I have been taking 300mg XL Bupropion for 5 years and it has been working fine until the last few weeks. I contacted my doctor and asked what medication might help this blip in experiencing depression of late. I didn't receive a call back but did get notice that he put in a prescription for me to pick up for 150mg XL Bupropion. Does anyone know why he thinks this will help relieve my depression of late?