Outcomes
- There was a statistically significant difference in Y-BOCS score in patients treated with memantine at Week 8 and Week 12 vs those who received placebo. By Week 8, 17.2% of patients in the memantine group showed a decrease in Y-BOCS score, compared with -0.8% patients in the placebo group. The difference became more significant by Week 12, with 40.9% in the memantine group showing a decrease in Y-BOCS score vs -0.3% in the placebo group. This resulted in 73.3% of patients achieving treatment response.
- Eight weeks of memantine augmentation was necessary to observe a significant improvement in OCD symptoms, and 12 weeks was needed for treatment response.
- The mean Y-BOCS total score decreased significantly in the memantine group from Week 4 to Week 8 (16.8%) and again from Week 8 to Week 12 (28.5%).
- The memantine group showed good tolerability and safety. There were no clinically significant adverse effects.
Conclusion
- Memantine augmentation in patients with severe OCD who do not respond to an SRI is effective and well-tolerated.
4. Shalbafan M, Malekpour F, Tadayon Najafabadi B, et al. Fluvoxamine combination therapy with tropisetron for obsessive-compulsive disorder patients: a placebo-controlled, randomized clinical trial. J Psychopharmacol. 2019;33(11):1407- 1414. doi:10.1177/0269881119878177
Studies have demonstrated the involvement of the amygdala, medial and lateral orbitofrontal cortex, and dorsal anterior cingulate cortex in OCD. Additionally, studies have also investigated the role of serotonin, dopamine, and glutamate system dysregulation in the pathology of OCD.
The 5-HT3 receptors are ligand-gated ion channels found in the prefrontal cortex, amygdala, and hippocampus. Studies of 5-HT3 receptor antagonists such as ondansetron and granisetron have shown beneficial results in augmentation with SSRIs for patients with OCD.11 Tropisetron, a 5-HT3 receptor antagonist, is highly lipophilic and able to cross the blood brain barrier. It also has dopamine-inhibiting properties that could have benefits in OCD management. Shalbafan et al13 evaluated the efficacy of tropisetron augmentation to fluvoxamine for patients with OCD.
Study design
- In a 10-week, randomized, double-blind, placebo-controlled, parallel-group trial, 108 individuals age 18 to 60 who met DSM-5 criteria for OCD and had a Y-BOCS score >21 received fluvoxamine plus tropisetron or fluvoxamine plus placebo. A total of 48 (44.4%) participants in each group completed the trial. Participants were evaluated using the Y-BOCS scale at baseline and at Week 4 and Week 10.
- The primary outcome was decrease in total Y-BOCS score from baseline to Week 10. The secondary outcome was the difference in change in Y-BOCS obsession and compulsion subscale scores between the groups.
Outcomes
- The Y-BOCS total score was not significantly different between the 2 groups (P = .975). Repeated measures analysis of variance determined a significant effect for time in both tropisetron and placebo groups (Greenhouse-Geisser F [2.72–2303.84] = 152.25, P < .001; and Greenhouse-Geisser F [1.37–1736.81] = 75.57, P < .001, respectively). At Week 10, 35 participants in the tropisetron group and 19 participants in the placebo group were complete responders.
- The baseline Y-BOCS obsession and compulsion subscales did not significantly differ between treatment groups.
Conclusion
- Compared with participants in the placebo group, those in the tropisetron group experienced a significantly greater reduction in OCD symptoms as measured by Y-BOCS score. More participants in the tropisetron group experienced complete response and remission.
- This study demonstrated that compared with placebo, when administered as augmentation with fluvoxamine, tropisetron can have beneficial effects for patients with OCD.
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