Currently on 300mg bupropion sr - dr advised going to 450mg 3 pills daily. what shd b the time interval in hours btw taking the pills?

Depends.: Since it is a sustained release medication, you can take it all at once or you can take it two in the morning and one after lunch. It is an "energizing" antidepressant because it is a Dopamine agonist.

Wellbutrin (bupropion): There should be approximately 8 hours between doses of wellbutrin (bupropion) sr. Wellbutrin (bupropion) xl is usually taken all at once in the morning. Max dose for wellbutrin (bupropion) sr is 400mg in a divided does and max for wellbutrin (bupropion) xl is 450mg in one dose. Take care.