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de Leon J, Baldessarini RJ, Balon R, Bilbily J, Caroff SN, Citrome L, Correll CU, Cotes RO, Davis JM, DeLisi LE, Faden J, Freudenreich O, Goldsmith DR, Gurrera R, Josiassen RC, Kane JM, Kelly DL, Keshavan MS, Laitman RS, Lam YWF, Leung JG, Love RC, McCollum B, McGrane IR, Meyer J, Nasrallah HA, Nucifora FC, Rothschild AJ, Rubio JM, Sajatovic M, Sarpal DK, Schoretsanitis G, Shad M, Shelton C, Sher L, Singh B, Surya S, Zarzar TR, Sanz EJ, De las Cuevas C. Letter to the FDA Proposing Major Changes in the US Clozapine Package Insert Supported by Clozapine Experts Worldwide. Part I: A Review of the Pharmacokinetic Literature and Proposed Changes. J Clin Psychopharmacol 2025; 45:179-196. [PMID: 40198781 PMCID: PMC12105979 DOI: 10.1097/jcp.0000000000001987] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2024] [Accepted: 10/02/2024] [Indexed: 04/10/2025]
Abstract
PURPOSE/BACKGROUND Clozapine was approved in the United States (US) using 1989 regulations and knowledge. After 30 years, many sections of the US package insert (PI) are outdated. METHODS We comprehensively reviewed the literature to propose PI updates. We present the information in 2 articles. In Part I, we focus on basic pharmacology based on 407 relevant articles. Part II focuses on clinical aspects and pharmacovigilance. FINDINGS/RESULTS Based on more recent expectations of Food and Drug Administration regulations, we reviewed clozapine basic pharmacology including the following: 1) clearance, 2) pharmacokinetics and pharmacodynamics, and 3) monitoring tools. We identified 9 major problems in the basic pharmacological sections of the PI including the following: 1) in vivo studies indicate that clozapine is dependent on CYP1A2 for its metabolism, 2) the minor role of CYP2D6 in clozapine metabolism requires removing the PI recommendation to lower clozapine doses in CYP2D6 poor metabolizers, 3) in nontoxic concentrations CYP3A4 has a minor role in clozapine metabolism and potent CYP3A4 inhibitors lack clinically relevant effects, 4) several drug-drug interactions need to be updated based on recent literature, 5) systemic inflammation may decrease clozapine metabolism and increase the risk of clozapine intoxication, 6) obesity may decrease clozapine metabolism, 7) patients of Asian and Indigenous American ancestry need lower clozapine doses, 8) personalized titration and c-reactive protein monitoring should be considered until prospective studies are available, and 9) the half-life section needs to be modified to acknowledge that single dosing at night is frequent in the US. IMPLICATIONS/CONCLUSIONS An improvement in the US clozapine PI may lead to improvement in PIs worldwide.
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Affiliation(s)
- Jose de Leon
- From the Department of Psychiatry, University of Kentucky, Lexington, KY
- Mental Health Research Center, Eastern State Hospital, Lexington, KY
- Biomedical Research Centre in Mental Health Net (CIBERSAM), Santiago Apostol Hospital, University of the Basque Country, Vitoria, Spain
| | - Ross J. Baldessarini
- International Consortium for Mood & Psychotic Disorders Research, Mailman Research Center, McLean Hospital, Belmont, MA
- Department of Psychiatry, Harvard Medical School, Boston, MA
| | - Richard Balon
- Departments of Psychiatry and Behavioral Neurosciences and Anesthesiology, Wayne State University, Detroit, MI
| | - John Bilbily
- Department of Psychiatry, Washington University in St. Louis, St. Louis, MO
| | - Stanley N. Caroff
- Behavioral Health Service, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA
- Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA
| | - Leslie Citrome
- New York Medical College, Department of Psychiatry and Behavioral Sciences, Valhalla, NY
| | - Christoph U. Correll
- The Zucker Hillside Hospital, Psychiatry Research, Northwell Health, Glen Oaks, NY
- Department of Psychiatry, Zucker School of Medicine at Northwell/Hofstra, Hempstead, NY
- Department of Child and Adolescent Psychiatry, Charité Universitätsmedizin, Berlin, Germany
| | - Robert O. Cotes
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA
| | - John M. Davis
- Department of Psychiatry, University of Illinois at Chicago, Chicago, IL
| | - Lynn E. DeLisi
- Department of Psychiatry, Cambridge Health Alliance, Harvard Medical School, Cambridge, MA
| | - Justin Faden
- Department of Psychiatry, Lewis Katz School of Medicine at Temple University, Philadelphia, PA
| | - Oliver Freudenreich
- Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - David R. Goldsmith
