**Question:** Which of the following SSRI is used only in the management of OCD?

A. Paroxetine
B. Fluoxetine
C. Escitalopram
D. Fluoromethyltryptophan

**Core Concept:** Selective Serotonin Reuptake Inhibitors (SSRIs) are a class of antidepressants that work by increasing the availability of serotonin in the brain. They are commonly used in the treatment of various psychiatric disorders, including depression, anxiety disorders, and obsessive-compulsive disorder (OCD).

**Why the Correct Answer is Right:** Paroxetine is a specific SSRI that is primarily used for the treatment of OCD. Unlike other SSRIs, its specific affinity for the serotonin reuptake transporter makes it more effective in treating OCD symptoms.

**Why Each Wrong Option is Incorrect:**

B. Fluoxetine: Although it is an SSRI, fluoxetine is used for the treatment of various psychiatric disorders, including depression and anxiety disorders. Its usage in the management of OCD is not as exclusive as paroxetine.

C. Escitalopram: Similar to fluoxetine, escitalopram is also used for the treatment of depression and anxiety disorders. Its efficacy in treating OCD is not as strong as paroxetine.

D. Fluoromethyltryptophan: This option is incorrect because it is a precursor to serotonin and not an SSRI or antidepressant. It is not used in the treatment of psychiatric disorders.

**Clinical Pearl:** The core principle of SSRI usage lies in their ability to selectively inhibit the reuptake of serotonin, which helps in improving mood and reducing symptoms of psychiatric disorders. In the context of OCD treatment, paroxetine stands out due to its higher affinity for serotonin reuptake compared to other SSRIs.

**Correct Answer:** Paroxetine