Development and evaluation of extended release ciprofloxacin HCl ocular inserts employing natural and synthetic film forming agents

Pullulan as a sustained release carrier for ocular drug delivery: a review

Pullulan, an exopolysaccharide, obtained from the fungus Aureobasidium pullulans, is a non-ionic, hydrophilic, biodegradable, biocompatible, and tolerogenic polymers that is used for the formulation of bioconjugates in the therapeutic delivery to target different cells and tissues. It is known to possess outstanding film-casting qualities and can produce a clear and biodegradable film. Furthermore, appropriate derivatizing pullulan provides active surfaces that facilitate binding with active pharmaceutical ingredients to the polymer backbone to produce micro/nanoparticulate systems for controlled or sustained drug release. Ophthalmic problems like glaucoma, age-related macular degeneration, and cataracts are very prevalent across the globe, and their treatment options mainly include conventional topical solutions and gels, which possess very low drug-contact time and poor bioavailability, leading to frequent dosing and patient incompliance. Sustained release dosage forms like ocuserts, ocular films, and in-situ gels can help in achieving the intended therapeutic outcomes for an extended duration by minimizing the number of doses. Here, we present a comprehensive critical review of the utilization and application of pullulan, together with its derivatives, to combat problems with ocular medication administration. This article also provides insight for further research on this topic to utilize its advantages to the fullest in the future for improved delivery of therapeutics in the treatment of ocular disorders.

Extended release of ciprofloxacin from commercial silicone-hydrogel and conventional hydrogel contact lenses containing vitamin E diffusion barriers

SIGNIFICANCE

Vitamin E could be used as a coating with commercial silicone hydrogel lenses to extend the release of various ophthalmic drugs. This concept could provide a promising approach to improve overall ocular therapeutic outcomes for topical ocular drugs.

PURPOSE

This study aimed to develop a contact lens-based ocular drug delivery system using vitamin E as a diffusion barrier to extend the release duration of ciprofloxacin.

METHODS

Five commercial lenses were soaked for 24 hours in various concentrations of vitamin E dissolved in ethanol (0.0125 to 0.2 g/mL). The lenses were loaded with ciprofloxacin for 24 hours in 3 mL of 3 mg/mL of ciprofloxacin/acetic acid solution. The drug release was evaluated in 3 mL of phosphate-buffered saline solution. At t = 0.5, 1, 2, 4, 6, 8, 12, 16, and 24 hours, the amount of ciprofloxacin released was measured using a UV-VIS spectrophotometer at 270 nm.

RESULTS

There was a decrease in ciprofloxacin loading with increasing amounts of vitamin E loaded into the silicone hydrogel lenses. For each lens type, there was an optimal amount of vitamin E loaded that extended the release duration of the drug from 1 hour (without vitamin E) to as long as 16 hours. In contrast, vitamin E loaded into hydrogel lenses had no effect on the amounts of drugs loaded or the release duration.

CONCLUSIONS

Vitamin E can be used as a diffusion barrier with commercially available silicone hydrogel lenses to provide sustained release of ciprofloxacin. The results suggest that vitamin E may form blockages in channels within a silicone hydrogel lens material, thereby forcing a longer path for drugs to diffuse into and out of the lens material. There is an optimal amount of vitamin E that needs to be loaded to extend the release duration, and this is lens material dependent.

Development and optimization of vildagliptin solid lipid nanoparticles loaded ocuserts for controlled ocular delivery: A promising approach towards treating diabetic retinopathy

Diabetes mellitus (DM) is the most prevalent cause of diabetic retinopathy (DRP). DRP has been recognized for a long time as a microvascular disease. Many drugs were used to treat DRP, including vildagliptin (VLD). In addition to its hypoglycemic effect, VLD minimizes ocular inflammation and improves retinal blood flow for individuals with type 2 diabetes mellitus. Nevertheless, VLD can cause upper respiratory tract infections, diarrhea, nausea, hypoglycemia, and poor tolerability when taken orally regularly due to its high water solubility and permeability. Effective ocular administration of VLD is achieved using solid lipid nanoparticles (SLNPs), which improve corneal absorption, prolonged retention, and extended drug release. Ocuserts (OCUs) are sterile, long-acting ocular dosage forms that diminish the need for frequent dosing while improving residence time and stability. Therefore, this study intends to develop VLD solid lipid nanoparticle OCUs (VLD-SLNPs-OCUs) to circumvent the issues commonly associated with VLD. SLNPs were prepared using the double-emulsion/melt dispersion technique. The optimal formula has been implemented in OCUs. Optimization and development of VLD-SLNPs-OCUs were performed using a Box-Behnken Design (BBD). VLD-SLNPs-OCUs loading efficiency was 95.28 ± 2.87%, and differential scanning calorimetry data (DSC) showed the full transformation of VLD to an amorphous state and the excellent distribution in the prepared OCUs matrices. The in vivo release of VLD from the optimized OCUs after 24 h was 35.12 ± 2.47%, consistent with in vitro drug release data of 36.89 ± 3.11. The optimized OCUs are safe to use in the eye, as shown by the ocular irritation test. VLD-SLNPs-OCUs provide extended VLD release, an advantageous alternative to conventional oral dose forms, resulting in fewer systemic adverse effects and less variation in plasma drug levels. VLD-SLNPs-OCUs might benefit retinal microvascular blood flow beyond blood glucose control and may be considered a promising approach to treating diabetic retinopathy.

