparticles with Eudragit RL100, Eudragit RS100, or poly(lactide-co-glycolide) 75:25 (PLGA) | Ex vivo transcorneal permeability study (fresh goat cornea) | Ex vivo transcorneal permeation study displayed higher ACZ permeation at 8 h with NP10 (93.5 ± 2.25 mg/cm2) and with NP-ISG5 (74.50 ± 2.20 mg/cm2) than with ACZ eye drops (20.08 ± 3.12 mg/cm2) and ACZ suspension (16.03 ± 2.14 mg/cm2) | [126] |
Ex vivo corneal toxicity study (fresh goat cornea) | NP-ISG did not display harmful effects on any corneal layer | |||
In vivo pharmacodynamic activity study (normotensive rabbit) | 1% ACZ nanoparticulate in situ gel exhibited greater IOP-lowering effect 1 h after administration, which was sustained for up to 8 h, while 1% ACZ eye drops only sustained its action for approximately 2 h | |||
ACZ-loaded water-soluble mucoadhesive carbosilane dendrimers | C–Si backbone (carbosilane) cationic dendrimers | In vitro (cytotoxicity and cell viability) investigation (using telomerase-immortalized, human corneal-limbal epithelial cell line, HCLE) | Generations 1 and 2 of the cationic dendrimers and all 3 generations of the anionic dendrimers were well tolerated at 10 μM, with higher than 80% cell survival for all of them, except for the G3-C (from the 3rd generation of carbosilane cationic dendrimers) | [127] |
In vivo (ocular tolerability) study (normotensive New Zealand rabbits): specular microscopy, slit lamp examination, and IOP measurements | Formulation containing ACZ 0.07% (289.4 mOsm; 5.6 pH; 41.7 mN/m) and G3 cationic carbosilane dendrimers (5 μM) demonstrated the best IOP-lowering effect. It obtained a rapid (1 h post-instillation) and sustained (up to 7 h) hypotensive effect, reaching a peak 22.6% IOP reduction | |||
ACZ-loaded hyper branched poly(propylene imine) (PPI) dendrimers | PPI dendrimers | In vitro drug release studies Ex vivo studies (effect on the morphology of human erythrocytes) In vivo studies (normotensive New Zealand rabbits): determination of ocular irritation index, ocular residence time, IOP reduction (25 µL of dendrimer formulation was administered into the lower cul-de-sac of the eye) | Hemolytic toxicity study showed a slightly higher hemolysis rate of dendrimer formulations (D1 = 4.8%, D2 = 5.6%, D3 = 7.2%) when compared to plain drug (3.3%) and plain 5.0G PPI dendrimer (7.9%) Plain ACZ solution produced IOP reductions up to 2 h after instillation, whereas the dendrimer-based formulation lowered IOP for longer (4 h) | [128] |
ACZ-loaded ion-activated nanoemulsion-based in situ gelling systems using gellan gum polymer alone and in combination with other polymers (xanthan gum, hydroxymethylcellulose, or Carbopol) | Nanoemulsion Gellan gum (in various concentrations: 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, and 0.6%) | In vitro release studies | Optimized formula of ion-induced nanoemulsion-based in situ gels demonstrated a significantly sustained drug release profile | [129] |
In vivo studies: ocular irritation and pharmacodynamic studies in adult male New Zealand albino rabbits | Ocular irritation study revealed no damage to the ocular surface and other parts of the eye Area under the curve of percentage decrease in IOP versus time from 0 to 10 h: nanoemulsion formula = 189.15 ± 10.18; Azopt® = 82.51 ± 7.53, and Cidamex® = 79.77 ± 7.58 | |||
ACZ-loaded Eudragit RL100 nanoparticle suspension (ACZ-E-NPs) | Polymeric nanoparticles with Eudragit RL100 | In vitro drug release study In vivo studies (albino rabbits): Group 1 received 0.5% ACZ solution Group 2 received formulation E3 (drug polymer ratio 1:10; organic aqueous phase ratio 1:4; organic phase acetone) Group 3 received formulation E8 (drug polymer ratio 1:10; organic aqueous phase ratio 1:3; organic phase acetone and ethanol) | Plain solution of ACZ was able to lower the IOP for about 3 h after instillation, whereas ACZ-E-NP solutions showed a greater efficacy (IOP lowering for up to 8 h after instillation). The peak IOP reduction by plain ACZ solution was 2.98 ± 0.11 mmHg at 2 h after topical administration, whereas best ACZ-E-NP formulations (E3 and E8) progressively reduced IOP, peaking at 8 h after instillation (F3 = 5.32 ± 0.07 mmHg; E8 = 5.19 ± 0.06 mmHg; mean ± SD) | [130] |
