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Pisani F, Pisani LR, Barbieri MA, de Leon J, Spina E. Optimization of Therapy in Patients with Epilepsy and Psychiatric Comorbidities: Key Points. Curr Neuropharmacol 2023; 21:1755-1766. [PMID: 35619263 PMCID: PMC10514544 DOI: 10.2174/1570159x20666220526144314] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 04/24/2022] [Accepted: 05/25/2022] [Indexed: 11/22/2022] Open
Abstract
Psychiatric disorder comorbidity in patients with epilepsy (PWE) is very frequent with a mean percentage prevalence of up to 50% and even higher. Such a high frequency suggests that epilepsy and psychiatric disorders might share common pathological pathways. Various aspects contribute in making the matter very complex from a therapeutic point of view. Some antiseizure medications (ASMs), namely valproic acid, carbamazepine, and lamotrigine, have mood-stabilising effects and are routinely used for the treatment of bipolar disorder in patients who do not have epilepsy. Pregabalin and, to a lesser extent, gabapentin, exerts anxiolytic effects. However, several ASMs, in particular levetiracetam, topiramate, and perampanel, may contribute to psychiatric disorders, including depression, aggressive behaviour, and even psychosis. If these ASMs are prescribed, the patient should be monitored closely. A careful selection should be made also with psychotropic drugs. Although most of these can be safely used at therapeutic doses, bupropion, some tricyclic antidepressants, maprotiline, and clozapine may alter seizure threshold and facilitate epileptic seizures. Interactions between ASMs and psychotropic medication may make it difficult to predict individual response. Pharmacokinetic interactions can be assessed with drug monitoring and are consequently much better documented than pharmacodynamic interactions. Another aspect that needs a careful evaluation is patient adherence to treatment. Prevalence of non-adherence in PWE and psychiatric comorbidities is reported to reach values even higher than 70%. A careful evaluation of all these aspects contributes in optimizing therapy with a positive impact on seizure control, psychiatric wellbeing, and quality of life.
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Affiliation(s)
- Francesco Pisani
- Department of Clinical and Experimental Medicine, University of Messina, Italy
| | | | | | - Jose de Leon
- Mental Health Research Center at Eastern State Hospital, Lexington, KY, USA and Psychiatry and Biomedical Research Centre in Mental Health Net (CIBERSAM), Santiago Apostol Hospital, University of the Basque Country, Vitoria, Spain
| | - Edoardo Spina
- Department of Clinical and Experimental Medicine, University of Messina, Italy
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Zaccara G, Franco V. Pharmacokinetic Interactions Between Antiseizure and Psychiatric Medications. Curr Neuropharmacol 2023; 21:1666-1690. [PMID: 35611779 PMCID: PMC10514545 DOI: 10.2174/1570159x20666220524121645] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 03/27/2022] [Accepted: 05/03/2022] [Indexed: 11/22/2022] Open
Abstract
Antiseizure medications and drugs for psychiatric diseases are frequently used in combination. In this context, pharmacokinetic interactions between these drugs may occur. The vast majority of these interactions are primarily observed at a metabolic level and result from changes in the activity of the cytochrome P450 (CYP). Carbamazepine, phenytoin, and barbiturates induce the oxidative biotransformation and can consequently reduce the plasma concentrations of tricyclic antidepressants, many typical and atypical antipsychotics and some benzodiazepines. Newer antiseizure medications show a lower potential for clinically relevant interactions with drugs for psychiatric disease. The pharmacokinetics of many antiseizure medications is not influenced by antipsychotics and anxiolytics, while some newer antidepressants, namely fluoxetine, fluvoxamine and viloxazine, may inhibit CYP enzymes leading to increased serum concentrations of some antiseizure medications, including phenytoin and carbamazepine. Clinically relevant pharmacokinetic interactions may be anticipated by knowledge of CYP enzymes involved in the biotransformation of individual medications and of the influence of the specific comedication on the activity of these CYP enzymes. As a general rule, these interactions can be managed by careful evaluation of clinical response and, when indicated, individualized dosage adjustments guided by measurement of drugs serum concentrations, especially if pharmacokinetic interactions may cause any change in seizure control or signs of toxicity. Further studies are required to improve predictions of pharmacokinetic interactions between antiseizure medications and drugs for psychiatric diseases providing practical helps for clinicians in the clinical setting.
