Research on the comparison of the demethylvancomycin's diffusion-deposition characteristics in the ocular solid tissues of sustained subtenon drug delivery with subconjunctival injection

Treatment of Severe Acute Bacterial Keratitis in Rabbits Using Continuous Topical Ocular Instillation with Norvancomycin

Purpose

Efficacy of norvancomycin (NVCM) through continuous topical ocular instillation drug delivery (CTOIDD) system for treating severe acute bacterial keratitis infection with Staphylococcus aureus was investigated.

Methods

Rabbits with bacterial keratitis were treated using CTOIDD with NVCM (n=13), topical NVCM eye drops (n=11), and CTOIDD with saline (n=8). Clinical signs of keratitis in all groups were assessed consecutively for a week. Bacterial quantification of excised corneas was counted on the fourth and eighth days. Histopathologic examinations were performed to assess inflammatory cell infiltration on the eighth day.

Results

All signs of bacterial keratitis were alleviated in CTOIDD with NVCM according to criteria, and the CTOIDD-NVCM group had significantly less inflammation than CTOIDD-saline (p<0.05), and eye drop-NVCM (p<0.05). Two eyes in the eye drop-NVCM group, four eyes in the CTOIDD-saline group had corneal perforation (CP), while none of the rabbits showed CP in the CTOIDD-NVCM group. Bacterial counts were significantly less in the CTOIDD with NVCM group in comparison to the eye drop-NVCM (p<0.05), and CTOIDD-saline (p<0.05) groups. Severe inflammation and marked inflammatory cell infiltration were found in histopathologic examinations in the CTOIDD-saline and eye drop-NVCM groups, while significantly less inflammation was documented in the CTOIDD-NVCM (p<0.05) group.

Conclusion

CTOIDD with NVCM effectively reduced the severity and treated acute bacterial S. aureus keratitis infection in a rabbit model. The presented approach of CTOIDD with NVCM appears to be a promising therapeutic approach for severe acute bacterial keratitis.

Pranoprofen quantification in ex vivo corneal and scleral permeation samples: Analytical validation

The investigation of the ocular permeability and/or distribution of pranoprofen (PF), a non-steroidal antiinflamatory drug, demands for the selective analysis of its transit through specific ocular membranes. Therefore, customised ex vivo permeation experiments through external ocular tissues (cornea and sclera) have been validated for this drug in addition to its HPLC-UV quantification following standard bioanalytical guidelines. Chromatographic conditions consist of an isocratic system to elute the drug with a C18 column with UV detection at 245 nm. Precision, expressed as the relative standard deviation (% RSD), ranged between 4.89 and 0.79% (intra-day) and between 9.02 and 2.14% (interday). Accuracy ranged between 5.15 and -1.92% in intra-day experiments and between 6.25 and -4.89% in inter-day experiments. Drug recovery from tissue samples was reproducible around 90% and considered satisfactory to adequately assess drug levels in target tissues. Results indicate that the procedure is valid for the quantitation of PF in those ophthalmic samples in the range of 6.5 μg/mL to 100 μg/ml. As a proof of concept, PF permeation profiles through porcine cornea and sclera with vertical diffusion cells have been generated and analyzed. Pilot experiments demonstrate its applicability to investigate permeation levels of PF from 22.31 μg/cm² (about a 20% of the dose) until 500 μg/cm² if required. Additionally, real tissue-retention samples were also generated to verify the goodness of this experimental setup.