Comprehensive evaluation of formulation factors for ocular penetration of fluoroquinolones in rabbits using cassette dosing technique.
OBJECTIVE
Corneal permeability of drugs is an important factor used to assess the efficacy of topical preparations. Transcorneal penetration of drugs from aqueous formulation is governed by various physiological, physiochemical, and formulation factors. In the present study, we investigated the effect of formulation factors like concentration, pH, and volume of instillation across the cornea using cassette dosing technique for ophthalmic fluoroquinolones (FQs).


MATERIALS AND METHODS
Sterile cocktail formulations were prepared using four congeneric ophthalmic FQs (ofloxacin, sparfloxacin, pefloxacin mesylate, and gatifloxacin) at concentrations of 0.025%, 0.5%, and 0.1%. Each formulation was adjusted to different pH ranges (4.5, 7.0, and 8.0) and assessed for transcorneal penetration in vivo in rabbit's cornea (n=4 eyes) at three different volumes (12.5, 25, and 50 μL). Aqueous humor was aspirated through paracentesis after applying local anesthesia at 0, 5, 15, 30, 60, 120, and 240 minutes postdosing. The biosamples collected from a total of 27 groups were analyzed using liquid chromatography-tandem mass spectroscopy to determine transcorneal permeability of all four FQs individually.


RESULTS
Increase in concentration showed an increase in penetration up to 0.05%; thereafter, the effect of concentration was found to be dependent on volume of instillation as we observed a decrease in transcorneal penetration. The highest transcorneal penetration of all FQs was observed at pH 7.0 at concentration 0.05% followed by 0.025% at pH 4.5. Lastly, increasing the volume of instillation from 12.5 to 50 μL showed a significant fall in transcorneal penetration.


CONCLUSION
The study concludes that formulation factors showed discernible effect on transcorneal permeation; therefore, due emphasis should be given on drug development and design of ophthalmic formulation.
['Sharma|Charu|C|', 'Biswas|Nihar R|NR|', 'Ojha|Shreesh|S|', 'Velpandian|Thirumurthy|T|']
D000818:Animals D002626:Chemistry, Pharmaceutical D003315:Cornea D004305:Dose-Response Relationship, Drug D024841:Fluoroquinolones D006863:Hydrogen-Ion Concentration D009883:Ophthalmic Solutions D010539:Permeability D011817:Rabbits
transcorneal penetration ophthalmic in vivo antibacterial