Dorzolamide
Hypotensive drug/nanosystem | Pharmaceutical form | Study design/model | Results | References |
---|---|---|---|---|
Chitosan (CS) and water-soluble 6-O-carboxymethyl (OCM-CS) derivative of CS nanoparticles (NPs) loaded with DRZ | CS or OCM-CS nanoparticles | In vitro studies (drug release and mucoadhesion of NPs) | IOP peak effect and duration of action were | [135] |
In vivo studies (in normotensive albino rabbits): three groups (OCM-CS NPs, CS NPs, and marketed eye drops) received a single dose followed by IOP measurements (after 30 min of drug administration and then every 1 h over a period of 8 h) | With the commercial formulation: 2.9 mmHg 2 h after instillation, and the effect disappeared after 4 h With the DRZ-loaded OCM-CS NPs: peak effect was seen at 4 h, with an IOP reduction of 2.2 mmHg, and the effect was sustained for 8 h With DRZ-loaded CS NPs: peak effect seen at 3 h; IOP reduction was 1.9 mmHg, and the effect was sustained for 6 h | |||
DRZ/γ-cyclodextrin (γ-CD) (18% w/v) complexes stabilized by hydroxypropyl methylcellulose (HPMC) (0.5% w/v) | Cyclodextrins | In vitro mucoadhesive and permeation studies | DRZ distribution 24 h after topical instillation indicated that it penetrates effectively into the eye, including the posterior segment, while serum DRZ concentrations were very low | [136] |
In vivo (using pigmented rabbits): DRZ microparticle suspension was administered to both eyes. After administration the animals were anesthetized, and a sample of aqueous humor was collected once. Blood samples were also collected at each time point (2, 4, 8, and 24 h) | DRZ-γ-CD suspension provided sustained delivery of DRZ in the aqueous humor for up to 24 h. Commercial DRZ led to concentrations in the aqueous humor near zero 8 h after topical administration. The DRZ concentration in the aqueous humor of eyes treated with 3% (w/v) dorzolamide was 45-fold higher than those obtained after instillation of the other three formulations | |||
DRZ-loaded microparticles | Microparticles | In vitro drug release studies In vivo studies (employing normotensive Dutch belted rabbits) | Subconjunctival injection of DRZ-PEG3-PSA microparticles lowered IOP by up to 4.0 ± 1.5 mmHg, when compared to untreated fellow eyes for 35 days | [137] |
DRZ-loaded microparticles or blank microparticles were administered into the subconjunctival space of the superotemporal region of each eye using a 27-gauge needle | Fluorescein-labeled PEG3-PSA microparticles were detected several days after the injection (at least 42 days), indicating a very long in vivo nanoparticle degradation period | |||
IOP measurements were made after the injection | 2% DRZ eye drops reduced IOP for < 6 h | |||
DRZ-loaded chitosan nanoparticles | In situ gelling polymeric (chitosan) nanoparticles | In vitro release study Ex vivo transcorneal permeability studies (on freshly excised goat cornea) Mucoadhesion study of drug loaded in situ gel In vivo studies (using albino rabbits): ocular tolerance test, and gamma scintigraphy study to access precorneal retention time | Optimized formulation (C2S4) demonstrated, in the ex vivo permeability study, a drug permeation of 35.80% within 2 h, compared to 75.30% with the commercial formulation (DRZ 2% ophthalmic solution) Optimized formulation C2S4 showed appropriate gelling feature with 98.1% entrapment efficiency Gamma scintigraphy study showed long retention time of the proposed formulation in the eye, indicating an improved bioavailability of DRZ | [138] |
DRZ-loaded nanoliposome | Liposomes | DRZ-loaded nanoliposome was administered to 20 patients with ocular hypertension or primary open-angle glaucoma (in both eyes) and were followed up for 28 days IOP (days 0, 14, and 28) was compared between the group that received DRZ-loaded nanoliposome and the group that received the marketed DRZ solution | IOP reduction in the DRZ-loaded nanoliposome group was significantly greater than that seen with the commercially available DRZ formulation group (p < 0.05) IOP lowering recorded at 2 weeks was 23.26 ± 9.24%, and 9.25 ± 5.76% for the DRZ-loaded and the control group, respectively IOP lowering at 4 weeks was 32.60 ± 7.90% and 17.48 ± 7.62% for the DRZ-loaded and the control group, respectively | [139] |
