What Alien47 has got me wondering: are you inquiring because you are interested in its effects for pleasure and recreation purposes or for a replacement - as Alien47 said - for alcohol?
If you are intrested in harm reduction, a decent dose of Kava will provide plenty of relaxation without the sloppiness of alcohol. It can be a heavy cns depressant. It is not recommended to mix moth alcohol or other depressant drugs. Kava can easily used recreationally, but can be used medicinally. Kava is a medication that deserves respect.
After seeing it on the booze traveler on the travel channel I tried some. It is calming however if you go to Wal-Mart and buy kava tea don't expect much calming. Lol. Also the kava tea at Wal-Mart tastes like shit. Lol
Yes, the numbness is because it's a sodium channel blocker. One of it's main method of actions is to work on ion channels such as sodium and calcium channels. As well as cannabinoid receptors. It has been shown not to have GABAergic activity as previously thought.