Tailor-made legumain/pH dual-responsive doxorubicin prodrug-embedded nanoparticles for efficient anticancer drug delivery and in situ monitoring of drug release.

Legumain enzyme is a well-conserved lysosomal cysteine protease and is over-expressed in many tumor cells and tumor stromal cells and exhibits higher protease activity under acidic conditions, such as in lysosomes and endosomes. Legumain enzyme-triggered drug delivery systems have demonstrated potential therapeutic values in cancer targeted therapy. To realize a more efficient delivery of anticancer therapeutic agents, we herein report a legumain/pH dual-responsive drug delivery system for enhancing site-specific controlled release of antitumor drugs. The carrier (named "DS-NA") is a hybrid vector constituting PEG-b-PBLA polymers, pH-responsive OAPI polymers, and legumain-sensitive peptide-doxorubicin prodrug decorated fluorescent carbon dots (CDs-C9-AANL-DOX). In tumor cells, DS-NA could disassemble rapidly in acidic environments, and then release doxorubicin through legumain digestion. Except as a drug vector, the drug release process from DS-NA could also be dynamically monitored by CLSM as the DOX was released from the surface of CDs through the AANL peptide linker digested by legumain, then transferred into the cell nucleus and exerted cytotoxicity, while the CDs themselves remained in the cytoplasm. As a control, the CDs-C9-DOX, which did not contain the AANL peptide linker, also still resided in the cytoplasm. Furthermore, in vivo studies show that DS-NA had a stronger inhibitory effect on tumor tissue with attenuated side effects to normal tissues than control nanoparticles or free drugs, which may be due to comprehensive effects including pH/legumain dual-triggered drug release, long blood circulation periods, and EPR effects. Together, a combination strategy of acid sensitivity and legumain enzyme sensitivity used for site-specific controlled release of drugs provides a novel method for enhanced and precise antitumor chemotherapy.

Programmed co-delivery of platinum nanodrugs and gemcitabine by a clustered nanocarrier for precision chemotherapy for NSCLC tumors.

Recently, ultra-small platinum nanoparticles (USPtNs) have been found that can kill cancer cells by leaching Pt ions into acidic organelles, such as cell endosomes or lysosomes. Unfortunately, tumor-specific accumulation is difficult to achieve with such platinum nanodrugs of less than 5 nm due to their short half-life in vivo and broad range of toxicity to normal tissues. Programmable multi-drug release for combinational chemotherapy by hierarchical nanostructures provides a promising solution for cancer-targeted therapy. Herein, we demonstrated a pH/redox dual stimuli-responsive clustered nanoparticle as a vehicle for simultaneously delivering USPtNs and gemcitabine (GEM) to treat non-small-cell lung cancer. The clustered nanoparticle (denoted as GP-NA) was composed of disulfide-bond-containing GEM-grafted copolymers (PEG-b-P(LL-g-GEM)), pH-sensitive polypeptides (OAPI), and USPtNs. Such a hybrid nanosystem completes multiple tasks inside cancer cells, which include the generation of cytotoxic Pt ions in response to lysosomal acidic environments and the subsequent release of GEM in cytoplasmic reduction environments. Compared with non-acid-sensitive nanoparticles or free drugs, GP-NA exhibited cumulative and enhanced anti-tumor efficacy in vivo, which may be attributed to the simultaneous inhibition of ribonucleotide reductase and DNA replication in nuclei by the GEM and Pt ions. Together, our work provides a promising strategy in the co-delivery of USPtNs and GEM for precision cancer chemotherapy.

Sequentially Site-Specific Delivery of Thrombolytics and Neuroprotectant for Enhanced Treatment of Ischemic Stroke.