DRZ γ-cyclodextrin (γ-CD) nanoparticle | Cyclodextrins | Self-aggregating γ-CD nanoparticle eye drops containing 3% DRZ were instilled once a day in human eyes, compared with the marketed DRZ instilled three times a day, in a prospective randomized single-masked crossover trial | DRZ nanoparticle eye drops once a day and commercial formulation of dorzolamide 2% three times a day did not show statistically significant differences in terms of efficacy at all time points. Nanoparticle eye drops caused less burning sensation than the marketed solution | [140] |
Brinzolamide
Hypotensive drug/nanosystem | Pharmaceutical form | Study design/model | Results | References |
---|---|---|---|---|
Brinzolamide (BZL)-loaded liquid crystalline nanoparticles (BZL LCNPs) | Liquid crystalline nanoparticles | In vitro release study to measure the release of BZL from LCNPs Ex vivo corneal penetration study (employing New Zealand rabbits) Efficacy study (instillation of one drop of marketed BZL, 1% BZL solution, and BZL LCNPs) | Ex vivo permeability coefficient of BZL LCNPs showed a 3.47-fold increase compared with commercial BZL Two hours after instillation, peak IOP decrease was 47.67 ± 3.58% by BZL LCNPs, and 33.75 ± 4.35% by commercial BZL | [145] |
BZL nanocrystal suspensions (BZL-Npsa) | Nanocrystal | Cellular toxicity assay using human corneal epithelial cells (standard cell viability method) | BZL-Npsa pH 4.5 lowered IOP after 60 min (71.4 ± 5.0%) more efficiently than BZL-Npsa pH 7.4 Polysorbate 80 formulation (51.0 ± 26.3%), and commercial BZL (49.6 ± 16.5%) | [146] |
In vivo studies: to verify IOP reduction following BZL-Npsa in glaucomatous Wistar rats | All the tested formulations and commercial BZL showed mild or no toxicity to the human corneal epithelial cells | |||
Trimethyl lock (TMLo) BZL prodrug nanoparticles | Nanocrystals | Instillation of nano eye drops of BZL prodrug in ocular normotensive Sprague–Dawley rats | TMLo BZL prodrug nano eye drops showed similar efficacy as commercial BZL at 1/5 the molar concentration (5.67 mM TMLo BZL prodrug nano eye drops were as effective as 26.1 mM Azopt™), with no toxic effects to the cornea | [147] |
BZL nanoemulsions (BZL NEs) Seven primary BZL NE combinations were used [variations of four nonionic surfactants (Tyloxapol, Labrasol, Cremophor (RH40), and Brij 35), two oils (Capryol 90 and triacetin), and one co-surfactant (Transcutol P)] The amount of BZL was 0.4% in all formulations | Nanoemulsions | In vitro drug release studies In vivo therapeutic studies (ocular normotensive New Zealand albino rabbits): BZL NEs were instilled, followed by IOP measurements at 30, 60, 120, 180, 240, 300, and 360 min after instillation | BZL NEs displayed a sustained release profile with proper physicochemical characteristics, facilitating BZL penetration into the corneal tissue with lower drug concentrations (0.4% vs 1% with commercial BZL) | [148] |
BZL-hydroxypropyl-cyclodextrin (BZL-HP-β-CD) inclusion complex | Cyclodextrins | In vitro corneal permeability and release studies In vivo study (New Zealand normotensive rabbits): Group A: BZL-HP-β-CD 0.2% inclusion complex; Group B: BZL-HP-β-CD 0.5% inclusion complex; Group C: commercial BZL (1%) IOP measured 30, 60, 120, 150, 180, 240, and 300 min after instillation | In vitro corneal accumulation and permeability of the BZL-HP-β-CD inclusion complex was increased 2.91-fold compared to commercial BZL Solubility of BZL increased 10-fold with the (BZL-HP-β-CD) inclusion complex (BZL-HP-β-CD) inclusion complex (0.5% BZL) showed IOP-lowering efficacy comparable to commercial BZL in vivo | [56] |
