Presented at ACoP14. This project is dedicated to integrating parameter uncertainty into pharmacometric simulations, which plays a crucial role in making informed decisions in drug development. Initially, the metrumrg package in R was instrumental for simulating both fixed and random effect parameters. However, this package has since been deprecated. Consequently, the primary objective was to create a new R package named simpar. This new package aimed to retain the essential functionalities of metrumrg while expanding its capabilities. The overarching goal was to significantly enhance the support for incorporating parameter uncertainty into pharmacometric simulations, thereby aiding more comprehensive and accurate decision-making processes in this field.