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Affiliation(s)
| | - Valentina Franco
- Department of Internal Medicine and Therapeutics, Clinical and Experimental Pharmacology Unit, University of Pavia, Pavia, Italy
- IRCCS Mondino Foundation, Pavia, Italy
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Spina E, Pisani F, de Leon J. Clinically significant pharmacokinetic drug interactions of antiepileptic drugs with new antidepressants and new antipsychotics. Pharmacol Res 2016; 106:72-86. [DOI: 10.1016/j.phrs.2016.02.014] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 02/08/2016] [Accepted: 02/11/2016] [Indexed: 12/14/2022]
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Mula M. The pharmacological management of psychiatric comorbidities in patients with epilepsy. Pharmacol Res 2016; 107:147-153. [PMID: 27001226 DOI: 10.1016/j.phrs.2016.03.022] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 03/16/2016] [Accepted: 03/17/2016] [Indexed: 01/04/2023]
Abstract
Psychiatric disorders represent a frequent comorbidity in patients with epilepsy affecting quality of life, morbidity and mortality. Evidence-based data on the management of these conditions are limited but a number of recommendations are now available to guide clinical practice. The present paper reviews the pharmacological treatment of psychiatric problems in epilepsy with special attention to data coming from randomised controlled trials (RCTs), pharmacological interactions with AEDs and the issue of seizure worsening during treatment with psychotropic drugs. Epidemiologically or clinically relevant psychiatric conditions are discussed namely mood and anxiety disorders, psychoses and attention deficit hyperactivity disorder.
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Affiliation(s)
- Marco Mula
- Atkinson Morley Regional Neuroscience Centre, St. Georges University Hospitals NHS Foundation Trust, London, United Kingdom; South West London & St. Georges Mental Health Trust, London, United Kingdom; Institute of Medical and Biomedical Sciences, St. Georges University of London, United Kingdom.
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van Gaalen J, Kerstens FG, Maas RPPWM, Härmark L, van de Warrenburg BPC. Drug-induced cerebellar ataxia: a systematic review. CNS Drugs 2014; 28:1139-53. [PMID: 25391707 DOI: 10.1007/s40263-014-0200-4] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND AND OBJECTIVES Cerebellar ataxia can be induced by a large number of drugs. We here conducted a systemic review of the drugs that can lead to cerebellar ataxia as an adverse drug reaction (ADR). METHODS We performed a systematic literature search in Pubmed (1966 to January 2014) and EMBASE (1988 to January 2014) to identify all of the drugs that can have ataxia as an ADR and to assess the frequency of drug-induced ataxia for individual drugs. Furthermore, we collected reports of drug-induced ataxia over the past 20 years in the Netherlands by querying a national register of ADRs. RESULTS Drug-induced ataxia was reported in association with 93 individual drugs (57 from the literature, 36 from the Dutch registry). The most common groups were antiepileptic drugs, benzodiazepines, and antineoplastics. For some, the number needed to harm was below 10. Ataxia was commonly reversible, but persistent symptoms were described with lithium and certain antineoplastics. CONCLUSIONS It is important to be aware of the possibility that ataxia might be drug-induced, and for some drugs the relative frequency of this particular ADR is high. In most patients, symptoms occur within days or weeks after the introduction of a new drug or an increase in dose. In general, ataxia tends to disappear after discontinuation of the drug, but chronic ataxia has been described for some drugs.
