To use tools like Multipath in zabbix, you have to check the sudo-settings for the zabbixuser.

Use visudo to change the permissions for zabbix.

Zabbix will not use a Terminal tty, so you should deactivate that in sudo... You can do this by comment the line Defaults requiretty out, or you put that line Defaults:zabbix !requiretty into the visudo-configfile. If you take method one, it is a globalsetting and no connection needs a tty. Method two will only deactivate that for the zabbix user. I recommend method two!

Now you can allow the commands you want to use with zabbix. According to the maxim: "as little as possible, as much as necessary" . So you can use a line like that:

zabbix ALL=NOPASSWD: /sbin/multipathd -k

If you want to use more Tools/Commands or even acces to files, you can put them after the command above, comma seperated.