Psychiatry · Clinical trials
Obsessive-Compulsive Disorder (OCD) Clinical Trials
Approved therapies, the pivotal-trial endpoints they were judged on, the magnitude of benefit — and the drugs that failed their endpoints, and why.
Indication overview
About obsessive-compulsive disorder (ocd) — and why its trials are hard
Obsessive-Compulsive Disorder is a chronic anxiety-spectrum condition defined by intrusive, distressing obsessions and repetitive compulsions performed to reduce anxiety. Unlike PTSD, OCD has an established, well-replicated pharmacologic evidence base: the tricyclic clomipramine and multiple SSRIs are FDA-approved, all acting on serotonergic transmission and typically requiring higher doses and longer trials (10-12 weeks) than in depression. The Yale-Brown Obsessive Compulsive Scale (Y-BOCS) is the universal primary endpoint. Clomipramine (1989) was first, followed by fluoxetine, fluvoxamine, paroxetine, and sertraline in the 1990s. Effect sizes are moderate, response is often partial, and 40-60% of patients have residual symptoms, driving interest in augmentation strategies (antipsychotics, glutamatergic agents) and neuromodulation (deep brain stimulation, TMS). Serotonin reuptake inhibition combined with exposure-and-response-prevention CBT remains the standard of care. Several augmentation candidates, particularly glutamate-modulating and 5-HT3 agents, have failed to consistently outperform placebo, keeping the approved medication list essentially unchanged for decades.
Approved therapies & pivotal evidence
What's been approved — and by how much it moved the endpoint
| Drug (brand) | Approved | Setting | Pivotal trial | Primary endpoint | Magnitude of benefit |
|---|---|---|---|---|---|
| Clomipramine (Anafranil) | 1989 | Adults and children (>=10 yrs) with OCD; tricyclic serotonin reuptake inhibitor | Multicenter placebo-controlled trials (DeVeaugh-Geiss et al. 1991) | Y-BOCS total score change from baseline | Approximately 38-44% mean Y-BOCS reduction vs ~3-5% placebo; among the largest SRI effect sizes in OCD (unverified exact figures) |
| Fluoxetine (Prozac) | 1994 | Adults and pediatric OCD; SSRI, often at higher doses (up to 60-80 mg) | Fixed-dose placebo-controlled trials (Tollefson et al. 1994) | Y-BOCS total score change from baseline | Significant dose-related Y-BOCS reduction vs placebo (~25-35%) (unverified exact figures) |
| Fluvoxamine (Luvox) | 1994 | Adults and pediatric OCD; SSRI | Multicenter placebo-controlled trials (Goodman et al.) | Y-BOCS total score change from baseline | Significant Y-BOCS improvement vs placebo; moderate effect size (unverified exact figures) |
| Paroxetine (Paxil) | 1996 | Adults with OCD; SSRI | Fixed-dose placebo-controlled trial (Hollander et al.; Zohar & Judge 1996) | Y-BOCS total score change from baseline | Significant Y-BOCS reduction at 40-60 mg vs placebo; effective doses higher than 20 mg (unverified exact figures) |
| Sertraline (Zoloft) | 1997 | Adults and pediatric OCD; SSRI | Placebo-controlled trials (Greist et al. 1995) | Y-BOCS total score change from baseline | Significant Y-BOCS reduction vs placebo; moderate effect size (unverified exact figures) |
Where trials have failed
Drugs that missed their endpoint — and what contributed
The most instructive lessons in obsessive-compulsive disorder (ocd) development come from programmes that failed the endpoint that mattered.
| Drug / trial | Endpoint outcome | What contributed |
|---|---|---|
| D-cycloserine (CBT augmentation) — Randomized placebo-controlled augmentation of exposure-based CBT, including pediatric OCD trials | Did not produce significant benefit over placebo when augmenting CBT; overall ineffective as a broad augmentation strategy | Inconsistent timing of dosing relative to exposure sessions, small effects, and failure to replicate early positive signals |
| Ondansetron (SRI augmentation) — 5-HT3 antagonist augmentation trials of fluvoxamine/SRIs (e.g., 8-week augmentation studies) | Mixed to negative results; meta-analyses show inconsistent, at best marginal Y-BOCS benefit and no FDA approval | Small samples, heterogeneous designs, and lack of robust, replicated separation from placebo |
Choosing the right endpoint
Primary endpoints that matter in obsessive-compulsive disorder (ocd) trials
- Y-BOCS (Yale-Brown Obsessive Compulsive Scale) — 10-item clinician scale (0-40); the universal primary endpoint measuring obsession and compulsion severity
- CY-BOCS — Children's version of Y-BOCS used in pediatric OCD registration trials
- CGI-I / CGI-S — Global impression of improvement and severity; standard responder co-measures
- Y-BOCS responder rate (>=25-35% reduction) — Categorical responder definition frequently used as secondary endpoint
How iNGENū runs obsessive-compulsive disorder (ocd) trials
Physician-led design, built for FDA submission
Endpoint & biomarker strategy
Board-certified specialists design endpoints and patient selection aligned to current FDA guidance for this indication.
FDA-ready data
Built to ICH-GCP and 21 CFR 312.120, with direct FDA submission — data accepted by the FDA, EMA and MHRA.
Faster, lower-cost delivery
~4-week ethics via the TGA CTN scheme, up to 43.5% R&D rebate, and 80–90% below US CRO cost.
Request a fixed-milestone proposal and a tailored endpoint & feasibility summary for this indication.
Frequently asked questions
Obsessive-Compulsive Disorder (OCD) clinical trials — FAQs
Which medications are FDA-approved for OCD?
What endpoint do OCD trials use?
Why do so many OCD augmentation drugs fail?
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