Schizophrenia is a prevalent psychiatric illness, which causes significant financial and social burden on the population overall. The development of second generation antipsychotics, such as Aripiprazole, Risperidone, and Paliperidone, has changed treatment practice for many psychiatrists. Aripiprazole has extremely high binding affinity for the dopamine D2 receptor, which is the receptor thought to be responsible for the antipsychotic effect, although Aripiprazole is not the most potent of the second generation antipsychotics. In theory, Aripiprazole could displace or outcompete other, more potent antipsychotics, prompting decreased antipsychotic effect. We describe a proposed case of this phenomenon, Ms. A. We describe how Aripiprazole may have caused a worsening of psychiatric symptoms by blocking the antipsychotic effects of Paliperidone due to its strong binding affinity for the D2 receptor. Aripiprazole has a high affinity for the D2 receptor, but may have a lesser reduction of psychotic symptoms compared to other antipsychotics. Prescribers should be aware of this potential interaction and carefully consider initiating long-acting injectable forms of Aripiprazole to avoid this phenomenon. Int Clin

Several studies have shown an association between Systemic Lupus Erythematosus (SLE) and the Epstein Barr Virus (EBV). Our laboratory recently demonstrated that BALB/c mice injected with the major EBV nuclear antigen, EBNA-1, developed antibodies to EBNA-1 that cross-react with double stranded DNA (dsDNA). We generated monoclonal antibodies (MAbs) to EBNA-1 from EBNA-1 injected mice and demonstrated by anti-dsDNA ELISA, dsDNA affinity columns, and Crithidia luciliae assays, that these antibodies cross-react with dsDNA. Studies are underway to determine the pathogenicity of these MAbs. We have been mapping the epitope in EBNA-1 that serves as a peptide mimotope for dsDNA. We now demonstrate that the mimotope is contained within the carboxyl region of the EBNA-1 protein, between amino acids 459 and 607. This region contains well-defined secondary structure, which suggests that the basis for the cross-reactivity with dsDNA could be due to a conformational epitope in EBNA-1. Studies are in progress to further map this cross-reactive epitope. Identification of this epitope may help in designing diagnostic and therapeutic strategies that can mask the epitope from the immune system following EBV infection and thereby prevent the development of antibodies that cross-react with dsDNA.

BackgroundAripiprazole has high binding affinity for the dopamine D2 receptor, which is thought to be responsible for the antipsychotic effect, though aripiprazole is not the most potent of the second-generation antipsychotics. Theoretically, aripiprazole could displace or outcompete more potent antipsychotics, prompting decreased antipsychotic effect. We describe a case of aripiprazole potentially worsening psychiatric symptoms by blocking paliperidone.CaseMs. A is a 43-year-old woman with schizophrenia, multiple inpatient hospitalizations, and a history of court-ordered treatment. She historically has had good response to oral and long-acting formulations of risperidone and paliperidone. Ms. A requested a medication change and was transitioned to aripiprazole lauroxil injection with plan for bimonthly administration. Approximately 1 month after receiving her aripiprazole lauroxil injection, Ms. A presented to our CPEP due to symptoms of psychosis and was admitted to our inpatient unit. She was restarted on oral paliperidone, titrated up to her previously effective dose, and was transitioned to paliperidone palmitate LAI. In contrast to prior admissions, she did not respond well to paliperidone and displayed continued and worsened psychosis.DiscussionPrior studies have examined how adding aripiprazole to another, more potent D2 antagonist can cause a relapse in psychotic symptoms; however, few studies have investigated the inverse relationship or mechanism. Those that have proposed mechanisms typically refer to aripiprazole’s partial agonist activity as the causative factor, rather than an impediment to antipsychotic binding which we have described. Prescribers should be aware of this potential interaction and carefully consider initiating long-acting injectable forms of aripiprazole to avoid this phenomenon.FundingNo Funding