Compounds and combinations thereof for treating neurological and psychiatric conditions

A method of treating agitation associated with dementia due to Alzheimer's disease in a human patient in need thereof comprising:

• 1) orally administering with or without food a first dosage form once daily for one week to the human patient, then administering with or without food the first dosage form twice daily to the human patient for one week;
• and 2) then orally administering with or without food a second dosage form twice daily to the human patient thereafter, for a total of at least five week;
• wherein the human patient is not a CYP2D6 poor metabolizer, and does not have moderate renal impairment;
• wherein the first and second dosage forms are bilayer tablets;
• wherein the first dosage form comprises about 30 mg of dextromethorphan hydrobromide, or a molar equivalent amount of another salt form of dextromethorphan or the free base form of dextromethorphan, about 105 mg of bupropion hydrochloride, or a molar equivalent amount of another salt form of bupropion or the free base form of bupropion, and a polymer;
• and
• wherein the second dosage form comprises about 45 mg of dextromethorphan hydrobromide, or a molar equivalent amount of another salt form of dextromethorphan or the free base form of dextromethorphan, and about 105 mg of bupropion hydrochloride, or a molar equivalent amount of another salt form of bupropion or the free base form of bupropion.