Bupropion is neither an SSRI (selective serotonin reuptake inhibitor) nor an SNRI (serotonin-norepinephrine reuptake inhibitor). Instead, it belongs to a class of medications known as atypical antidepressants or dopamine and norepinephrine reuptake inhibitors (DNRI).
While SSRIs and SNRIs work by increasing the levels of serotonin and/or norepinephrine in the brain, bupropion works by blocking the reuptake of dopamine and norepinephrine, which increases their availability in the brain. This mechanism of action is different from that of SSRIs and SNRIs, which is why bupropion is classified as an atypical antidepressant.
It is important to note that although bupropion is not an SSRI or an SNRI, it is still an effective antidepressant and may be used alone or in combination with other medications to treat depression and other mood disorders. As with all medications, it should only be taken as prescribed by a healthcare provider and under their supervision.