Marie-Michelle Tremblay1,2, Sarah-Maude Rioux1,2, Charlie Fraser1,2, Geneviève Picher3, Chantal Mérette1,3, Anne-Pierre Bouffard1,2, Sophie L'heureux1,2, Marie-France Demers2,3,4, Marc-André Roy1,2,3; 1Département de Psychiatrie et Neurosciences, Faculté de Médecine, Université Laval, Québec, PQ, Canada, 2CNDV/IUSMQ/CIUSSS-CN, Québec, PQ, Canada, 3Centre de recherche CERVO, Québec, PQ, Canada, 4Faculté de Pharmacie, Université Laval, Québec, Canada
Recommendation on long-acting injectable (LAI) aripiprazole dosage based on phase II and phase III are that a 400mg dosage would be appropriate in 90% of patients and 300mg in 10%. Since these trials were performed in patients aged around 40, it is not known if they apply to first-episode psychosis (FEP). We are systematically reviewing extensive medical charts of all 61 patients from our FEP program who have been exposed to LAI Aripiprazole (average exposure: 15 months) and followed intensively by an inter-disciplinary team. Two trained psychiatry residents independently performed monthly ratings of efficacy (CGI-S) and tolerability (CGI-CB side effects subscale) and disagreements were reviewed to reach consensus and dosage was recorded. LAI dosage used was generally based on the following rules: patients were first stabilized on oral Aripiprazole to assess an optimal dosage; based on the latter, the first injection was either 400 or 300mg; the LAI dosage targeted at equilibrium was approximately 1mg oral for 20mg LAI and was adjusted based on response. 47.5% of patients were stabilized (CGI-S≤3; CGI-CB subscale ≤2 for ≥6 months) at dosages <300mg and 14.8% at dosages ≤200mg. 14/49 patients who received ≤300mg at some stage required lower dosage due to side effects. These preliminary results of our ongoing study suggest that it may be appropriate and/or needed to use LAI Aripiprazole dosage below 300mg in a significant proportion of FEP patients; hence, close monitoring of severity and tolerability may be required to “fine tune” LAI Aripiprazole dosage.
