In situ-gel formulation of Levofloxacin eye drops, and in vitro‬‬ ‫‪evaluation ‬‬‬‬‬‬‬‬‬‬‬‬

The ocular drug delivery system is one of the most challenging yet important systems currently. Conventional pharmaceutical dosage forms such as: solutions, suspensions and ointments have the property of short precorneal residence time and poor bioavailability and that is due to natural eye defense mechanisms such as: Blinking, tearing reflex and exerting any type of foreign bodies including drugs. Hence, only 5% of the original desired dose is delivered to its target. This research aims to prepare eye drops of levofloxacin hemihydrate that gels when applied in the eye as a result of temperature difference between the external environment and the eye. The Cold method is used to prepare these solutions, different polymers are employed: poloxamer 407 as a temperature sensitive polymer, sodium alginate as an ion activated polymer, Hydroxypropyl methylcellulose (HPMC K-100) as a mucoadhesive polymer and polyethylene glycol (PEG 6000) as a gelling temperature modifier for the formula. The main goal for this formula is to improve the drug's bioavailability and achieve sustained drug release resulting in increased patient compliance. The physical and chemical properties of the resulting in-situ gel solutions were evaluated in terms of: clarity, drug content, Ph, solution viscosity, gelling temperature and gelling capacity and in vitro drug release studies were performed using a dialysis bag. Drug-polymer interactions were investigated by Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC) and the effect of in situ gel polymers concentration on drug release were evaluated. As a result: all formulations had a transparent, clear and yellow light color. All formulations were of a suitable PH degree so as not to cause irritation to the eye, and suitable physical properties for ocular administration of such forms were acquired. The formulas p4, p7, p8 gave sustained release within 8 and 10 hours. FTIR and DSC studies did not show any evidence of interaction between the drug and the polymers.