Open Access

Marte Z. van der Horst, Yoeki Meijer, Nini de Boer, Sinan Guloksuz, Alkomiet Hasan, Dan Siskind, Elias Wagner, Cynthia Okhuijsen-Pfeifer, Jurjen J. Luykx, Ahmet Müderrisoğlu, Alba Toll Privat, Alde Bouhuis, Amy Jongkind, Ana Gonzalez-Pinto, Anna Mane Santacana, Armando D'Agostino, Aygün Ertugrul, Ayşe Elif Anil Yağcioğlu, Benedicto Crespo-Facorro, Bianca Sanchez-Barbero, Carlos Spuch, Carla Lou Morgenroth, Carmen Fernandez de Pinedo, Cecilia Casetta, Chad Bousman, Christos Pantelis, Claudia Ovejas-Catalán, Clemente Garcia-Rizo, Cynthia Okhuijsen-Pfeifer, Dan Cohen, Dragana Ignjatovic Ristic, Edwin Beld, Eila Repo-Tiihonen, Ellen Jeger-Land, Elisabet Vilella, Erwin Bekema, Stevan Sepúlveda, Federico Seghi, Federico Wiedenmann, Francesca Martini, Francesca Serio, Francesca Vairano, Giacomo Mercuriali, Giovanni Boido, Gökhan Yoca, Hanneke van Beek, Harm Gijsman, Heli Tuppurainen, Ian Everall, Ivona Novakovic, Inaki Zorrilla, Ibrahim Mert Erdoğan, Jacopo Sapienza, Jan Bogers, Jari Tiihonen, Javier Vázquez-Bourgon, Jim van Os, Johannes Schneider-Thoma, Jurjen Luykx, Koen Grootens, Lorea Mar-Barrutia, Lourdes Martorell, Maarten Bak, Marco Spangaro, Marije de Vos, Mariken de Koning, Marina Garriga, Markku Lähteenvuo, Marta Bosia, Marte van der Horst, Melih Önder Babaoğlu, Mike Veereschild, Mirko Manchia, Monika Edlinger, Paloma Fuentes-Pérez, Pasquale Paribello, Purificacion Lopez-Pena, René Kahn, Roberto Cavallaro, Selene Veerman, Stefan Gutwinski, Stefanie Schreiter, Stephan Ripke, Tania Rivera Baltanás, Tatiana Oviedo-Salcedo, Tero Hallikainen, Thomas Görlitz, Wouter Alink, Yavuz Ayhan

• Clozapine is often underused due to concerns about adverse drug reactions (ADRs) but studies into their prevalences are inconclusive. We therefore comprehensively examined prevalences of clozapineassociated ADRs in individuals with schizophrenia and demographic and clinical factors associated with their occurrence. Data from a multi-center study (n=698 participants) were collected. The mean number of ADRs during clozapine treatment was 4.8, with 2.4% of participants reporting no ADRs. The most common ADRs were hypersalivation (74.6%), weight gain (69.3%), and increased sleep necessity (65.9%), all of which were more common in younger participants. Participants with lower BMI prior to treatment were more likely to experience significant weight gain (>10%). Constipation occurred more frequently with higher clozapine blood levels and doses. There were no differences in ADR prevalence rates between participants receiving clozapine monotherapy and polytherapy. These findings emphasize theClozapine is often underused due to concerns about adverse drug reactions (ADRs) but studies into their prevalences are inconclusive. We therefore comprehensively examined prevalences of clozapineassociated ADRs in individuals with schizophrenia and demographic and clinical factors associated with their occurrence. Data from a multi-center study (n=698 participants) were collected. The mean number of ADRs during clozapine treatment was 4.8, with 2.4% of participants reporting no ADRs. The most common ADRs were hypersalivation (74.6%), weight gain (69.3%), and increased sleep necessity (65.9%), all of which were more common in younger participants. Participants with lower BMI prior to treatment were more likely to experience significant weight gain (>10%). Constipation occurred more frequently with higher clozapine blood levels and doses. There were no differences in ADR prevalence rates between participants receiving clozapine monotherapy and polytherapy. These findings emphasize the high prevalence of clozapine-associated ADRs and highlight several demographic and clinical factors contributing to their occurrence. By understanding these factors, clinicians can better anticipate and manage clozapine-associated ADRs, leading to improved treatment outcomes and patient well-being.…