Ischemic stroke caused by a thrombus clog and ischemia is one of the most lethal and disabling cerebrovascular diseases. A sequentially targeted delivery system is highly desired to deliver thrombolytics and neuroprotectant to the site of the thrombus and ischemic penumbra, respectively, to pursue a maximized combinational effect. Inspired by the vital roles that platelets play in thrombus formation, herein, we develop a bioengineered "nanoplatelet" (tP-NP-rtPA/ZL006e) for sequentially site-specific delivery of recombinant tissue plasminogen activator (rtPA) and neuroprotectant (ZL006e) for ischemic stroke treatment. The tP-NP-rtPA/ZL006e consists of a ZL006e-loaded dextran derivative polymeric nanoparticle core and platelet membrane shell conjugated with thrombin-cleavable Tat-peptide-coupled rtPA. Mediated by the cloak of the platelet membrane, tP-NP-rtPA/ZL006e targets the thrombus site and rtPA is triggered to release by the upregulated thrombin. Subsequently, the in situ exposed Tat peptide enhanced penetration of the "nanoplatelet" across the blood-brain barrier into ischemic brain for ZL006e site-specific delivery. From the in vitro and in vivo evaluation, tP-NP-rtPA/ZL006e is demonstrated to significantly enhance the anti-ischemic stroke efficacy in the rat model  with middle cerebral artery occlusion, showing a 63 and 72% decrease in ischemic area and reactive oxygen species level compared to that with free drug combination, respectively.

Bioengineered Boronic Ester Modified Dextran Polymer Nanoparticles as Reactive Oxygen Species Responsive Nanocarrier for Ischemic Stroke Treatment.

Ischemic stroke is a leading cause of long-term disability and death worldwide. Current drug delivery vehicles for the treatment of ischemic stroke are less than satisfactory, in large part due to their short circulation lives, lack of specific targeting to the ischemic site, and poor controllability of drug release. In light of the upregulation of reactive oxygen species (ROS) in the ischemic neuron, we herein developed a bioengineered ROS-responsive nanocarrier for stroke-specific delivery of a neuroprotective agent, NR2B9C, against ischemic brain damage. The nanocarrier is composed of a dextran polymer core modified with ROS-responsive boronic ester and a red blood cell (RBC) membrane shell with stroke homing peptide (SHp) inserted. These targeted "core-shell" nanoparticles (designated as SHp-RBC-NP) could thus have controlled release of NR2B9C triggered by high intracellular ROS in ischemic neurons after homing to ischemic brain tissues. The potential of the SHp-RBC-NP for ischemic stroke therapy was systematically evaluated in vitro and in rat models of middle cerebral artery occlusion (MCAO). In vitro results showed that the SHp-RBC-NP had great protective effects on glutamate-induced cytotoxicity in PC-12 cells. In vivo pharmacokinetic (PK) and pharmacodynamic (PD) testing further demonstrated that the bioengineered nanoparticles can drastically prolong the systemic circulation of NR2B9C, enhance the active targeting of the ischemic area in the MCAO rats, and reduce ischemic brain damage.

Stimuli-responsive delivery vehicles based on mesoporous silica nanoparticles: recent advances and challenges.

In the past decade, stimuli-responsive drug delivery vehicles based on surface-functionalized mesoporous silica nanoparticles (MSNs) have attracted intense interest as a new type of drug carrier. These intelligent drug delivery systems have been demonstrated to enable precise drug release into highly specified targets and exhibit nearly "zero premature release" in systemic circulation. It is expected that an in-depth understanding of the basic mechanisms of the MSN-based stimuli-responsive drug delivery systems (DDSs) would further contribute to this breakthrough field of nanomedicine. In this review, the recent advances in the development of stimuli-responsive systems based on MSNs are summarized and discussed, including single stimuli-responsive DDSs, dual stimuli-responsive DDSs and multi stimuli-responsive DDSs. The challenges for stimuli-responsive DDSs based on MSNs with regards to future translation into clinical use are also simply discussed.

Enhanced Antiglioma Efficacy of Ultrahigh Loading Capacity Paclitaxel Prodrug Conjugate Self-Assembled Targeted Nanoparticles.