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Affiliation(s)
- J van Gaalen
- Department of Neurology 935 and Donders Institute for Brain, Cognition, and Behaviour, Radboud University Medical Centre, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands,
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Italiano D, Spina E, de Leon J. Pharmacokinetic and pharmacodynamic interactions between antiepileptics and antidepressants. Expert Opin Drug Metab Toxicol 2014; 10:1457-89. [PMID: 25196459 DOI: 10.1517/17425255.2014.956081] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
INTRODUCTION Antiepileptic-antidepressant combinations are frequently used by clinicians; their pharmacokinetic (PK) and pharmacodynamic (PD) drug interactions (DIs) have not been well studied but are frequently likely to be clinically relevant. AREAS COVERED This article provides a comprehensive review of PK DIs between antiepileptics and antidepressants. In the absence of PD DI studies, PD information on pharmacological mechanisms and studies on efficacy and safety of individual drugs are reviewed. EXPERT OPINION The clinical relevance of the inductive properties of carbamazepine, phenytoin, phenobarbital and primidone and the inhibitory properties of valproic acid and some antidepressants are well understood; correction factors are provided if appropriate DI studies have been completed. More PK studies are needed for: i) antiepileptics with potent inductive effects for all recently approved antidepressants; ii) high doses of mild CYP3A4 inducers, such as clobazam, eslicarbazepine, oxcarbazepine, rufinamide and topiramate for reboxetine and vilazodone; iii) valproate as a possible inhibitor, mild inducer or both a mild inducer and competitive inhibitor of some antidepressants; and iv) inhibitory effects of long-term fluoxetine use on clobazam, lacosamide, phenobarbital, primidone, carbamazepine, felbamate, tiagabine and zonisamide. Possible synergistic or additive beneficial PD DIs in generalized anxiety disorder, chronic pain, migraine prophylaxis, weight control and menopausal symptoms need study.
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Affiliation(s)
- Domenico Italiano
- University of Messina, Department of Clinical and Experimental Medicine , Messina , Italy
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Korczyn AD, Schachter SC, Brodie MJ, Dalal SS, Engel J, Guekht A, Hecimovic H, Jerbi K, Kanner AM, Landmark CJ, Mares P, Marusic P, Meletti S, Mula M, Patsalos PN, Reuber M, Ryvlin P, Štillová K, Tuchman R, Rektor I. Epilepsy, cognition, and neuropsychiatry (Epilepsy, Brain, and Mind, part 2). Epilepsy Behav 2013; 28:283-302. [PMID: 23764496 PMCID: PMC5016028 DOI: 10.1016/j.yebeh.2013.03.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/28/2013] [Indexed: 12/13/2022]
Abstract
Epilepsy is, of course, not one disease but rather a huge number of disorders that can present with seizures. In common, they all reflect brain dysfunction. Moreover, they can affect the mind and, of course, behavior. While animals too may suffer from epilepsy, as far as we know, the electrical discharges are less likely to affect the mind and behavior, which is not surprising. While the epileptic seizures themselves are episodic, the mental and behavioral changes continue, in many cases, interictally. The episodic mental and behavioral manifestations are more dramatic, while the interictal ones are easier to study with anatomical and functional studies. The following extended summaries complement those presented in Part 1.
