Bupropion ER 300mg is an extended-release tablet used primarily to treat major depressive disorder and as an aid for smoking cessation. It works by inhibiting the reuptake of norepinephrine and dopamine, which helps improve mood and reduce cravings. The extended-release formulation allows for once-daily dosing, ensuring more stable blood levels and consistent therapeutic effects throughout the day. This dosage is typically used to provide adequate symptom relief while minimizing side effects, offering improved patient adherence compared to immediate-release versions. The medication is often chosen for its efficacy with a relatively favorable side effect profile.