Evaluation of mucoadhesive polymers in ocular drug delivery. I: Viscous solutions

The potential of a mucoadhesive polymer as an ophthalmic vehicle is evaluated within the rabbit. Precorneal clearance of a mucoadhesive polymer solution (Carbopol 934P) is compared to that of an equiviscous nonmucoadhesive poly(vinyl alcohol) solution (PVA) and buffer (PBS). The precorneal retention of the Carbopol 934P, as studied by lacrimal dacryoscintigraphy, is shown to be significantly greater (P < 0.05) than that of PVA, which, in turn, is significantly greater than that of PBS. The effect of the polymer solution on the bioavailability of pilocarpine is subsequently assessed by measuring the relative miotic response intensities produced by a 1% solution of the drug. Carbopol 934P solution produces a significant increase (P < 0.05) in bioavailability as compared to PVA and PBS. The bioavailability from PVA is significantly greater (P < 0.05) than that from PBS. Studies evaluating vehicle-drug association indicated no binding of the drug to the polymer.