100% suggested rda is unlikely to be an issue. the most likely suggestion will be that the product be taken in 1/2 dose so that cuts it down ever farther. there are quite a few nutrients that interact with different medications, e & k and such, so it wouldnt have been wise to single out and not include any essential micronutrients based on their potential interactions with drugs.
2-4x is perfectly safe, not counting any interactions with medication. average lithium intake is ~.5-~3g per day mostly from grains and vegetables. i can probably help you get a good estimate on your dietary lithium intake if youre interested. i'll take note of your advice, if you can PM me the name of your drug & any studies you have that would be helpful.