Brinzolamide (BZL)-hydropropyl-β-cyclodextrin (HP-β-CD) inclusion complex (HP-β-CD/BZL) into nanoliposomes “HP-β-CD/BZL-loaded nanoliposomes” (BCL) | Liposomes Cyclodextrins | In vitro BZL release study Transcorneal permeability study In vivo IOP measurement | BZL showed a moderate sustained release period of 9 h (1–10 h) BCL showed a 9.36-fold increase in the permeability coefficient compared with commercially available BZL BCL formulation reduced IOP in less than 1 h, reached peak efficacy (− 32.3%) at 2 h and showed a sustained effect for 12 h BZL suspension lowered IOP at 30 min and reached its peak efficacy at 1 h. From 2 to 12 h after instillation, BCL resulted in significantly lower IOPs compared with BZL suspension | [149] |
Brinzolamide (BZL)-loaded PLGA nanoparticles | Poly(lactic-co-glycolic acid) (PLGA) nanoparticles | A single subconjunctival injection of BZL-PLGA nanoparticles In vitro drug release studies In vivo IOP measurements (on normotensive albino rabbits) | Two formulations of BZL-loaded PLGA nanoparticles displayed excellent release efficiency values: A19 released about 70% of the drug in 6 months, while B11 released about 90% of the drug in 6 months After subconjunctival administration peak IOP lowering were 78.4 ± 3.4% for A19 BZL nanoparticles; 71.6 ± 2.0% for B11 BZL nanoparticles; and 56.8 ± 6.3% for BZL aqueous suspension | [150] |
Brimonidine
Hypotensive drug/nanosystem | Pharmaceutical form | Study design/model | Results | References |
---|---|---|---|---|
Nanovesicles of BRD | Liposomes and niosomes | In vitro and ex in vitro drug release studies In vivo IOP-lowering activity in albino rabbits Group 1: marketed formulation (BRD 0.02%) Group 2: liposomes Group 3: niosomes | In vitro and ex in vitro drug release profiles of all the nanovesicule formulations showed a more extended drug release compared to the currently available commercial solution Efficacy was greater compared to the commercial product, whose activity was not sustained beyond 60 min | [154] |
Eudragit-based brimonidine tartrate nanoparticle formulations (BRD-loaded ERS– ERL nanoparticles) | Eudragit nanoparticles | In vitro drug release studies In vivo pharmacodynamic studies (employing glaucomatous New Zealand rabbits): IOP-lowering efficacy studies performed by instillation of aqueous dispersion of nanoparticles and conventional eye drop solution | All the selected BRD-loaded ERS–ERL nanoparticles showed an extension of the drug release in vitro Results of in vivo pharmacodynamic efficacy studies of selected BRD-loaded ERS–ERL nanoparticle formulations and marketed BRD eye drops showed a similar peak IOP reduction, but prolonged IOP efficacy (marketed eye drops duration of 6 h compared to 36–72 h with the nanoparticles formulations) | [155] |
BRD-loaded microspheres using poly(lactic acid) (PLA) | Microspheres | In vitro release kinetics of BRD In vivo experimental treatment groups (employing New Zealand rabbits): Single microneedle injection of BRD-loaded microspheres into the supraciliary space BRD (0.15%) commercial eye drops (administered three times a day to the upper conjunctival sac, for a week) | After topical delivery of BRD, a consistent IOP reduction of 2–4 mmHg was detected, but the IOP quickly returned to baseline after the interruption of the drops BRD-loaded microspheres high dose group (30% BRD-loaded microspheres) showed IOP reduction of the treated eye for 33 days, after a single injection into the supraciliary space | [156] |
Optimized BRD-loaded chitosan (CS) and sodium alginate (ALG) nanoparticles | CS and ALG nanoparticles | In vitro studies (drug release and cytotoxicity assays) In vivo studies (mice strains BXD29 and BXD96): a single dose of the test formulations or commercial BRD eye drops (BRD 0.15%) were instilled into the inferior conjunctival sac | In vitro toxicity studies did not show significant differences between nano-based formulations and commercial BRD eye drops All nano-based formulations showed a greater sustained IOP-lowering effect compared to the commercial BRD. Time required for IOP to return to baseline ranged from 17.2 to 25.2 h for nano-based formulations, compared to 7–7.4 h for commercial BRD | [157] |
