In situ ophthalmic gel forming systems of poloxamer 407 and hydroxypropyl methyl cellulose mixtures for sustained ocular delivery of chloramphenicole: optimization study by factorial design

Ophthalmic In Situ Gels with Balsam Poplar Buds Extract: Formulation, Rheological Characterization, and Quality Evaluation

“…In vitro diffusion study of the phenolic compounds of the prepared formulations was performed using a Franz diffusion cell [ 83 ]. The results of the tests confirmed the data obtained by other scientists—the released amounts of the active compounds depended on the amount of gelling agent [ 35 , 46 ]. The greater the concentration of the gelling agent in the formulation, the slower the rate of release of the active compounds.…”

“…In view of the fact that the bioavailability of eye drops can be improved by increased precorneal residence time [ 60 ], in situ gels were chosen for production. In situ gels, due to their viscosity, slow down the speed of drug elimination from the eye [ 46 ]. An important step in the formulation of in situ gels is the choice of excipients, which could ensure the stability of preparations without changing the activity of bioactive ingredients, and be non-irritant—especially when used locally on the surface of the eye [ 61 , 62 ].…”

“…Poloxamer 407, chosen for the production of gels, is often used for ophthalmic preparations as a substance resistant to temperature changes [ 63 , 64 ]. Poloxamer 407 is used for the production of in situ gels, but used alone it has few mucoadhesive properties, while too large a concentration of it can cause hyperglycemia in the eye [ 46 , 65 ]. In order to avoid these negative properties, poloxamer 407 is combined with cellulose derivatives, such as HPMC, usually used from 0.5 to 3% ( w / v ) [ 35 , 66 ].…”

“…Having reached suitable concentrations of polymers, suitable gelation temperatures for ophthalmic in situ gel preparations can also be reached. Propylene glycol was used in eye drop compositions based on the work of Kurniawansyah et al [ 46 ]. The scientific literature describes how substances such as sodium chloride or sodium dihydrogen phosphate lower gelation temperatures by forming strong crosslinks with poloxamer, while other substances such as ethanol or propylene glycol, with weaker hydrogen bonds, may weaken bonds and can increase gelation temperatures [ 67 ].…”

“…In the preparation of the in situ gels, the poloxamer 407 and HPMC gels were mixed with a magnetic stirrer to form a homogeneous structure. Next, 10% ( w / v ) propylene glycol and 10% ( w / v ) [ 46 ] L1 were added dropwise to the formulations, and the gels were mixed to form a homogeneous structure. All experimental formulations were stored in the refrigerator (5 °C).…”