Background: Herpes keratitis is the most common infectious cause of blindness in the developed
world. It may be treated by acyclovir (ACV), however this antiviral drug is poorly soluble
with low ocular bioavailability requiring high and frequent dosing. Nanostructured lipid carriers
(NLCs) were investigated to improve the ocular bioavailability of ACV by enhancing corneal penetration
as well as prolonging the exposure of infected cells to the antiviral agent.
Methods: Cell uptake studies, ex vivo tolerance and cell uptake efficacy as well as in vivo corneal permeation of the developed
lipid based formulations were investigated. NLCs were fabricated by the hot microemulsion technique and coated
with 0.5% w/v chitosan. NLCs were capable of increasing the cell uptake of encapsulated fluorescein and ACV as examined
by fluorescence microscopy and high performance liquid chromatography (HPLC) respectively.
Results: When entrapped in NLCs, the antiviral efficacy of ACV was increased by 3.5 fold after 24 hrs of exposure. The
in vivo corneal permeation of the formulation was studied on Albino rabbits with NLCs capable of increasing the corneal
bioavailability by 4.5 fold when compared to a commercially available ACV ophthalmic ointment.
Conclusion: NLCs enhanced the ocular bioavailability and antiviral properties of ACV through cell internalisation, sustained
release, and increased corneal permeation.