Improved ocular penetration of gentamicin by mucoadhesive polymer polycarbophil in the pigmented rabbit.

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.