In recent years, trials have been conducted in OCD patients with a newer generation of antidepressant drugs that are both potent and selective blockers of serotonin reuptake, i.e., fluvoxamine, paroxetine, sertraline and fluoxetine. Unlike clomipramine, none of these medications loses its selectivity for blocking serotonin reuptake in the body. Also in contrast to clomipramine (and other tricyclics), these drugs lack significant affinity for brain receptors that are thought to be responsible for undesirable side effects. In other words, the selective SRIs are “cleaner” drugs compared to clomipramine. All potent SRIs tested to date have proven effective in treating OCD. The effectiveness of fluvoxamine has been confirmed in children. Selective SRIs are generally well-tolerated. The most common side effects are nausea, drowsiness, insomnia, tremor and sexual dysfunction (problems with orgasm). There are few significant safety concerns and the risk with overdose is small.
SRIs take time to work. Daily treatment for eight to 12 weeks may be required before the symptoms of OCD begin to recede. Once improvement occurs, the medication is usually continued for at least another six to 12 months. Some patients can be successfully tapered off medication, but the majority seem to relapse after complete discontinuation of medication. Adding behavior therapy may reduce the rate of relapse following discontinuance of medication. Nearly two-thirds of patients with OCD experience significant symptom relief on SRIs. Among those that do improve, the degree of change is meaningful, but it is rarely complete. A person with OCD who has had a good response to an SRI might report that the time occupied by obsessions and compulsion is cut from six to two hours a day. This may allow the individual to return to work or school and resume a relatively normal and fulfilling life. Interestingly, how long someone has had OCD does not predict how well they will respond to SRI treatment. Marked improvement can be observed even after 35 years of continuous obsessive-compulsive symptoms.
SRIs are not without side effects. Nausea, tremors, diarrhea, insomnia and daytime drowsiness are some of the common side effects of the SRIs. Clomipramine may produce additional unpleasant symptoms, including dry mouth, constipation and weight gain. It also has risks associated with it, including possible adverse affects on heart rhythm, seizures and death with overdose. Some patients will tolerate one SRI better than another, but for the most part the selective SRIs listed above are better tolerated than clomipramine. With help from their doctor, most patients can find a dosage of medication that relieves symptoms while keeping side effects to a tolerable level.