Dear Ms. Martinez,
There is not a sinle dose of Lithium that would be regarded as normal. It varies greatly because people metabolize such chemicals in very individual ways. It will ne necessary to have the level of the medication monitored via periodic blood tests, to determine if the medication is within a therapeutic range. It's quite usual for Lithium to be prescribed at a dose of 300 mg three times daily and to increase from that point.
I think you've accidentally posted this in the wrong forum? Try to post in Mental Health.
You can search medhelp for information on Bipolar Disorder and lithium.
-P