No abstract

New psychotropic drugs introduced in clinical practice in recent years include new antidepressants, such as selective serotonin reuptake inhibitors (SSRI) and 'third generation' antidepressants, and atypical antipsychotics, i.e. clozapine, risperidone, olanzapine, quetiapine, ziprasidone and amisulpride. These agents are extensively metabolized in the liver by cytochrome P450 (CYP) enzymes and are therefore susceptible to metabolically based drug interactions with other psychotropic medications or with compounds used for the treatment of concomitant somatic illnesses. New antidepressants differ in their potential for metabolic drug interactions. Fluoxetine and paroxetine are potent inhibitors of CYP2D6, fluvoxamine markedly inhibits CYP1A2 and CYP2C19, while nefazodone is a potent inhibitor of CYP3A4. These antidepressants may be involved in clinically significant interactions when coadministered with substrates of these isoforms, especially those with a narrow therapeutic index. Other new antidepressants including sertraline, citalopram, venlafaxine, mirtazapine and reboxetine are weak in vitro inhibitors of the different CYP isoforms and appear to have less propensity for important metabolic interactions. The new atypical antipsychotics do not affect significantly the activity of CYP isoenzymes and are not expected to impair the elimination of other medications. Conversely, coadministration of inhibitors or inducers of the CYP isoenzymes involved in metabolism of the various antipsychotic compounds may alter their plasma concentrations, possibly leading to clinically significant effects. The potential for metabolically based drug interactions of any new psychotropic agent may be anticipated on the basis of knowledge about the CYP enzymes responsible for its metabolism and about its effect on the activity of these enzymes. This information is essential for rational prescribing and may guide selection of an appropriate compound which is less likely to interact with already taken medication(s).

No abstract

The present 16-week double-blind, randomized, placebo-controlled trial had the aim to explore the efficacy of lamotrigine add-on pharmacotherapy on clinical symptomatology and cognitive functioning in a sample of patients with treatment-resistant obsessive-compulsive disorder (OCD) receiving serotonin reuptake inhibitors (SRIs). After clinical and neurocognitive assessments, patients were randomly allocated to receive, in a double-blind design, 100 mg/day of lamotrigine or a placebo. A final sample of 33 patients completed the study. The results obtained indicate that lamotrigine added to stable SRI treatment substantially improved obsessive-compulsive (Yale-Brown Obsessive Compulsive Scale: obsessions, p < 0.0001; compulsions, p < 0.0001; total score, p < 0.0001), and affective symptoms (Hamilton Rating Scale for Depression p < 0.0001). Regarding cognitive functions, improvement was observed only in Semantic Fluency (p = 0.004). The findings provide evidence that lamotrigine augmentation of SRI treatment is well tolerated and may be proposed as an effective therapeutic strategy to improve outcome in treatment-resistant OCD.