BRD-loaded nanostructured lipid carriers | Nanostructured (NLC) and solid (SLN) lipid nanoparticles | In vitro drug release study Ex vivo permeability study In vivo studies (a single dose (50 µL) of lipid nanoparticles was instilled into the lower conjunctival sac of a normotensive albino rabbit). Ocular tolerance analysis, IOP measurements, and ocular histology were performed | Both NLCs and SLNs showed a biphasic release pattern. SLNs showed 61.74 ± 2.56% drug released after 2 h and 74.34 ± 0.14% after 6 h, while NLCs showed 66.89 ± 3.4% drug released after 2 h and 95.8 ± 2.31% after 6 h. Commercial BRD showed a unique burst release of 88.76 ± 1.78% within the first hour NLCs demonstrated a permeability coefficient 1.23-fold higher than that of SLNs Peak IOP lowering with NLCs, SLNs, and commercial BRD eye drops was 13.14 ± 1.28, 10.03 ± 0.32, and 7.84 ± 1.04 mmHg, respectively The peak IOP effect occurred after 6 h for NLCs, after 4 h for commercial BRD, and after 2 h for SLNs NLCs and SLNs were found in the anterior chamber of treated eyes, indicating that lipid nanoparticles penetrate through the cornea | [158] |
BRD-loaded microspheres/carrier system (M/CS) | Microspheres poly(d,l-lactic-co-glycolic acid) (PLGA) | In vitro release studies In vivo studies (IOP measurements after BRD-loaded M/CS subconjunctival implantation in normal and glaucomatous eyes) | After a single dose of the BRD-loaded M/CS, an IOP reduction of 20 mmHg was achieved after 1 day, and was sustained over a period of 55 days M/CS structure remained intact for easy removal after BRD was fully released, even as long as 70 days after implantation | [159] |
Prostaglandin Analogues
Hypotensive drug/nanosystem | Pharmaceutical form | Study design/model | Results | References |
---|---|---|---|---|
Latanoprost-loaded liposomes (large unilamellar vesicles) | Liposomes | In vivo human study: a single subconjunctival injection of liposomal latanoprost was administered to one eye of 6 subjects with ocular hypertension or primary open-angle glaucoma | Baseline IOP was 27.55 ± 3.25 mmHg | [163] |
Mean IOP decreased within 1 h to 14.52 ± 3.31 mmHg (range 10–18 mmHg) | ||||
A minimum 20% IOP reduction was observed through 3 months after injection | ||||
No adverse events were reported | ||||
Latanoprost acid (LA)-loaded poly(lactide)/monomethoxy-poly(ethylene glycol) (PLA-PEG) nanoparticles (NPs) | PLA (40) PEG (5) nanoparticles | In vivo studies: subconjunctival injections were administered into the subconjunctival space of three groups of normotensive albino rabbits: (A) LA-loaded NPs (equivalent to 8.5 mg LA); (B) A free LA solution of the same drug content; (C) blank NPs IOP was monitored for 8 consecutive days In vitro studies analyzed drug entrapment efficiency, and release of LA Aqueous humor (AH) levels of LA were also measured 6 days post-administration | IOP was lower in the LA-loaded PLA-PEG NPs group compared to the other 3 study groups (free drug, blank NP, and control group) The drug entrapment efficiency was 18.3% AH levels of LA were initially higher in the free LA group than the nanoparticle group, but they decreased over time In the nanoparticle group, AH levels of LA increased with time, becoming higher on the 6th day than in the free LA group | [164] |
Latanoprost-loaded egg-phosphatidylcholine (EggPC) liposomes | Liposomes | In vivo studies: after a single subconjunctival injection of the latanoprost-loaded formulation, rabbit eyes were clinically monitored and the IOP recorded | Latanoprost-loaded EggPC liposomes were able to provide a sustained IOP lowering and greater effect compared with daily instillations of topical latanoprost for up to 90 days (4.8 ± 1.5 vs 2.5 + 0.9 mmHg; P = 0.001), with no signs of inflammation | [165] |
Latanoprost-loaded thermosensitive chitosan-based hydrogel (as a topical eye drop formulation) | Hydrogel | In vitro drug release and biocompatibility study of the latanoprost-loaded hydrogel (cell viability assays, hemolysis analysis, and ocular irritation test) In vivo release study (aqueous humor levels of the drug) Latanoprost-loaded hydrogel was administered weekly into the lower lid of an experimental glaucoma model (rabbit). IOP was assessed | No difference was found in cell viability between latanoprost-loaded hydrogel group and the controls No cytotoxic effects were detected on rabbit corneal epithelial cells Latanoprost-loaded hydrogel instilled once a week showed a similar IOP-lowering effect of commercial latanoprost instilled once daily | [166] |
