Combination of dextromethorphan and bupropion for treating depression

A method of treating major depressive disorder, comprising administering a drug combination to a human being in need thereof, wherein the drug combination comprises:

• bupropion, in an amount that is about 105 mg of bupropion hydrochloride, or a molar equivalent amount of a bupropion in a free base or another salt form, wherein the bupropion is administered once a day for the first three days and twice a day thereafter for at least 11 days;
• and
• dextromethorphan, in an amount that is about 45 mg of dextromethorphan hydrobromide, or a molar equivalent amount of a dextromethorphan in a free base or another salt form, wherein the dextromethorphan is administered once a day for the first three days and twice a day thereafter for at least 11 days;
• wherein the human being selected for (a) being of Asian descent;
• (b) receiving prior first line treatment in their current major depressive episode, (c) having a Clinical Global Impression-Severity score that is at least about 4, or (d) being male;
• wherein the human being experiences a greater reduction in Montgomery-Åsberg Depression Rating Scale (MADRS) score after receiving the drug combination, as compared to what would be experienced from receiving the same amount of the bupropion alone.