Glioblastoma multiforme (GBM) presents one of the most lethal brain tumor with a dismal prognosis. And nanodrug delivery system (nano-DDS) have raised a lot of concern, while the conventional nanoformulations addressed many limitations, especially the low drug loading capacity and poor stability in vivo. Herein, we proposed PTX prodrug (PTX-SS-C18) conjugate self-assembled nanoparticles (PSNPs) functionalized with Pep-1, glioma homing peptide, to overcome the blood brain tumor barrier (BBTB) via interleukin 13 receptor α2 (IL-13Rα2)-mediated endocytosis for targeting GMB. This nanocarrier was with ultrahigh drug loading capacity (56.03%) and redox-sensitivity to the up-expression of glutathione in glioma tumors. And compared with PEG-PSNPs, Pep-PSNPs could significantly enhance cellular uptake in U87MG cells via IL-13Rα2-mediated endocytosis. Enhanced cytotoxicity of Pep-PSNPs against U87MG cells and BCEC cells pretreated with glutathione monoester (GSH-OEt) confirmed that this nanosystem was sensitive to reduction environment, and there was significant difference between targeting and nontargeting groups in MTT assay. Real-time fluorescence image of intracranialU87MG glioma-bearing mice revealed that Pep-PSNPs could more efficiently accumulate at tumor site and improve the penetration. Furthermore, the ex vivo fluorescence imaging and corresponding semiquantitative results displayed that the glioma fluorescence intensity of Pep-PSNPs group was 1.74-fold higher than that of nontargeting group. Pep-PSNPs exhibited remarkable antiglioblastoma efficacy with an extended median survival time. In conclusion, Pep-PSNPs had a promising perspective as a targeting drug delivery system of PTX for glioma treatment.

Enhanced Antiglioblastoma Efficacy of Neovasculature and Glioma Cells Dual Targeted Nanoparticles.

Combining treatment of anticancer cells and antiangiogenesis is considered to be a potential targeted strategy for brain glioblastoma therapy. In this study, by utilizing the overexpression of Interleukin 13 receptor α2 (IL-13Rα2) on the glioma cells and heparan sulfate on neovascular endothelial cells, we developed a paclitaxel (PTX) loaded Pep-1 and CGKRK peptide-modified PEG-PLGA nanoparticle (PC-NP-PTX) for glioma cells and neovasculature dual-targeted chemotherapy to enhance the antiglioma efficacy. There were significant differences both on the enhancement of cellular uptake in HUVEC and C6 cells and on the improvement of in vitro antiglioma activity in the respect of proliferation, tumor spheroid growth, tube formation, and migration between PC-NP-PTX and Taxol and NP-PTX. As for C6 cells, the IC50 were 3.59 ± 0.056, 2.37 ± 0.044, 1.38 ± 0.028, 1.82 ± 0.035, and 1.00 ± 0.016 µg/mL of Taxol, NP-PTX, Pep-NP-PTX, CGKRK-NP-PTX, and PC-NP-PTX, and for HUVEC cells, the IC50 were 0.44 ± 0.006, 0.33 ± 0.005, 0.25 ± 0.005, 0.19 ± 0.004, and 0.16 ± 0.004 µg/mL of Taxol, NP-PTX, Pep-NP-PTX, CGKRK-NP-PTX, and PC-NP-PTX, respectively. In vivo distribution assays confirmed that PC-NP-PTX targeted and accumulated effectively at glioma site. PC-NP-PTX showed a longer median survival time of 61 days when compared with Taxol (22 days), NP-PTX (24 days), Pep-NP-PTX (32 days), and CGKRK-NP-PTX (34 days). The in vivo antiglioma efficacy and safety evaluation showed PC-NP-PTX significantly enhanced the antiglioma efficacy and displayed negligible acute toxicity.

PEGylated Polyamidoamine dendrimer conjugated with tumor homing peptide as a potential targeted delivery system for glioma.

Glioblastoma multiforme (GBM) is the most common and aggressive primary central nervous system (CNS) tumor with a short survival time. The failure of chemotherapy is ascribed to the low transport of chemotherapeutics across the Blood Brain Tumor Barrier (BBTB) and poor penetration into tumor tissue. In order to overcome the two barriers, small nanoparticles with active targeted capability are urgently needed for GBM drug delivery. In this study, we proposed PEGylated Polyamidoamine (PAMAM) dendrimer nanoparticles conjugated with glioma homing peptides (Pep-1) as potential glioma targeting delivery system (Pep-PEG-PAMAM), where PEGylated PAMAM dendrimer nanoparticle was utilized as carrier due to its small size and perfect penetration into tumor and Pep-1 was used to overcome BBTB via interleukin 13 receptor α2 (IL-13Rα2) mediated endocytosis. The preliminary availability and safety of Pep-PEG-PAMAM as a nanocarrier for glioma was evaluated. In vitro results indicated that a significantly higher amount of Pep-PEG-PAMAM was endocytosed by U87 MG cells. In vivo fluorescence imaging of U87MG tumor-bearing mice confirmed that the fluorescence intensity at glioma site of targeted group was 2.02 folds higher than that of untargeted group (**p<0.01), and glioma distribution experiment further revealed that Pep-PEG-PAMAM exhibited a significantly enhanced accumulation and improved penetration at tumor site. In conclusion, Pep-1 modified PAMAM was a promising nanocarrier for targeted delivery of brain glioma.

