**Question:** Drug of choice in Obsessive compulsive disorder is

A. Fluoxetine
B. Fluoride
C. Clonazepam
D. Methotrexate

**Correct Answer:** A. Fluoxetine

**Core Concept:** Obsessive-compulsive disorder (OCD) is a psychiatric disorder characterized by persistent and recurrent thoughts (obsessions) and behaviors (compulsions) that the individual feels driven to perform due to internalized anxiety or distress. OCD significantly impacts daily functioning and quality of life.

**Why the Correct Answer is Right:** Fluoxetine is a selective serotonin reuptake inhibitor (SSRI) that targets the underlying neurochemical imbalances in OCD. In OCD, there is a decrease in serotonin neurotransmission in the prefrontal cortex and orbitofrontal cortex, which leads to the symptoms. Fluoxetine increases serotonin levels in these areas, thereby reducing obsessive and compulsive symptoms.

**Why Each Wrong Option is Incorrect:**

A. Fluoride (Choice B) is an essential element required for dental health and bone mineralization but has no role in treating OCD.

C. Clonazepam (Choice C) is a benzodiazepine primarily used for its anxiolytic and sedative properties. It does not address the serotonin imbalance in OCD and can worsen symptoms.

D. Methotrexate (Choice D) is a chemotherapy drug used for treating cancer and autoimmune disorders. It is not a treatment for OCD due to its potential toxicity and lack of targeting serotonin neurotransmission.

**Clinical Pearl:** Obsessive-compulsive disorder (OCD) is a treatable condition, and the first-line therapy involves selective serotonin reuptake inhibitors (SSRIs), such as Fluoxetine (Prozac), Sertraline (Zoloft), or Fluvoxamine. These medications gradually increase the availability of serotonin in the brain, reducing obsessive-compulsive symptoms.

**Core Concept:** Selective serotonin reuptake inhibitors (SSRIs) are the first-line therapy for treating OCD due to their ability to increase serotonin levels in the prefrontal cortex and orbitofrontal cortex, which are primarily affected in OCD. SSRIs like Fluoxetine, Sertraline, or Fluvoxamine are used to treat OCD and improve its associated symptoms.