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA
| | - Ronald Gurrera
- Department of Psychiatry, Harvard Medical School, Boston, MA
- Mental Health Service, VA Boston Healthcare System, Boston, MA
| | | | - John M. Kane
- The Zucker Hillside Hospital, Psychiatry Research, Northwell Health, Glen Oaks, NY
- Department of Psychiatry, Zucker School of Medicine at Northwell/Hofstra, Hempstead, NY
| | - Deanna L. Kelly
- Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, MD
| | | | | | - Y. W. Francis Lam
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX
| | | | - Raymond C. Love
- Department of Practice, Sciences, and Health Outcomes Research, University of Maryland School of Pharmacy, Baltimore, MD
| | | | - Ian R. McGrane
- Department of Pharmacy Practice, University of Montana, Missoula, MT
| | - Jonathan Meyer
- Department of Psychiatry, University of California, San Diego, CA
| | - Henry A. Nasrallah
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, OH
| | - Frederick C. Nucifora
- Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Anthony J. Rothschild
- Department of Psychiatry, University of Massachusetts Chan Medical School and UMass Memorial HealthCare, Worcester, MA
| | - Jose M. Rubio
- The Zucker Hillside Hospital, Psychiatry Research, Northwell Health, Glen Oaks, NY
- Department of Psychiatry, Zucker School of Medicine at Northwell/Hofstra, Hempstead, NY
| | - Martha Sajatovic
- Department of Psychiatry and of Neurology, Case Western Reserve University School of Medicine, University Hospitals Cleveland Medical Center, Cleveland, OH
| | - Deepak K. Sarpal
- Department of Psychiatry, School of Medicine, University of Pittsburgh, Pittsburgh, PA
| | - Georgios Schoretsanitis
- The Zucker Hillside Hospital, Psychiatry Research, Northwell Health, Glen Oaks, NY
- Department of Psychiatry, Zucker School of Medicine at Northwell/Hofstra, Hempstead, NY
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zürich, Zürich, Switzerland
| | - Mujeeb Shad
- Department of Psychiatry, University of Nevada, Las Vegas, NV
| | - Charles Shelton
- From the Department of Psychiatry, University of Kentucky, Lexington, KY
- Eastern State Hospital, Lexington, KY
| | - Leo Sher
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Balwinder Singh
- Department of Psychiatry and Psychology, Mayo Clinic, Rochester, MI
| | - Sandarsh Surya
- Department of Psychiatry and Health Behavior, Augusta University, Augusta, GA
| | - Theodore R. Zarzar
- Department of Psychiatry, University of North Carolina School of Medicine, Chapel Hill, NC
| | - Emilio J. Sanz
- Department of Physical Medicine and Pharmacology, School of Medicine, Universidad de La Laguna, Canary Islands, Spain
- Hospital Universitario de Canarias, Tenerife, Spain
| | - Carlos De las Cuevas
- Department of Internal Medicine, Dermatology and Psychiatry, School of Medicine, and Instituto Universitario de Neurociencia (IUNE), University of La Laguna, Canary Islands, Spain
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Mach A, Wnorowska A, Siwek M, Wojnar M, Radziwoń-Zaleska M. The effects of clinical and pharmacological factors on the ratio of clozapine to norclozapine in psychiatric patients. Front Pharmacol 2025; 15:1518739. [PMID: 39840091 PMCID: PMC11746079 DOI: 10.3389/fphar.2024.1518739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2024] [Accepted: 12/11/2024] [Indexed: 01/23/2025] Open
Abstract
Background Due to its exceptional effectiveness, clozapine (CLO), whose metabolite is norclozapine (NCLO), is a drug of choice in the management of treatment-resistant schizophrenia. The purpose of this study was to assess the factors modifying the CLO/NCLO ratio (CNR). Methods A total of 446 blood samples (233 of which were drawn from females and 213 from males, aged from 18 to 77 years) were analyzed in this study. The patients were treated at a psychiatric hospital in the period 2016-2021. Serum CLO and NCLO levels were determined with high-performance liquid chromatography coupled with a UV detector. Results The median CNR was 2.38 (minimum 0.30, maximum 14.36). Our analysis showed that neither sex (p= 0.135) nor smoking (p = 0.774) had any significant effect on the CNR. However, increased doses of CLO resulted in lower CNR values (p = 0.005). Concomitant use of other psychotropic drugs increased the CNR (p = 0.001). Discussion The results of our study indicate a need for personalized CLO treatment. Assessing the CNR may be useful in identifying CLO interaction with other psychotropic drugs.