Dual targeted nanocarrier for brain ischemic stroke treatment.

Focal cerebral ischemia, known as stroke, causes serious long-term disabilities globally. Effective therapy for cerebral ischemia demands a carrier that can penetrate the blood-brain barrier (BBB) and subsequently target the ischemia area in brain. Here, we designed a novel neuroprotectant (ZL006) loaded dual targeted nanocarrier based on liposome (T7&SHp-P-LPs/ZL006) conjugated with T7 peptide (T7) and stroke homing peptide (SHp) for penetrating BBB and targeting ischemia area, respectively. Compared with non-targeting liposomes, T7&SHp-P-LPs/ZL006 could transport across BCEC cells and significantly enhance cellular uptake and reduce cells apoptosis of excitatory amino acid stimulated PC-12 cells. However, there was no significant difference in cellular uptake between SHp-modified and plain liposomes when PC-12 cells were incubated without excitatory amino acid. Besides, ex vivo fluorescent images indicated that DiR labeled T7&SHp-P-LPs could efficiently transport across BBB and mostly accumulated in ischemic region rather than normal cerebral hemisphere of MCAO rats. Furthermore, T7&SHp-P-LPs/ZL006 could enhance the ability of in vivo anti-ischemic stroke of MCAO rats. These results demonstrated that T7&SHp-P-LPs could be used as a safe and effective dual targeted nanocarrier for ischemic stroke treatment.

Improved anti-glioblastoma efficacy by IL-13Rα2 mediated copolymer nanoparticles loaded with paclitaxel.

Glioma presents one of the most malignant brain tumors, and the therapeutic effect is often limited due to the existence of brain tumor barrier. Based on interleukin-13 receptor α2 (IL-13Rα2) over-expression on glioma cell, it was demonstrated to be a potential receptor for glioma targeting. In this study, Pep-1-conjugated PEGylated nanoparticles loaded with paclitaxel (Pep-NP-PTX) were developed as a targeting drug delivery system for glioma treatment. The Pep-NP-PTX presented satisfactory size of 95.78 nm with narrow size distribution. Compared with NP-PTX, Pep-NP-PTX exhibited significantly enhanced cellular uptake in C6 cells (p < 0.001). The in vitro anti-proliferation evaluation showed that the IC50 were 146 ng/ml and 349 ng/ml of Pep-NP-PTX and NP-PTX, respectively. The in vivo fluorescent image results indicated that Pep-NP had higher specificity and efficiency in intracranial tumor accumulation. Following intravenous administration, Pep-NP-PTX could enhance the distribution of PTX in vivo glioma section, 1.98, 1.91 and 1.53-fold over that of NP-PTX group after 0.5, 1 and 4 h, respectively. Pep-NP-PTX could improve the anti-glioma efficacy with a median survival time of 32 days, which was significantly longer than that of PTX-NP (23 days) and Taxol(®) (22 days). In conclusion, Pep-NP-PTX is a potential targeting drug delivery system for glioma treatment.

Enhanced anti-ischemic stroke of ZL006 by T7-conjugated PEGylated liposomes drug delivery system.

The treatment for ischemic stroke is one of the most challenging problems and the therapeutic effect remains unsatisfied due to the poor permeation of drugs across the blood brain barrier (BBB). In this study, HAIYPRH (T7), a peptide that targeted to transferrin receptor (TfR) can mediate the transport of nanocarriers across the BBB, was conjugated to liposomes for ischemic stroke targeting treatment of a novel neuroprotectant (ZL006). T7-conjugated PEGylated liposomes (T7-P-LPs) loaded with ZL006 (T7-P-LPs/ZL006) were showed satisfactory vesicle size and size distribution. Furthermore, the cellular uptake results showed that T7 modification increased liposomes uptake by the brain capillary endothelial cells (BCECs) and little cytotoxicity of liposomes with or without ZL006 was observed. The in vivo biodistribution and near-infrared fluorescence imaging evidenced that T7 modification rendered liposomes significantly enhanced the transport of liposomes across the BBB. The pharmacodynamic study suggested that, T7-P-LPs/ZL006 exhibited reduced infarct volume and ameliorated neurological deficit compared with unmodified liposomes or free ZL006. T7-P-LPs/ZL006 could be targeted to brain and displayed remarkable neuroprotective effects. They could be used as a potential targeted drug delivery system of ischemic stroke treatment.

