A 28-year-old woman presents with intrusive thoughts about harming her children, accompanied by compulsive checking and reassurance-seeking behaviors. She has had symptoms for 18 months and reports significant functional impairment. What is the drug of choice for first-line pharmacotherapy of her obsessive-compulsive disorder?

Explanation

## First-Line Pharmacotherapy in OCD **Key Point:** SSRIs are the first-line pharmacological agents for OCD, with sertraline, fluoxetine, paroxetine, and fluvoxamine being FDA-approved options. Sertraline is commonly preferred due to favorable tolerability and efficacy profile. ### Mechanism of Action SSRIs inhibit serotonin reuptake, increasing synaptic serotonin availability. OCD is thought to involve dysregulation of the orbitofrontal-anterior cingulate-striatal circuit, and serotonergic enhancement helps normalize this pathway. ### Dosing and Response Timeline - **Initial dose:** 50 mg daily (sertraline) - **Therapeutic dose range:** 50–200 mg daily - **Time to response:** 8–12 weeks (longer than in depression; some sources cite up to 12 weeks) - **Dose escalation:** Increase by 50 mg every 1–2 weeks if tolerated and no response ### Efficacy Comparison | Agent | Efficacy | Tolerability | First-Line Status | |-------|----------|--------------|-------------------| | Sertraline | High | Excellent | Yes | | Fluoxetine | High | Good | Yes | | Paroxetine | High | Moderate | Yes | | Fluvoxamine | High | Moderate | Yes | | Clomipramine | Very High | Moderate (TCA side effects) | Second-line | **High-Yield:** Clomipramine, a tricyclic antidepressant with potent serotonergic activity, is highly effective in OCD but is reserved for second-line use due to anticholinergic side effects, orthostatic hypotension, and cardiac conduction risks. ### Clinical Pearl SSRIs often require higher doses and longer treatment duration in OCD compared to depression. Partial response at 8 weeks warrants continuation to 12 weeks before considering augmentation or switching. ### Augmentation Strategies (if inadequate response) - Atypical antipsychotics (risperidone, aripiprazole) added to SSRI - Clomipramine added to SSRI (though evidence is mixed) **Warning:** Do not confuse OCD pharmacotherapy with anxiety disorder treatment — anxiolytics (benzodiazepines, buspirone) alone are ineffective in OCD and should not be used as monotherapy.