Active coating of immediate-release evogliptin tartrate to prepare fixed dose combination tablet with sustained-release metformin HCl

This study was aimed to develop a fixed dose combination (FDC) tablet containing a low dose of evogliptin tartrate (6.87 mg) for immediate release combined with a high dose (1000 mg) of sustained-release (SR) metformin HCl appropriate for once daily dosing the treatment of type 2 diabetes. To prepare the FDC tablets, an active coating was used in this study, whereby evogliptin tartrate film was layered on a matrix core tablet containing metformin HCl. To overcome the problem caused by a low-dose drug in combination with a relatively large matrix tablet containing high-dose drug, it was also aimed to confirm the formulation and coating operation for satisfactory content uniformity, and to describe the chemical stability during storage of the amorphous active coating layer formulation in relation to molecular mobility. Furthermore, the in vitro release and in vivo pharmacokinetic profiles of metformin HCl and evogliptin tartrate in the FDC active coating tablet were compared to those of the commercially marketed reference drugs, Diabex XR® (Daewoong, Seoul, Korea) containing metformin HCl and Suganon® (Donga ST, Seoul, Korea) containing evogliptin tartrate. In conclusion, the newly developed FDC active coating tablet in this study was confirmed to be bioequivalent to the reference marketed products in beagle dogs, with satisfactory content uniformity and stability.

Release kinetics of hydroxypropyl methylcellulose governing drug release and hydrodynamic changes of matrix tablet

BACKGROUND

Hydrophilic hydroxypropyl methylcellulose (HPMC) matrix tablets are the standard role model of the oral controlled-release formulation. Nevertheless, the HPMC kinetics for the mechanistic understanding of drug release and hydrodynamic behaviors are rarely investigated. This study aims to investigate the release behaviors of both HPMC and paracetamol (model drug) from the hydrophilic matrix tablet.

METHODS

Two different viscosity grades of HPMC were used (Low viscosity: 6 cps, High viscosity: 4,000 cps). Three different ratios of drug/HPMC (H:38.08%, M:22.85%, and L:15.23% (w/w) of HPMC amounts in total weight) matrix tablets were prepared by wet granulation technique. The release profiles of the drug and HPMC in a matrix tablet were quantitatively analyzed by HPLC and 1H-nuclear magnetic resonance (NMR) spectroscopy. The hydrodynamic changes of HPMC were determined by the gravimetric behaviors such as swelling and erosion rates, gel layer thickness, front movement data,and distributive near-infrared (NIR) chemical imaging of HPMC in a matrix tablet during the dissolution process.

RESULTS

High viscosity HPMC tablets showed slower release of HPMC than the release rate of drug, suggesting that drug release preceded polymer release.Different hydration phenomenon was qualitatively identified and corresponded to the release profiles. The release behaviors of HPMC and drug in the tablet could be distinguished with the significant difference with fitted dissolution kinetics model (Low viscosity HPMC 6cps; Korsmeyer-Peppas model, High viscosity HPMC 4000cps; Hopfenberg model, Paracetamol; Weibull model) according to the weight of ingredients and types of HPMC.

CONCLUSION

The determination of HPMC polymer release correlating with drug release, hydrodynamic behavior, and NIR chemical imaging of HPMC can provide new insights into the drug release-modulating mechanism in the hydrophilic matrix system.

Current Status of Supersaturable Self-Emulsifying Drug Delivery Systems

Self-emulsifying drug delivery systems (SEDDSs) are a vital strategy to enhance the bioavailability (BA) of formulations of poorly water-soluble compounds. However, these formulations have certain limitations, including in vivo drug precipitation, poor in vitro in vivo correlation due to a lack of predictive in vitro tests, issues in handling of liquid formulation, and physico-chemical instability of drug and/or vehicle components. To overcome these limitations, which restrict the potential usage of such systems, the supersaturable SEDDSs (su-SEDDSs) have gained attention based on the fact that the inclusion of precipitation inhibitors (PIs) within SEDDSs helps maintain drug supersaturation after dispersion and digestion in the gastrointestinal tract. This improves the BA of drugs and reduces the variability of exposure. In addition, the formulation of solid su-SEDDSs has helped to overcome disadvantages of liquid or capsule dosage form. This review article discusses, in detail, the current status of su-SEDDSs that overcome the limitations of conventional SEDDSs. It discusses the definition and range of su-SEDDSs, the principle mechanisms underlying precipitation inhibition and enhanced in vivo absorption, drug application cases, biorelevance in vitro digestion models, and the development of liquid su-SEDDSs to solid dosage forms. This review also describes the effects of various physiological factors and the potential interactions between PIs and lipid, lipase or lipid digested products on the in vivo performance of su-SEDDSs. In particular, several considerations relating to the properties of PIs are discussed from various perspectives.

Achyranthis radix Extract-Loaded Eye Drop Formulation Development and Novel Evaluation Method for Dry Eye Treatment

Recently, Achyranthis radix extract has been studied as a therapeutic agent for dry eye disease that occurs from fine dust. The aim of this study was the development of Achyranthis radix extract-loaded eye drop formulations using lubricants, generally used for artificial tear eye drops. Ecdysterone was used as a marker compound for Achyranthis radix extract and 1% Achyranthis radix extract solution contained 14.37 ± 0.04 μg/mL of ecdysterone. Before formulation studies, a new method was performed to evaluate pigmentation, which might be caused by eye drops of herbal extract. A comparative study of the water retention ability of each formulation and ability to prevent the death of conjunctival epithelial cells in dry conditions was conducted. Moreover, treatment of Achyranthis radix extract (USL) eye drop formulation exhibited a significant inhibitory effect on inflammation in a concentration-dependent manner. The long-term and accelerated stability tests showed that lubricants could contribute to the stability of herbal extracts in solution. In conclusion, hyaluronic acid showed a good effect on the development of eye drop formulation using Achyranthis radix extracts for treating dry eye disease.