Delivery of antibiotics to the eye using a positively charged polysaccharide as vehicle

Abstract

The positively charged polysaccharide chitosan is able to increase precorneal residence time of ophthalmic formulations containing active compounds when compared with simple aqueous solutions. The purpose of the study was to evaluate tear concentration of tobramycin and ofloxacin after topical application of chitosan-based formulations containing 0.3% wt/vol of antibiotic and to compare them with 2 commercial solutions: Tobrex® and Floxal®, respectively. The influence of the molecular weight, deacetylation degree, and concentration of 4 different samples of chitosan on pharmacokinetic parameters (area under the curve values [AUC eff ] and time of efficacy [t eff ]) of tobramycin and ofloxacin in tears was investigated over time. It was demonstrated that the 2 chitosan products of high molecular weight (1350 and 1930 kd) and low deacetylation degree (50%) significantly increased antibiotic availability when compared to the controls, with AUC eff showing a 2-to 3-fold improvement. The time of efficacy of ofloxacin was significantly increased from about 25 minutes to 46 minutes by the chitosan of higher Mw (1930 kd) at a concentration of 0.5% wt/vol, whereas a similar performance was achieved by a chitosan of low Mw (580 kd) at a concentration of 1.5% wt/vol in the case of tobramycin.

Formulation and in Vivo Evaluation of Acyclovir Loaded Chitosan Nanoparticles for Ocular Delivery

“…Further, the positively charged chitosan is able to increase the precorneal residence time of ophthalmic formulations containing active compounds when compared with simple aqueous solution. [34] Stability studies Based on the in-vitro and in-vivo performance, the formulation F-9 was selected for short-term stability studies. The in-vitro release profile of formulation F-9 after 90 days of stability testing at different storage conditions were compared with the previous data of F-9; it was observed that there were no significant changes in drug release.…”

Novel mucoadhesive polysaccharide isolated from Bletilla striata improves the intraocular penetration and efficacy of levofloxacin in the topical treatment of experimental bacterial keratitis

“…Several drug delivery systems have been developed to prolong the contact time between antimicrobial drugs and corneal tissues, thus potentially enhancing the intraocular delivery of ophthalmic medications [6] . Among these, mucoadhesive polymers have been reported to be used in order to improve the intraocular penetration of ofloxacin, tobramycin and gentamicin [6–9] …”

Chitosan as an ocular drug delivery vehicle for vancomycin

“…After applying one drop containing 25 lL of vancomycin 50 mg/mL into the lower conjuctival eye sac, taking care to avoid spillage, tear samples were taken using 2.0 lL calibrated glass capillaries (Drummond Scientific Co.) as described by Felt et al 19 Tear samples were collected after 0, 30, 60, 90, and 120 min. Each formulation was tested on six rabbit eyes.…”

“…19 Thus, the mucoadhesive nature of chitosan can control the clearance of vancomycin by slowing down the elimination of the drug by the lachrymal flow.…”