The software listed above are good providing you have the funding to purchase licenses. There are a number of packages available that span freeware to commercial. For a rather long listing, please check out:
As Jun Shi already suggested you may find the SimCYP tool that is specifically designed for PBPK with modules and libraries including Cardiac Safety Simulator, Paediatric, Animal etc. so I include the link below;
Learn the math. Then implement it in your programmin language of choice. In addition to proprietary solutions (MATLAB, etc) I have also used R (fast, powerful, and free) and am currently working in Python (all the advantages of R, but easier to organize your source code).