A 28-year-old woman from Delhi presents with a 3-year history of intrusive thoughts about contamination from dirt and germs. She spends 2–3 hours daily washing her hands and taking multiple showers, which temporarily relieves her anxiety but interferes with her work as a software engineer. She recognizes these thoughts are irrational and excessive, but feels unable to resist the urges. She has tried to stop the compulsions on her own without success. Mental status examination shows mild anxiety but no psychotic features. What is the most appropriate first-line pharmacological intervention for this patient?

Explanation

## Diagnosis and Rationale **Key Point:** This patient meets DSM-5 criteria for Obsessive-Compulsive Disorder (OCD): presence of obsessions (intrusive contamination thoughts) and compulsions (excessive washing/showering) that are time-consuming (>1 hour daily), cause significant distress, and are recognized as excessive by the patient. ## First-Line Pharmacotherapy **High-Yield:** SSRIs are the first-line pharmacological agents for OCD. Sertraline is preferred in many guidelines due to: - Efficacy in OCD (FDA-approved) - Favorable side-effect profile - Rapid onset (2–4 weeks) - Dosing flexibility - Better tolerability than tricyclics in younger patients **Clinical Pearl:** Higher doses are required for OCD compared to depression. Sertraline 150–200 mg/day is the therapeutic range; lower doses (50 mg) used for depression are often insufficient for OCD. ## Comparison of First-Line Agents | Agent | Status in OCD | Advantages | Disadvantages | | --- | --- | --- | --- | | Sertraline (SSRI) | First-line | FDA-approved, good tolerability, faster onset | Requires 4–6 weeks for full effect | | Paroxetine (SSRI) | First-line | FDA-approved, potent serotonergic activity | Higher discontinuation syndrome | | Fluoxetine (SSRI) | First-line | FDA-approved, long half-life | Activating, may worsen anxiety initially | | Clomipramine (TCA) | Second-line | Potent serotonergic, FDA-approved | Anticholinergic effects, cardiac toxicity, slower titration | **Tip:** Clomipramine is reserved for SSRI non-responders or severe cases, as it requires slower titration and has more side effects. ## Expected Timeline 1. **Weeks 1–2:** Initiate sertraline 50 mg daily; patient may experience mild anxiety or GI upset 2. **Weeks 2–4:** Titrate to 100 mg daily 3. **Weeks 4–6:** Titrate to 150–200 mg daily (therapeutic dose for OCD) 4. **Weeks 6–12:** Assess response; if inadequate, consider increasing to 200 mg or switching agent **Key Point:** Response to SSRIs in OCD typically requires 8–12 weeks at therapeutic dose, longer than for depression (4–6 weeks). ## Adjunctive Management - **Cognitive-Behavioral Therapy (CBT) with Exposure and Response Prevention (ERP):** Gold standard; should be initiated concurrently with pharmacotherapy - **Augmentation strategies (if inadequate response):** Low-dose antipsychotics (risperidone, aripiprazole) added to SSRI [cite:Harrison 21e Ch 385]