A 35-year-old man with severe OCD has been on fluoxetine 80 mg daily for 14 weeks with only partial response (30% symptom reduction). His obsessions about harm and checking compulsions remain disabling. Which is the preferred next step in pharmacological management?

Explanation

## Management of SSRI-Refractory OCD **Key Point:** When an SSRI at therapeutic dose for ≥10–12 weeks yields inadequate response (<25% symptom reduction), **augmentation with a low-dose atypical antipsychotic** is the preferred next step, not dose escalation or switching. ### Rationale for Augmentation Strategy 1. **Evidence base:** Augmentation with risperidone, aripiprazole, or quetiapine improves response rates by 20–30% in SSRI-refractory OCD 2. **Mechanism:** Dopamine blockade in mesolimbic and mesocortical circuits enhances serotonergic effects 3. **Timing:** Typically added after 8–12 weeks of adequate SSRI dosing without sufficient response 4. **Dose:** Low-dose antipsychotics (risperidone 0.5–2 mg/day; aripiprazole 5–15 mg/day) minimize metabolic and motor side effects **High-Yield:** Augmentation is superior to switching SSRIs or further dose escalation in SSRI-partial responders. ### Augmentation Agents for OCD | Agent | Typical Augmentation Dose | Efficacy | Advantages | Disadvantages | |-------|---------------------------|----------|-----------|----------------| | Risperidone | 0.5–2 mg/day | 40–60% response | Good evidence, rapid onset | Weight gain, prolactin elevation | | Aripiprazole | 5–15 mg/day | 40–60% response | Lower metabolic risk, dopamine partial agonist | Akathisia, insomnia | | Quetiapine | 50–300 mg/day | 30–50% response | Sedating (useful if anxiety), fewer EPS | Weight gain, metabolic syndrome | **Clinical Pearl:** Aripiprazole may be preferred in patients with metabolic risk factors (obesity, diabetes) due to lower weight gain potential compared to risperidone or quetiapine. ### Decision Algorithm for SSRI-Partial Response ```mermaid flowchart TD A[SSRI at therapeutic dose for 10-12 weeks]:::outcome --> B{Adequate response?}:::decision B -->|Yes| C[Continue SSRI + CBT/ERP]:::action B -->|No| D{Adequate trial duration?}:::decision D -->|No| E[Extend to 14-16 weeks]:::action D -->|Yes| F[Partial response or non-response]:::outcome F --> G{Preferred next step?}:::decision G -->|Augmentation| H[Add low-dose atypical antipsychotic]:::action G -->|Alternative| I[Switch to clomipramine or different SSRI]:::action H --> J[Risperidone 0.5-2 mg or Aripiprazole 5-15 mg]:::action J --> K[Reassess at 4-6 weeks]:::decision ``` **Mnemonic:** **RAQ** = Risperidone, Aripiprazole, Quetiapine are the preferred augmentation agents for SSRI-refractory OCD.