Latanoprost-loaded liposomes, thymoquinone-loaded liposomes, and latanoprost/thymoquinone-loaded liposomes | Liposomes | In vitro drug release In vivo studies: glaucomatous white albino rabbits were treated with latanoprost eye drops and diverse liposome formulations for a period of 6 weeks | Latanoprost/thymoquinone-loaded liposomes and latanoprost-loaded liposomes were able to provide a significant IOP lowering that lasted 8 h Effect of the free latanoprost did not persist for more than 24 h | [167] |
Latanoprost-propylamino-β-cyclodextrin (CD) | Cyclodextrins | In vitro stability and phase solubility analyses Ex vivo corneal permeation studies In vivo ocular tolerability evaluation Histology study | Latanoprost-propylamino-β-CD demonstrated a significant improvement in its solubility and stability Clinical evaluations during 14 days showed that ocular irritation was 15.5% with the latanoprost marketed formulation, 9.5% with the latanoprost- propylamino-β-CD formulation, and 7.1% with the vehicle of the formulations Histological evaluation of ocular tissues demonstrated that Xalatan® induced higher inflammatory cell infiltrates than latanoprost- propylamino-β-CD formulation and the vehicle | [168] |
Chitosan bimatoprost (BIM)-loaded inserts | Hydrogel | In vitro drug release studies Biodistribution studies (free and entrapped BIM, radiolabeled with technetium-99m) In vivo studies (glaucoma induced in Wistar rats): Group 1: BIM-loaded inserts were administered once into the conjunctival sac Group 2: marketed BIM drops Group 3: placebo inserts | Biodistribution studies showed that a higher amount of 99mTc-BIM remained in the eye after chitosan insert implantation compared to eye drop instillation BIM-loaded inserts were able to lower IOP for 4 weeks after one application, whereas marketed eye drop could only lower IOP for 1 day | [169] |
A drug-agnostic intraocularly implantable device was used loaded with bimatoprost. The device was called nanofluidic Vitreal System for Therapeutic Administration (nViSTA) | Implantable intraocular device using a nanochannel membrane | The nViSTA implantable device was designed for sustained and controlled drug delivery and based on a nanochannel membrane (which measures from 2.5 to 250 nm), without the need for actuation, pumps, or repeated clinical intervention This device was tested within a 3-dimensional anatomically similar in silico human eye model to obtain information on the intraocular pharmacokinetic profile | Results from in vitro testing demonstrated a burst of approximately 40 µg of bimatoprost during the first 2 days, followed by a sustained release of bimatoprost from the nViSTA over the subsequent 18 days | [170] |
Bimatoprost-loaded nanosponges (NS); travoprost-loaded nanosponges (NS) | Nanosponge One travoprost nanosponge formulation (50-nm), and 3 bimatoprost nanosponge (NS) formulations were tested: (a) 400-nm NS; (b) 700-nm NS with amorphous (A-NS) cross-linkers, and (c) 700-nm NS with amorphous/crystalline (AC-NS) cross-linkers | Ocular hypertensive C57 mice received NS loaded with 2 prostaglandin analogue hypotensive drugs (travoprost or bimatoprost) by a single intravitreal injection IOP was monitored for 7 weeks To evaluate the possibility of retinal deposition and retinal ganglion cell uptake of NS, 50-nm NS loaded with Neuro-DiO was injected intravitreally | Travoprost NS formulation lowered IOP 19–29% for up to 4 days compared to saline injection Outcomes of the 3 bimatoprost NS formulations were: 400 nm NS lowered IOP 24–33% for up to 17 days compared to saline 700 nm A-NS lowered IOP 22–32% for up to 32 days 700 nm AC-NS lowered IOP 18–26% for up to 32 days Confocal microscopy and orthogonal projections suggested internalization of Neuro-DiO by retinal ganglion cells, which means NS may be effective at targeting these cells | [171] |