The objective of this study was to investigate the processability of hot-melt extrusion (HME) to formulate ocular inserts of valacyclovir hydrochloride and evaluate the in vivo bioavailability of the formulation. To optimize the formulation of this drug, different physical mixtures of the polymers and plasticizer were prepared. The physical mixture was extruded through a co-rotating twin-screw extruder, and the obtained ocular inserts were cut with dimensions of 4 mm × 2 mm × 1 mm to enhance the formulation instillation in the eye. Ocular inserts were evaluated for drug content, weight variation, uniformity of thickness, in vitro drug release, and in vivo drug bioavailability. The ocular inserts were thermally characterized using differential scanning calorimetry (DSC). The attributes observed for the ocular inserts were within the target specifications. The ocular inserts of valacyclovir hydrochloride were successfully prepared using the HME. They provided sustained drug release along with enhanced drug permeation when compared with the eyedrop solution and dissolve completely in 8 h. Additionally, the obtained results demonstrated that the formulation of ocular inserts of valacyclovir hydrochloride using HME was reproducible, robust, and effective method.
Keywords: acyclovir; antiviral; hot-melt extrusion; ocular drug delivery; ocular inserts.