Methazolamide-loaded solid lipid nanoparticles modified with low-molecular weight chitosan for the treatment of glaucoma: vitro and vivo study.

The aims of this study were to design and characterize methazolamide (MTZ)-loaded solid lipid nanoparticles (SLN) with and without modification of low molecular weight chitosan (CS) and compare their potentials for ocular drug delivery. Low molecular weight CS was obtained via a modified chemical oxidative degradation method. SLN with CS (CS-SLN-MTZ) and without CS (SLN-MTZ) were prepared according to a modified emulsion-solvent evaporation method. SLN-MTZ and CS-SLN-MTZ were 199.4 ± 2.8 nm and 252.8 ± 4.0 nm in particle size, -21.3 ± 1.9 mV and +31.3 ± 1.7 mV in zeta potential, respectively. Physical stability studies demonstrated that CS-SLN-MTZ remained stable for at least 4 months at 4 °C, while SLN-MTZ no more than 2 months. A prolonged in vitro release profile of MTZ from CS-SLN-MTZ was obtained compared with SLN-MTZ. Furthermore, CS-SLN-MTZ presented a better permeation property in excised rabbit cornea. In vivo studies indicated that the intraocular pressure lowering effect of CS-SLN-MTZ (245.75 ± 18.31 mmHg × h) was significantly better than both SLN-MTZ (126.74 ± 17.73 mmHg × h) and commercial product Brinzolamide Eye Drops AZOPT® (171.17 ± 16.45 mmHg × h). The maximum percentage decrease in IOP of CS-SLN-MTZ (42.78 ± 7.71%) was higher than SLN-MTZ (27.82 ± 4.15%) and was comparable to AZOPT (38.06 ± 1.25%). CS-SLN-MTZ showed no sign of ocular irritancy according to the Draize method and the histological examination.

Stability of an anti-stroke peptide: driving forces and kinetics in chemical degradation.

NR2B9c (Lys-Leu-Ser-Ser-Ile-Glu-Ser-Asp-Val) is a 9-amino acid peptide that has been illustrated to be a potential anti-stroke drug. For more effective treatment, suitable drug delivery systems should be developed. However, little is known about the stability of NR2B9c which is essential to its formulation. In this study, a reversed-phase high-performance liquid chromatography (HPLC) was applied to study the forced degradation behavior and stability of NR2B9c. HPLC studies were performed with an C8 column using a mobile phase consisting of acetonitrile (14.5:85.5, v/v) and aqueous solution (0.1% trifluoroacetic acid (TFA) and 0.05 M KH2PO4). The flow rate and the wavelength set during HPLC detection were 1.0 mL/min and 205 nm, respectively. The degradation pattern of NR2B9c aqueous solution followed pseudo first-order kinetics. The degradation rate at pH 7.5 was the slowest according to the plotting V-shaped pH-rate profile. The influence of temperature on the rate of reactions was interpreted in terms of Arrhenius equation (r(2)>0.98). Thermodynamic parameters were calculated based on Eyring equation (r(2)>0.98). The concentrations of drug, buffer species, buffer concentrations, oxidation and organic solvents have noticeable effects on the degradation of NR2B9c while ultrasound shows little impact under the experimental conditions. In a word, this study may give a detailed description of stability of NR2B9c.

Nanoparticles functionalized with Pep-1 as potential glioma targeting delivery system via interleukin 13 receptor α2-mediated endocytosis.

