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Ocular tolerability and in vivo bioavailability of poly(ethylene glycol) (PEG)-coated poly(ethyl 2-cyanoacrylate) nanosphere-encapsulated acyclovir.

Abstract

Acyclovir-loaded poly(Et 2-cyanoacrylate) (PECA) nanospheres were prepd. by an emulsion polymn. process in the micellar phase and characterized. The influence of the presence of nonionic surfactants as well as other substances [i.e., 2-hydroxypropyl-b-cyclodextrin (HP-b-CyD) and PEG], on formulation parameters and loading capacity was investigated. In particular, the presence of PEG resulted in an increase of mean size and size distribution. To obtain PEG-coated PECA nanospheres with a mean size of <200 nm, Pluronic F68 at concns. >1.5% should be used during prepn. The presence of PEG also resulted in a change in zeta potential, from -25.9 mV for uncoated nanospheres to -12.2 mV for PEG-coated PECA nanospheres. The presence of HP-b-CyD elicited an increase of nanosphere size and size distribution, but zeta potential was not influenced. In vitro drug release from nanospheres was detd. in both phosphate buffer (pH 7.4) and plasma. The presence of HP-b-CyD and PEG did not influence the acyclovir release rate in plasma. In the case of release in phosphate buffer, PEG-coated nanospheres showed a slower release. Ocular tolerability of PEG-coated PECA nanospheres was evaluated by the in vivo Draize test. This colloidal carrier was well tolerated, eliciting no particular inflammation at the level of the various ocular structures. In vivo ocular bioavailability was evaluated by instilling 50 mL of the acyclovir-loaded nanospheres only once in the conjunctival sac of rabbit eyes. At various time intervals, aq. humor acyclovir content was detd. by high-performance liq. chromatog. Acyclovir-loaded PEG-coated PECA nanospheres were compared with an aq. soln. of the drug and a phys. mixt. of acyclovir nanospheres. The acyclovir-loaded PEG-coated PECA nanospheres showed a significant increase of drug levels (25-fold) in aq. humor compared with the free drug or the phys. mixt. This finding is probably due to an improved ocular mucoadhesion of PEG-coated PECA nanospheres

Autori

PUGLISI - Giovanni

Altri Autori

Fresta Massimo
Fontana Giacomo
Bucalo Claudio
Cavallaro Gennara
Giammona Gaetano