Using Drug Augmentation to Treat Obsessive Compulsive Disorder Patients Who Did Not Respond to Previous Treatment

This will be a controlled, randomized, double-blind and double-dummy study on the treatment augmentation strategy for obsessive compulsive disorder patients non-respondent to first line pharmacological treatment. The investigators will compare: fluoxetine maintenance at maximum dosage for additional 12 weeks; the association of fluoxetine with quetiapine; and the association of fluoxetine with clomipramine.