Hi there,
I am on Lithium (for the past year) and I take 225mg in the morning and 450mg at night.
Lithium is the best meds for Bipolar. I hope it works for her.
Your sister's medicine is probably where it needs to be. She can talk with her dr if she is experiencing any problems.
Depends on your sister. If it's helping her, than it's a useful dose.