Abstract
Purpose: :
The objective of this study is to develop and characterize polymeric nanoparticles of stereoisomeric peptide prodrugs of acyclovir (L-val-L-val-ACV, L-val-D-val-ACV, D-val-L-val-ACV, and D-val-D-val-ACV) for the treatment of ocular herpes simplex keratitis.
Methods: :
Stereoisomeric peptide prodrugs of acyclovir were screened for antiviral efficacy, bio-reversion (cell homogenates and ocular tissues), transport across rabbit cornea, and cytotoxicity. The best prodrugs were chosen for formulation into nanoparticles. Nanoparticles were prepared by w/o/w emulsion method utilizing various grades of PLGA. These nanoparticles were characterized for entrapment efficiency, surface morphology, size distribution and in vitro release characteristics. Further the effect of thermosensitive gels on the release of prodrugs from nanoparticles was also studied.
Results: :
L-val-L-val-ACV and L-val-D-val-ACV were considered to be the optimum in terms of enzymatic stability, in ocular tissues and cell homogenates, invitro uptake, transport across rabbit cornea, and cytotoxicity. There was no cytotoxicity observed with these prodrugs on SIRC cell line. The entrapment efficiency of L-val-L-val-ACV was found to be 59.7% with a drug loading of 5.5%. The size of the nanoparticles was found to be 164.9 nm with a polydispersity of 0.018. SEM studies revealed the smooth and spherical surface of nanoparticles. The burst release of drug from the nanoparticles was successfully minimized when suspended in PLGA-PEG-PLGA thermosensitive gels.
Conclusions: :
These novel nanoparticulate systems suspended in thermosensitive gels may provide sustained delivery of the prodrug following topical administration.
Keywords: antiviral drugs • cornea: epithelium • keratitis