A novel fixed-combination timolol-netarsudil-latanoprost ophthalmic solution for the treatment of glaucoma and ocular hypertension

Characterization of Forced Degradation Products of Netarsudil: Optimization and Validation of a Stability-Indicating RP-HPLC Method for Simultaneous Quantification of Process-Related Impurities

Objectives

The aim of this study is to examine resolution, identification, and characterization of forced degradation products of netarsudil by liquid chromatography-tandem mass spectrometry by validating a simple and sensitive high-performance liquid chromatography method for the resolution, identification, and quantification of two process-related impurities in netarsudil.

Materials and Methods

Chromatographic separation was accomplished on a ZORBAX Eclipse XDB C18 (250 x 4.6 mm; 5 µ id) column at room temperature as the stationary phase and 257 nm as the detector wavelength with the mobile phase consisting of acetonitrile, methanol, and pH 4.6 phosphate buffer in 45:35:20 (v/v) at 1.0 mL/min flow rate in isocratic elution.

Results

The method reported very sensitive detection limits of 0.008 µg/mL for impurity 1 and 0.003 µg/mL for impurity 1. The method produces a calibration curve linear in the concentration level of 25-200 for netarsudil and 0.025-0.2 µg/mL for impurities. The proposed method gives acceptable results for other validation parameters such as accuracy, precision, ruggedness, and robustness. The drug was subjected to various stress conditions such as acid, base, peroxide, and thermal and ultraviolet light to investigate the stability-indicating ability of the method. Considerable degradation was observed in stress studies, and the degradation products were well resolved from process-related impurities. The characterization of degradation products was performed on the basis of collision-induced dissociation mass spectral data, and the possible structures of the six degradation compounds of netarsudil were proposed.

Conclusion

The outcomes of other validation studies were likewise satisfactory and proven adequate for the regular analysis of netarsudil and its process-related impurities in bulk drug and pharmaceutical dosage forms and can also be applied for the evaluation of the stress degradation mechanism of netarsudil.

Advancing ophthalmic delivery of flurbiprofen via synergistic chiral resolution and ion-pairing strategies

Flurbiprofen (FB), a nonsteroidal anti-inflammatory drug, is widely employed in treating ocular inflammation owing to its remarkable anti-inflammatory effects. However, the racemic nature of its commercially available formulation (Ocufen®) limits the full potential of its therapeutic activity, as the (S)-enantiomer is responsible for the desired anti-inflammatory effects. Additionally, the limited corneal permeability of FB significantly restricts its bioavailability. In this study, we successfully separated the chiral isomers of FB to obtain the highly active (S)-FB. Subsequently, utilizing ion-pairing technology, we coupled (S)-FB with various counter-ions, such as sodium, diethylamine, trimethamine (TMA), and l-arginine, to enhance its ocular bioavailability. A comprehensive evaluation encompassed balanced solubility, octanol-water partition coefficient, corneal permeability, ocular pharmacokinetics, tissue distribution, and in vivo ocular anti-inflammatory activity of each chiral isomer salt. Among the various formulations, S-FBTMA exhibited superior water solubility (about 1-12 mg/ml), lipid solubility (1< lg Pow < 3) and corneal permeability. In comparison to Ocufen®, S-FBTMA demonstrated significantly higher in vivo anti-inflammatory activity and lower ocular irritability (such as conjunctival congestion and tingling). The findings from this research highlight the potential of chiral separation and ion-pair enhanced permeation techniques in providing pharmaceutical enterprises focused on drug development with a valuable avenue for improving therapeutic outcomes.

Connective Tissue Growth Factor: Regulation, Diseases, and Drug Discovery

In drug discovery, selecting targeted molecules is crucial as the target could directly affect drug efficacy and the treatment outcomes. As a member of the CCN family, CTGF (also known as CCN2) is an essential regulator in the progression of various diseases, including fibrosis, cancer, neurological disorders, and eye diseases. Understanding the regulatory mechanisms of CTGF in different diseases may contribute to the discovery of novel drug candidates. Summarizing the CTGF-targeting and -inhibitory drugs is also beneficial for the analysis of the efficacy, applications, and limitations of these drugs in different disease models. Therefore, we reviewed the CTGF structure, the regulatory mechanisms in various diseases, and drug development in order to provide more references for future drug discovery.

Combination of self-assembling system and N,O-carboxymethyl chitosan improves ocular residence of anti-glaucoma drug

Glaucoma is known to be one of the principal causes of vision loss due to elevated intraocular pressure. Currently, latanoprost eye drops is used as first-line treatment for glaucoma; however, it possesses low bioavailability due to rapid precorneal clearance. A novel delivery system with a mucoadhesive property could overcome this problem. Therefore, we attempt to develop a combination of self-assembling latanoprost nanomicelles (Latcel) and a mucoadhesive polymer (N,O-carboxymethyl chitosan: N,O-CMC) to improve the corneal residence time. Latcel was developed using Poloxamer-407 by thin film hydration method, followed by the addition of N,O-CMC using simple solvation to obtain Latcel-CMC and characterized using various physicochemical characterization techniques. The particle size of Latcel-CMC was 94.07 ± 2.48 nm and a zeta potential of -16.03 ± 0.66 mV, with a sustained release for 24h whereas marketed latanoprost drops released 90 % of the drug within 1h. In vitro cytotoxicity studies, HET-CAM, and in vivo Draize test showed the biocompatibility of Latcel-CMC. Cellular uptake studies performed using fluorescein isothiocyanate (FITC) loaded nanomicelles in human corneal epithelial cells indicates the increased cellular uptake as compare to plain FITC solution. In vivo ocular residence time was evaluated in Wistar rats using Indocyanine green (ICG) loaded nanomicelles by an in vivo imaging system (IVIS), indicating Latcel-CMC (8h) has better residence time than plain ICG solution (2h). The Latcel-CMC showed improved corneal residence time and sustained release of latanoprost due to increased mucoadhesion. Thus, the developed N,O-Carboxymethyl chitosan based nanomicelles eye drop could be a better strategy than conventional eye drops for topical delivery of latanoprost to treat glaucoma.

Rho Kinase (ROCK) Inhibitors for the Treatment of Glaucoma

Glaucoma is the most common cause of irreversible blindness worldwide. It is characterized by progressive optic nerve degeneration and loss of visual field. Pathological increased intraocular pressure is its main modifiable risk factor. Rho kinase inhibitors are developed as a new class of glaucoma medication that increases outflow facility from the conventional aqueous humor outflow pathway. Additionally, they also have neuroprotective and anti-scarring effects that can might increase the success rate of glaucoma filtration surgery. This review aims to summarize the current concept of Rho kinase inhibitors in the treatment of glaucoma from beach to bedside.

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.