{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,8]],"date-time":"2026-10-08T17:03:12Z","timestamp":1791478992439,"version":"4.3.4"},"reference-count":15,"publisher":"Wiley","issue":"3","license":[{"start":{"date-parts":[[2025,1,21]],"date-time":"2025-01-21T00:00:00Z","timestamp":1737417600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["accpjournals.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Pharmacotherapy"],"published-print":{"date-parts":[[2025,3]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Introduction<\/jats:title><jats:p>Clozapine and risperidone are second\u2010generation antipsychotics used in the treatment of schizophrenia. There are no guidelines on cross\u2010titration of antipsychotics and, additionally, there is a paucity of published data to support the potential utility of using serum drug levels to guide dosing in these situations.<\/jats:p><\/jats:sec><jats:sec><jats:title>Case Report<\/jats:title><jats:p>A 68\u2010year\u2010old female patient with a history of schizophrenia, taking risperidone and fluoxetine, and a recent diagnosis of Parkinson's disease was admitted to the hospital after a fall at home. During the patient's hospital stay, utilizing serum clozapine levels as guidance, the patient was cross\u2010titrated from risperidone 12\u2009mg daily to a final dose of clozapine 75\u2009mg daily over the span of 17\u2009days, in the setting of multiple possible drug\u2013drug interactions.<\/jats:p><\/jats:sec><jats:sec><jats:title>Discussion<\/jats:title><jats:p>There is no evidence\u2010based guidance on transitioning patients from one antipsychotic to another especially in the setting of drug\u2013drug interactions. In this case, the patient was successfully transitioned from risperidone to clozapine using serum clozapine levels and clinical status to guide decision\u2010making.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>Utilizing serum clozapine levels may be helpful in guiding dose changes during antipsychotic cross\u2010titration, especially when multiple drug interactions are involved.<\/jats:p><\/jats:sec>","DOI":"10.1002\/phar.4649","type":"journal-article","created":{"date-parts":[[2025,1,21]],"date-time":"2025-01-21T07:01:57Z","timestamp":1737442917000},"page":"187-190","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Cross\u2010titration from risperidone to clozapine utilizing clozapine serum concentrations: A case 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USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9035-5953","authenticated-orcid":false,"given":"Stephanie","family":"Nichols","sequence":"additional","affiliation":[{"name":"Department of Pharmacy Practice, School of Pharmacy, Westbrook College of Health Professions University of New England  Portland Maine USA"},{"name":"Department of Psychiatry, School of Medicine Tufts University  Boston Massachusetts USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2025,1,21]]},"reference":[{"key":"e_1_2_8_2_1","volume-title":"East Hanover","author":"Clozaril\u00ae [package 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