Acetyl-L-Carnitine Augmentation of Clozapine in Partial-Responder Schizophrenia: A 12-Week, Open-Label Uncontrolled Preliminary Study

Objectives: This was the first 12-week, open-label, uncontrolled trial aimed at exploring the efficacy of acetyl-L-carnitine (ALC) add-on pharmacotherapy on clinical symptoms and cognitive functioning in 15 schizophrenia patients with suboptimal clinical response despite receiving clozapine (CLZ) monotherapy at the highest tolerated dosage. Methods: After clinical (Positive and Negative Symptoms Scale [PANSS]) and neuropsychological (Wisconsin Card Sorting Test, Stroop Color-Word Test, Verbal Fluency Test) assessments, patients received 1 g/d of ALC for 12 weeks. Results: A final sample of 9 subjects completed the study. Acetyl-L-carnitine augmentation of CLZ significantly reduced only PANSS domains "positive" (P = 0.049); at end point, only 2 subjects (22.2% of the completers) reached a minimal improvement (25% reduction in PANSS total score). No significant differences emerged in cognitive performances at the end of the study; effect sizes were small in each explored cognitive dimension. Conclusions: The findings provide preliminary evidence that ALC added to ongoing CLZ treatment appeared to be ineffective to improve symptoms in schizophrenia patientswho have failed to respond sufficiently to CLZ. Further trials with adequately powered methodology are needed to identify which augmentation strategies are more effective in schizophrenia patients showing a suboptimal response to CLZ.