Depression self-initiated treatments

A 38-year-old divorced woman who lived alone visited a psychiatrist because she was depressed. Her symptoms included low self-esteem, with frequent ruminations on her worthlessness, and hypersomnia. She was hyperphagic and complained that her limbs felt heavy. An initial diagnosis was made of a major depressive disorder with atypical symptoms. Treatment was initiated with amitriptyline, but after 2 months the patient had not improved significantly. Which one of the following drugs is MOST likely to have therapeutic value in this depressed patient ... 

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