The treatment for glioma is one of the most challenging problems and therapeutic effect of glioma is often limited due to poor penetration into the tumor tissue. Interleukin 13 receptor α2 (IL-13Rα2) is over-expressed on tumor including established glioma cell lines and primary glioblastoma cell cultures. However, it will not cause activation of its signaling pathways. So it could be served as a promising targeted moiety for anti-glioma drug delivery. Pep-1, one specific ligand of IL-13Rα2, was identified to exhibit excellent capacity of crossing the blood tumor barrier (BTB) and homing to giloma. In this study, based on the IL-13Rα2-mediated endocytosis, Pep-1 was exploited as a potential ligand for effective glioma-targeting delivery. Pep-1 was functionalized to the surface of PEG-PLGA nanoparticles (Pep-NP) to evaluate its glioma homing, by taking advantage of the excessive expression of the IL-13Rα2 on the surface of glioma cells. Compared with non-targeting nanoparticles, Pep-NP exhibited a significantly enhanced cellular association in rat C6 glioma cells and improved penetration in 3D avascular C6 glioma spheroids. Following intravenous administration, Pep-NP could facilitate the distribution of the coumarin-6 in vivo glioma region, 2.21 times higher than that of NP for quantitative analysis. In conclusion, the Pep-NP could precisely target to the brain glioma, which was a potential targeting drug delivery system for glioma treatment.

Optimization of methazolamide-loaded solid lipid nanoparticles for ophthalmic delivery using Box-Behnken design.

The purpose of the present study was to optimize methazolamide (MTZ)-loaded solid lipid nanoparticles (SLNs) which were used as topical eye drops by evaluating the relationship between design factors and experimental data. A three factor, three-level Box-Behnken design (BBD) was used for the optimization procedure, choosing the amount of GMS, the amount of phospholipid, the concentration of surfactant as the independent variables. The chosen dependent variables were entrapment efficiency, dosage loading, and particle size. The generated polynomial equations and response surface plots were used to relate the dependent and independent variables. The optimal nanoparticles were formulated with 100 mg GMS, 150 mg phospholipid, and 1% Tween80 and PEG 400 (1:1, w/v). A new formulation was prepared according to these levels. The observed responses were close to the predicted values of the optimized formulation. The particle size was 197.8 ± 4.9 nm. The polydispersity index of particle size was 0.239 ± 0.01 and the zeta potential was 32.7 ± 2.6 mV. The entrapment efficiency and dosage loading were about 68.39% and 2.49%, respectively. Fourier transform infrared spectroscopy (FT-IR) study indicated that the drug was entrapped in nanoparticles. The optimized formulation showed a sustained release followed the Peppas model. MTZ-SLNs showed significant prolonged decreasing intraocular pressure effect comparing with MTZ solution in vivo pharmacodynamics studies. The results of acute eye irritation study indicated that MTZ-SLNs and AZOPT both had no eye irritation. Furthermore, the MTZ-SLNs were suitable to be stored at low temperature (4 °C).

Formulation and characterization of hydrophilic drug diclofenac sodium-loaded solid lipid nanoparticles based on phospholipid complexes technology.

To successfully prepare the diclofenac sodium (DS)-loaded solid lipid nanoparticles (SLNs), phospholipid complexes (PCs) technology was applied here to improve the liposolubility of DS. Solid lipid nanoparticles (SLNs) loaded with phospholipid complexes (PCs) were prepared by the modified emulsion/solvent evaporation method. DS could be solubilized effectively in the organic solvents with the existence of phospholipid and apparent partition coefficient of DS in PCs increased significantly. X-ray diffraction analysis suggested that DS in PCs was either molecularly dispersed or in an amorphous form. However, no significant difference was observed between the Fourier transform infrared spectroscopy (FT-IR) spectra of physical mixture and that of PCs. Particles with small sizes, narrow polydispersity indexes and high entrapment efficiencies could be obtained with the addition of PCs. Furthermore, according to the transmission electron microscopy, a core-shell structure was likely to be formed. The presence of PCs caused the change of zeta potential and retarded the drug release of SLNs, which indicated that phospholipid formed multilayers around the solid lipid core of SLNs. Both FT-IR and differential scanning calorimetry analysis also illustrated that some weak interactions between DS and lipid materials might take place during the preparation of SLNs. In conclusion, the model hydrophilic drug-DS can be formulated into the SLNs with the help of PCs.

A potential carrier based on liquid crystal nanoparticles for ophthalmic delivery of pilocarpine nitrate.