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Affiliation(s)
- Amos D. Korczyn
- Sackler School of Medicine, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Steven C. Schachter
- Center for Integration of Medicine and Innovative Technology, Harvard Medical School, Boston, MA, USA
| | | | - Sarang S. Dalal
- Zukunftskolleg & Department of Psychology, University of Konstanz, Germany
- Lyon Neuroscience Research Center (CRNL), INSERM U1028, CNRS UMR5292, University Lyon I, Brain Dynamics and Cognition Team, Lyon, France
| | | | - Alla Guekht
- Russian National Research Medical University, Moscow City Hospital No. 8 for Neuropsychiatry, Moscow, Russia
| | - Hrvoje Hecimovic
- Zagreb Epilepsy Center, Department of Neurology, University Hospital, Zagreb, Croatia
| | - Karim Jerbi
- Lyon Neuroscience Research Center (CRNL), INSERM U1028, CNRS UMR5292, University Lyon I, Brain Dynamics and Cognition Team, Lyon, France
| | - Andres M. Kanner
- Department of Neurology, University of Miami, Miller School of Medicine, Miami FL, USA
| | - Cecilie Johannessen Landmark
- Department of Pharmacy and Biomedical Science, Oslo, Norway
- Akershus University College of Applied Sciences, Oslo, Norway
| | - Pavel Mares
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Petr Marusic
- Department of Neurology, Charles University in Prague, 2nd Faculty of Medicine, Motol University Hospital, Prague, Czech Republic
| | - Stefano Meletti
- Department of Biomedical Sciences, Metabolism, and Neuroscience, University of Modena and Reggio Emilia, Modena, Italy
| | - Marco Mula
- Amedeo Avogadro University, Novara, Italy
| | - Philip N. Patsalos
- Department of Clinical and Experimental Epilepsy, UCL-Institute of Neurology, London and Epilepsy Society, Chalfont St Peter, UK
| | - Markus Reuber
- Academic Neurology Unit, University of Sheffield, Royal Hallamshire Hospital, Sheffield, UK
| | - Philippe Ryvlin
- Service de neurologie fonctionnelle et d’épileptologie, Hôpital Neurologique, HCL TIGER, CRNL, INSERM U1028, UMR-CNRS 5292, Université Lyon-1, Lyon, France
| | - Klára Štillová
- Masaryk University, Brno Epilepsy Center, St. Anne’s Hospital and School of Medicine, and Central European Institute of Technology (CEITEC), Brno, Czech Republic
| | - Roberto Tuchman
- Autism and Neurodevelopment Program, Miami Children’s Hospital Dan Marino Center, Departments of Neurology and Psychiatry, Herbert Wertheim College of Medicine, Florida International University, FL, USA
| | - Ivan Rektor
- Masaryk University, Brno Epilepsy Center, St. Anne’s Hospital and School of Medicine, and Central European Institute of Technology (CEITEC), Brno, Czech Republic
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Kanner AM. The treatment of depressive disorders in epilepsy: what all neurologists should know. Epilepsia 2013; 54 Suppl 1:3-12. [PMID: 23458461 DOI: 10.1111/epi.12100] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
One of every three patients with epilepsy (PWE) will experience a depressive disorder in the course of their life, often associated with anxiety symptoms or a full blown anxiety disorder. Clearly, the high prevalence of these psychiatric comorbidities calls for their early identification and management. This article provides practical strategies in the management of depressive episodes in PWE. Contrary to long-held beliefs, the use of antidepressant drugs are safe in PWE when used at therapeutic doses. Antidepressant drugs of the selective serotonin reuptake inhibitor (SSRI) or serotonin-norepinephrine reuptake inhibitor (SNRI) families are the first line of therapy in depressive disorders, and failure to achieve complete symptom remission after a trial of an SSRI or SNRI at optimal doses should be followed by a second trial with a drug from the other antidepressant family. In developing countries, antidepressant drugs of these two antidepressant families are not always available, and tricyclic antidepressants (TCAs) are the drugs of choice. Although there are no differences in efficacy among the three families of antidepressants, TCAs have a lower tolerability and higher toxicity, with greater mortality risk associated with cardiotoxic effects in overdoses. Cognitive behavior therapy is another treatment modality that has been shown to be effective in the treatment of depressive disorders in patients with and without epilepsy. Its use should be considered together with pharmacotherapy or by itself.
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Affiliation(s)
- Andres M Kanner
- Comprehensive Epilepsy Program and Department of Neurology, University of Miami, Miller School of Medicine, Miami, Florida 33136, USA.
