Some OSes - like AIX - by default do not have a pkill command
Someone might have installed it from somewhere but its not native so do not assume it exists on your host.
If you are logged in as the user med, and you want everything down that this user runs,
kill -9 -1 is a pretty safe method. But only run it when the application stop script left things running. So wait a few min after stopping the app to run the command.
Please note that if you have zombie processes left over (app processes that are owned by 1), this command will still not kill them. Only a system reboot will.
If you have to restart your app often, its better to find out what is preventing your processes from terminating cleanly than to kill those leftover processes.