The Sustained Effects on Tear Volume of Pilocarpine Hydrochloride in Gelatin by Hydrogel Administered by An Implant-mediated Drug Delivery System

Background: Pilocarpine hydrochloride is commonly prescribed to patients with dry mouth and eye using a frequent dosing schedule. The aim of this study was to evaluate the sustained effects of this highly soluble drug carried by a gelatin hydrogel, which was administered by an implant mediated drug delivery system (IMDDS). Methods: The IMDDS was installed in a total of 24 rabbits. After complete healing, pilocarpine hydrochloride was administered as 30 mg as raw powder (Group 1; n = 8), 30 mg in gelatin hydrogel (Group 2; n = 8), and 60 mg in gelatin hydrogel (Group 3; n = 8). The effects were evaluated by tear volume measured using the Schirmer tear test for 2 weeks after administration. Results: All 3 groups showed an increase in tear volume from the initial measurement at 1 hour. Group 1 exhibited this increase for 24 hours, while Groups 2 and 3 sustained this increase for 5 days and 7.5 days, respectively. Conclusion: When provided in gelatin hydrogel, highly water-soluble pilocarpine hydrochloride administered through IMDDS resulted in sustained effects with increased tear volume in normal rabbits.