BLOOD LEVELS OF TREATMENT RESISTANT OBSESSIVE-COMPULSIVE DISORDER PATIENTS PRESCRIBED SUPRA-NORMAL DOSAGES OF SERTRALINE

Abstract

. Aims This study examined the blood levels of Sertraline in patients with profound, refractory Obsessive-Compulsive Disorder (OCD) and who were prescribed dosages in excess of recommended limits. Background Studies in patients with OCD have demonstrated that higher levels of serotonin reuptake inhibiting (SRI) drugs are usually needed to obtain remission that those required for depression. This observation led some workers to suggest that supra-normal doses of selective SRIs may prove beneficial in treatment refractory patients. Pampaloni et al. (2010) found that these high doses of selective SRIs were well tolerated in treatment refractory patients and led to clinical improvement. The aim of this study was to examine the blood levels of patients prescribed supra-normal doses of Sertraline. If the blood levels remained within therapeutic range, then this would suggest that these patients either have reduced absorption of the drug or were rapidly metabolising Sertraline. Methods Patients selected for the study had all been admitted to the National Inpatient Service for OCD/BDD based in South West London and St George’s NHS Trust. This Unit has been described elsewhere (Drummond et al., 2012). Owing to the wards admission criteria, all the patients had previously received at least two trials of different SSRIs or Clomipramine for a minimum of 3 months each without any resolution of symptoms. In addition, all patients had received augmentation with a dopamine blocker and also at least 2 trials of Exposure and response-prevention psychological therapy. Despite these treatments, all patients were admitted to the service with a Yale-Brown Obsessive Compulsive Score within the high end of the “profoundly ill” range (>35/40). Successively admitted patients who were prescribed Sertraline in doses greater than the recommended 200mg per day were included in the study. These patients who were initially unresponsive to 200mg Sertraline had their daily doses titrated upwards in 50mg increases every 2-4 weeks up to a maximum of 400mg (depending on efficacy and any side effects). Blood samples were taken shortly after their morning dose had been administered. This was after the patients had stabilised for at least 2 weeks on the higher doses. Results 7 patients were included in the study. Blood levels of Sertraline were found to be in therapeutic range for all patients. In general, the blood levels remained within the lower half of normal reference range despite being prescribed supra-normal Sertraline dosages ranging from 250mg to 400mg per day. Conclusion This study demonstrates that some patients who are refractory to standard doses have blood levels within the therapeutic range. This finding suggests that these patients either absorb the drug poorly or metabolise it rapidly.