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Affiliation(s)
- Anna Mach
- Department of Psychiatry, Medical University of Warsaw, Warsaw, Poland
| | - Anna Wnorowska
- Department of Psychiatry, Medical University of Warsaw, Warsaw, Poland
| | - Marcin Siwek
- Department of Affective Disorders, Jagiellonian University Medical College, Cracow, Poland
| | - Marcin Wojnar
- Department of Psychiatry, Medical University of Warsaw, Warsaw, Poland
- Department of Psychiatry, Addiction Center, University of Michigan, Ann Arbor, MI, United States
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Danek PJ, Basińska-Ziobroń A, Wójcikowski J, Daniel WA. Levomepromazine and clozapine induce the main human cytochrome P450 drug metabolizing enzyme CYP3A4. Pharmacol Rep 2020; 73:303-308. [PMID: 32888176 PMCID: PMC7862537 DOI: 10.1007/s43440-020-00157-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 08/24/2020] [Accepted: 08/26/2020] [Indexed: 11/05/2022]
Abstract
Background Cytochrome P450 (CYP) enzymes are involved in the metabolism of many important endogenous substrates (steroids, melatonin), drugs and toxic xenobiotics. Their induction accelerates drug metabolism and elimination. The present study aimed at examining the inducing abilities of two antipsychotic drugs levomepromazine and clozapine for the main CYPs. Methods The experiments were performed using cryopreserved human hepatocytes. The hepatotoxicity of levomepromazine and clozapine was assessed after exposure to the neuroleptics (LDH test). CYP activities were measured in the incubation medium using the CYP-specific reactions: caffeine 3-N-demethylation (CYP1A1/2), diclofenac 4′-hydroxylation (CYP2C9), perazine N-demethylation (CYP2C19) and testosterone 6β-hydroxylation (CYP3A4). In parallel, CYP mRNA levels were measured in neuroleptic-treated hepatocytes. Results The results indicate that levomepromazine and clozapine induce the expression of main CYP enzyme CYP3A4 in human hepatocytes. Levomepromazine and clozapine at concentrations of 2.5 and 10 µM, respectively, caused a significant increase in the mRNA level and activity of CYP3A4. Both neuroleptics did not produce any changes in CYP1A1/2, CYP2C9 and CYP2C19. Conclusion Levomepromazine and clozapine induce CYP3A4 in human hepatocytes in vitro. Further in vivo studies are advisable to confirm the CYP3A4 induction by levomepromazine and clozapine in the liver, and to assess the effect of these drugs on their own metabolism and on the biotransformation of other co-administered drugs which are the CYP3A4 substrates.
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Affiliation(s)
- Przemysław J Danek
- Department of Pharmacokinetics and Drug Metabolism, Maj Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, 31-343, Kraków, Poland
| | - Agnieszka Basińska-Ziobroń
- Department of Pharmacokinetics and Drug Metabolism, Maj Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, 31-343, Kraków, Poland
| | - Jacek Wójcikowski
- Department of Pharmacokinetics and Drug Metabolism, Maj Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, 31-343, Kraków, Poland
| | - Władysława A Daniel
- Department of Pharmacokinetics and Drug Metabolism, Maj Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, 31-343, Kraków, Poland.
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Schoretsanitis G, Kane JM, Ruan CJ, Spina E, Hiemke C, de Leon J. A comprehensive review of the clinical utility of and a combined analysis of the clozapine/norclozapine ratio in therapeutic drug monitoring for adult patients. Expert Rev Clin Pharmacol 2019; 12:603-621. [PMID: 31075044 DOI: 10.1080/17512433.2019.1617695] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Georgios Schoretsanitis
- Zucker Hillside Hospital, Psychiatry Research, Northwell Health, Glen Oaks, NY, USA
- Hofstra Northwell School of Medicine, Hempstead, NY, USA
- Feinstein Institute for Medical Research, Manhasset, NY, USA
| | - John M. Kane
- Zucker Hillside Hospital, Psychiatry Research, Northwell Health, Glen Oaks, NY, USA
- Hofstra Northwell School of Medicine, Hempstead, NY, USA
- Feinstein Institute for Medical Research, Manhasset, NY, USA
| | - Can-Jun Ruan
- Laboratory of Clinical Psychopharmacology & The National Clinical Research Centre for Mental Disorders & Beijing Key Lab of Mental Disorders, Beijing Anding Hospital, Capital Medical University, Beijing, China
| | - Edoardo Spina
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Christoph Hiemke
- Department of Psychiatry and Psychotherapy, University Medical Center of Mainz, Mainz, Germany
| | - Jose de Leon
- University of Kentucky Mental Health Research Center at Eastern State Hospital, Lexington, KY, USA
- Psychiatry and Neurosciences Research Group (CTS-549), Institute of Neurosciences, University of Granada, Granada, Spain
- Biomedical Research Centre in Mental Health Net (CIBERSAM), Santiago Apostol Hospital, University of the Basque Country, Vitoria, Spain
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