I have been taking Lithium for almost a year and a half and when i was put on it I was on the depakote, which wasn't working. I worked almost immediately I was released from hospital shrtly there after and I haven't been back since.
To give you some reference on Lithium the greek or Roman physicians would send what they called "crazy" patients to bathed in the hot springs in the mountains. We know have come to knwo that the springs are rich in Lithium Salts so Even in small absorbed doses Lithium is quite effective. I have had little to no problem with the drug. Although the blood test to come to be a pain sometime, but you get used to them as I sure you have with the depakote.

Lithium is a salt not a chemical so it sort of replaces the sodium in your blood and because your body needs salt it can be accessed better versus getting used to a chemical or sorts like depakote that takes time to cause a reaction.

Good luck,
Adam