In order to improve the drug availability after intravitreal administration, the present study tries to prepare solid lipid nanoparticles (SLNs) containing diclofenac as a novel drug delivery system. These nanoparticles were compared to conventional formulation in animal model after intravitreal injection.

In this experimental study, 18 albino rabbits were included. In the right eyes of all rabbits, SLNs containing diclofenac (0.3 mg drug) were intravitreally injected. On the left eyes of the rabbits, commercial form of diclofenac (0.3 mg drug) was injected. One, four, twelve, twenty four, and forty eight hours after injection, vitreous and aqueous humor samples were obtained in all cases. Then, the concentration of diclofenac sodium was evaluated in all samples.

Size of nanoparticles was around 170 nm after preparation. Drug concentration in eyes injected by SLNs was significantly higher than that of left eyes injected by commercial product up to 4 hours after intravitreal injection (P<0.05). Diclofenac was quantified in samples up to 48 hours after intraocular injection. Four hours after intravitreal injection, the concentration of diclofenac in vitreous and aqueous humor of eyes receiving SLNs was respectively 2.5 and 6.5 times higher than that of eyes injected by commercial form of drug. Also, we found that although the drug was intravitreally injected, it has been found in the aqueous humor in a significant concentration.

Here, we demonstrate the potential of SLNs as a carrier of diclofenac for intraocular injection in order to prevent the systemic effects of the drug, increase the injection intervals, and improve the patient compliance.