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Improved ocular penetration of gentamicin by mucoadhesive polymer polycarbophil in the pigmented rabbit
1Department of Pharmaceutical Sciences, University of Southern California School of Pharmacy, Los Angeles 90033.
Purpose:
To investigate whether polycarbophil, a mucoadhesive polymer of the poly(acrylic acid) type, would improve the ocular delivery of topically applied gentamicin.
Methods:
Two gentamicin formulations of this polymer (neutralized versus non-neutralized) and an aqueous control formulation in saline were administered to the pigmented rabbit eye. Drug concentrations in plasma, as well as in cornea, bulbar conjunctiva, anterior sclera, iris-ciliary body, aqueous humor, and vitreous humor, were measured by fluorescence polarization immunoassay.
Results:
Both polymeric formulations increased the uptake of gentamicin by the bulbar conjunctiva two times. Drug penetration into the aqueous humor was observed with only the non-neutralized polymer, probably occurring via the conjunctival-scleral pathway facilitated by intensified contact between the mucoadhesive polymer and the underlying bulbar conjunctiva.
Conclusion:
Polymers of the poly(acrylic acid) type are potentially useful for improving topical antibiotic drug delivery, particularly when irritancy potential due to low pH can be overcome.