PHYSICAL CHARACTERIZATION OF IN SITU OPHTHALMIC GEL: A CONCISE REVIEW

In situ ophthalmic gel is a type of eye drug preparation that has a higher bioavailability value and has a longer contact time with maximum therapeutic effect and with minimal side effects compared to conventional eye preparations. The preparation of ophthalmic in situ gel is required characterization to make sure that the prepared preparations meet the standards and are safe when used. This journal review aims to look at the methods used in characterizing physical properties in in situ ophthalmic gel formulations with different active substances such as rheology studies, organoleptic tests, pH, clarity, and gelling capacity. In order to get the best formulation of in situ ophthalmic gel preparations so as to provide maximum therapeutic effect.

Sustained ophthalmic delivery of pH triggered Cromolyn sodium in situ gel

The research study intends to formulate pH triggered in situ gel of Cromolyn sodium composed of Polyacrylic acid (carbopol 934) polymer in combination with Hydroxypropyl Methylcellulose (HPMC K4M) polymer at 1:1, 1.5:1, 2:1 molar ratio by utilizing pH trigger method. Formulations were evaluated for pH, viscosity, gelling capacity, drug content and in vitro drug release. Results of Carbopol 934 and HPMC K4M based in situ gelling systems at 1:1, 1.5:1, 2:1 shown that the formulations were fluid state at room temperature in a formulated pH (pH 4.5) and went through fast progress into the viscous gel phase at the pH of the tear fluid 7.4. The viscosity of formulated pH triggered in situ gel at 2:1 molar ratio shown excellent result compares to 1:1, 1.5:1 molar ratio. The in vitro drug release of the developed in situ gelling formulations at 1:1, 1.5:1, 2:1 molar ratios increases the contact time and showed a non – fickian diffusion type of release behavior with 94.45%, 83.26%, 70.48% respectively over 8 hours periods compared with that of marketed formulation that shows 99.4% over 4 hours. Thus, the developed system at 2:1 molar ratio acts as a viable alternative to conventional eye drops and also prevent the rapid drainage.

Thermosensitive Poly(DHSe/PEG/PPG Urethane)-Based Hydrogel Extended Remdesivir Application in Ophthalmic Medication

The spread of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused the coronavirus disease 2019 (COVID-19) outbreak beginning in March 2020. Currently, there is a lack of suitable dose formulations that interrupt novel coronavirus transmission via corneal and conjunctival routes. In the present study, we developed and evaluated a thermosensitive gelling system based on a selenium-containing polymer for topical ocular continuous drug release. In detail, di-(1-hydroxylundecyl) selenide (DHSe), poly(ethylene glycol) (PEG), and poly(propylene glycol) (PPG) were polymerized to form poly(DHSe/PEG/PPG urethane). The polymer was used to carry poorly water-soluble remdesivir (RDV) at room temperature to form the final thermosensitive in situ gel, which exhibited a typical sol-gel transition at 35 °C. The formed polymer was further characterized by rheology, thermology, and scanning electron microscopy. In vitro release studies and in vivo retention and penetration tests indicated that the thermogel provided the prolonged release of RDV. The RDV-loaded in situ gel was proven to be non-biotoxic against human corneal epithelial cells, with good ocular tolerance and biocompatibility in rabbit eyes.

In-Situ Ocular Gel Pharmaceutical Delivery System: A Recent Review

Ocular Drug Delivery has been a key challenge and attractive field for the pharmaceutical scientist due to peerless anatomy and physiology of eye. Glaucoma, dry eye syndrome, keratitis, endophthalmitis, trachoma, and conjunctivitis are just a few of the conditions that can affect the eye. In order to accomplish efficient ocular treatment within the eye, At the point of action, an appropriate supply of active substances must be given and sustained. Due to fast precorneal medication loss, traditional treatment has a low bioavailability. The bioavailability of a medicine is also influenced by static and dynamic barriers. To address the limitations of traditional treatment, significant efforts are being made to develop innovative medication systems for ocular delivery. When a drop is injected into the eye, it goes through a sol-gel transition and forms a cul-de-sac. The in-situ gel system, which comprises thermally triggered, pH triggered, and ion cross linking systems, is the subject of this review. It includes a step-by-step procedure for preparing the pH-triggered system as well as assessment parameters. Keywords: Conventional dosage form, Anatomy and physiology in eye, In-situ gel.

A Recent Overview: In Situ Gel Smart Carriers for Ocular Drug Delivery

Delivery of the drug to the ocular area is blocked by the protective layers covering the eyes; it has always been a major problem to find effective bioavailability of the active drug in the ocular area due to the short duration of precorneal majority ocular stay. Direct delivery systems combine as well as oil, solution, and suspension, as a result, many delivery systems are not able to effectively treat eye diseases. Many works have been done and are being done to overcome this problem one of which is to use in-situ to build polymeric systems. Ocular In-situ gelling systems are a new class of eye drug delivery systems that are initially in solution but are quickly transformed into a viscous gel when introduced or inserted into an ocular cavity where active drugs are released continuously. This sol-to-gel phase conversion depends on a variety of factors such as changes in pH, ion presence, and temperature changes. Post-transplanting gel selects viscosity and bio-adhesive properties, which prolongs the gel's stay in the ocular area and also releases the drug in a long and continuous way unlike conventional eye drops and ointments. This review is a brief overview of situ gels, the various methods of in situ gelling systems, the different types of polymers used in situ gels, their gel-based methods, and the polymeric testing of situ gel. Keywords: In-situ gel, Polymers, and ion triggered in-situ gel, Mechanism, Evaluation parameters