Poor corneal penetration and short preocular retention of a clinical hydrophilic drug, pilocarpine nitrate (PN), for the treatment of open-angle glaucoma and acute angle-closure glaucoma, limit its ocular application. The purpose of this study was to investigate the potential of liquid crystal nanoparticles (LCNPs) for ocular delivery of PN. LCNPs were developed by a top-down method using glyceryl monoolein (GMO) and water in the presence of stabilizer Poloxamer 407. They were characterized by transmission electron microscopy (TEM) and small angle X-ray diffraction (SAXS). The size of LCNP is 202.28±19.32 nm and the encapsulation efficiency reached 61.03%. The in vitro release profiles indicated that PN could keep sustained release from PN-loaded LCNPs for 8h. An ex vivo corneal permeation study revealed that the apparent permeability coefficient of PN-loaded LCNPs was 2.05-fold higher than that of commercial eye drops. In addition, the topical administration test showed that PN-loaded LCNPs had a prolonged effect on decreasing intraocular pressure (IOP) of rabbits compared with commercial drug and physiological saline. In conclusion, LCNPs had been demonstrated to be potential for controlled-release ocular drug delivery.

Ophthalmic delivery of brinzolamide by liquid crystalline nanoparticles: in vitro and in vivo evaluation.

Brinzolamide (BLZ) is a drug used to treat glaucoma; however, its use is restricted due to some unwanted adverse events. The goal of this study was to develop BLZ-loaded liquid crystalline nanoparticles (BLZ LCNPs) and to figure out the possibility of LCNPs as a new therapeutic system for glaucoma. BLZ LCNPs were produced by a modified emulsification method and their physicochemical aspects were estimated. In vitro release study revealed BLZ LCNPs displayed to some extent prolonged drug release behavior in contrast to that of BLZ commercial product (Azopt®). The ex vivo apparent permeability coefficient of BLZ LCNP systems demonstrated a 3.47-fold increase compared with that of Azopt®. The pharmacodynamics was checked over by calculating the percentage fall in intraocular pressure and the pharmacodynamic test showed that BLZ LCNPs had better therapeutic potential than Azopt®. Furthermore, the in vivo ophthalmic irritation was evaluated by Draize test. In conclusion, BLZ LCNPs would be a promising delivery system used for the treatment of glaucoma, with advantages such as lower doses but maintaining the effectiveness, better ocular bioavailability, and patient compliance compared with Azopt®.

Preformulation study of methazolamide for topical ophthalmic delivery: physicochemical properties and degradation kinetics in aqueous solutions.

Methazolamide (MTZ) is an anti-glaucoma drug. The present paper aims to characterize the physicochemical properties and degradation kinetics of MTZ to provide a basis for topical ophthalmic delivery. With the increase in pH (pH 5.5-8.0) of aqueous solution, the solubility of the compound increased while the partition coefficient (Ko/w) which was estimated in the system n-octanol/aqueous solution decreased. The degradation of MTZ in aqueous solution followed pseudo-first-order kinetic. The degradation rate kpH is the rate in the absence of buffer catalysis. Plotting the natural logarithm of kpH versus the corresponding pH value gave a V-shaped pH-rate profile with a maximum stability at pH 5.0. The degradation rate constants as a function of the temperature obeyed the Arrhenius equation (R(2)=0.9995 at pH 7.0 and R(2)=0.9955 at pH 9.0, respectively). A decrease in ionic strength and buffer concentration displayed a stabilizing effect on MTZ. Buffer species also influenced the MTZ hydrolysis. Phosphate buffer system was more catalytic than tris and borate buffer systems. In brief, it is important to consider the physicochemical properties and the stability of MTZ during formulation.

A potential new therapeutic system for glaucoma: solid lipid nanoparticles containing methazolamide.

Methazolamide (MTA) is an antiglaucoma drug; however, there are many side effects of its systemic administration with insufficient ocular therapeutic concentrations. The aim of this study was to formulate MTA-loaded solid lipid nanoparticles (SLNs) and evaluate the potential of SLNs as a new therapeutic system for glaucoma. SLNs were prepared by a modified emulsion-solvent evaporation method and their physicochemical characteristics were evaluated. The pharmacodynamics was investigated by determining the percentage decrease in intraocular pressure. The ocular irritation was studied by Draize test. Despite a burst release of SLNs, the pharmacodynamic experiment indicated that MTA-SLNs had higher therapeutic efficacy, later occurrence of maximum action, and more prolonged effect than drug solution and commercial product. Formulation of MTA-SLNs would be a potential delivery carrier for ocular delivery, with the advantages of a more intensive treatment for glaucoma, lower in doses and better patient compliance compared to the conventional eye drops.