Myoclonus as a Single Side Effect of Combination of Selective Serotonin Reuptake Inhibitors (SSRIs) and Clomipramine: Three Case Reports

Selective Serotonin Reuptake Inhibitors (SSRIs) are the most popular psychiatric medications that are approved for several neuropsychiatric conditions such as depression and obsessive-compulsive disorder (OCD). On the other hand, clomipramine is a tricyclic anti-depressant which is the only approved medication, among this class, to treat OCD due to its substantial effects on serotonergic system. Combination of SSRIs and clomipramine is uncommon in routine psychiatric practice because it can increase the risk of serotonin syndrome which is characterized by myoclonus, headache, nausea, confusion, diarrhea, tremor, twitching muscles, and agitation. However, it could be useful in patients suffering from treatment-resistant OCD.Here, we describe three cases of OCD patients, treated by combination of SSRIs and clomipramine who showed only myoclonic movements in initial week without any other manifestations of the serotonin syndrome. In less than one week after initiation of medication, abnormal movements disappeared, and in six month follow-up evaluation, the patients were observed with considerable improvements. Indeed, myoclonic movements is not a predictor of full-blown serotonin syndrome when combination of SSRIs and clomipramine is used. Therefore, the combination could be a considerable approach in treatment of refractory OCD.