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Sayyah M, Majzoob S, Sayyah M. Metabolic and toxicological considerations for obsessive-compulsive disorder drug therapy. Expert Opin Drug Metab Toxicol 2013; 9:657-73. [PMID: 23521155 DOI: 10.1517/17425255.2013.783011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Obsessive-compulsive disorder (OCD) affects the daily life of the patients. Chronic nature of this disease and the need for long-term high-dose drug therapy for its maintenance increase the risk of metabolic and toxicological complications. AREAS COVERED In this concise article, the metabolic and toxicological aspects of major medication categories prescribed in OCD, such as serotonin-specific reuptake inhibitors, tricyclic antidepressant (clomipramine), serotonin-norepinephrine reuptake inhibitors, and atypical antipsychotics indicated in OCD (both Food and Drug Administration-approved and off-label) are discussed. EXPERT OPINION The most critical point in pharmacotherapy of OCD is the need for the high-dose and long-term use of drugs. In OCD, generally the higher doses of applicable drugs than those used in depression are required, often exceeding the recommended maximum dose. Moreover, such high doses should be given for at least 10 - 12 weeks to ensure the adequate treatment duration for the clinical effects to emerge. This long-term high-dose maintenance therapy increases the risk of drug toxicity and adverse effects. Physicians should take extra care in periodical assessment of signs and symptoms of metabolic and toxicological complications in patients. Subjective symptoms reported by patients should be carefully assessed and not attributed to obsessive nature of the patients.
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Affiliation(s)
- Mohammad Sayyah
- Pasteur Institute of Iran, Department of Physiology and Pharmacology, Tehran, Iran
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10
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Mula M, Schmitz B, Sander JW. The pharmacological treatment of depression in adults with epilepsy. Expert Opin Pharmacother 2008; 9:3159-68. [DOI: 10.1517/14656560802587024] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Kanner AM, Gidal BE. Pharmacodynamic and pharmacokinetic interactions of psychotropic drugs with antiepileptic drugs. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2008; 83:397-416. [PMID: 18929094 DOI: 10.1016/s0074-7742(08)00022-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Co-morbid psychiatric disorders are relatively frequent in patients with epilepsy. The prevalence rates of mood and anxiety disorders, psychotic disorders and attention deficit/hyperactivity disorder have been found to be significantly higher in patients with epilepsy than in the general population. While co-morbid psychiatric disorders have frequently been considered as complications of the seizure disorder, there is an increasing body of literature that points to a complex relationship between psychiatric and seizure disorders. Because of this, it is crucial that clinicians consider the presence of co-morbid psychiatric disorders when planning the treatment of patients with epilepsy. Having a clear understanding of the pharmacodynamic and pharmacokinetic interactions between antiepileptic drugs and psychotropic drugs is of the essence to avert unnecessary adverse events and loss of efficacy of psychotropic drugs. This chapter provides a practical review on the use of psychotropic drugs for the treatment of these psychiatric co-morbidities in patients with epilepsy.
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Lee SY, Lee ST, Kim JW. Contributions of CYP2C9/CYP2C19 genotypes and drug interaction to the phenytoin treatment in the Korean epileptic patients in the clinical setting. BMB Rep 2007; 40:448-52. [PMID: 17562299 DOI: 10.5483/bmbrep.2007.40.3.448] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We examined the contribution of CYP2C9 and CYP2C19 genotypes and drug interactions to the phenytoin metabolism among 97 Korean epileptic patients to determine if pharmacogenetic testing could be utilized in routine clinical practice. The CYP2C9 polymorphism is a wellknown major genetic factor responsible for phenytoin metabolism. The CYP219 polymorphism, with a high incidence of variant alleles, has a minor influence on phenytoin treated Koran patients. Using a multiple regression model for evaluation of the CYP2C9 and CYP2C19 genotypes, together with other non-genetic variables, we explained 39.6% of the variance in serum phenytoin levels. Incorporation of genotyping for CYP2C9 and CYP2C19 into a clinical practice may be of some help in the determination of phenytoin dosage. However, because concurrent drug treatment is common in patients taking phenytoin and many environmental factors are likely to play a role in drug metabolism, these factors may overwhelm the relevance of CYP polymorphisms in the clinical setting. Further investigations with an approach to dose assessment that includes comprehensive interpretation of both pharmacogenetic and pharmacokinetic data along with understanding of the mechanism of drug interactions in dosage adjustment is warranted.
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Affiliation(s)
- Soo-Youn Lee
- Department of Laboratory Medicine and Genetics, Sungkyunkwan University School of Medicine and Samsung Medical Center, Seoul, Korea
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Alonso-Navarro H, Jiménez-Jiménez FJ, García-Agúndez JA. Papel del polimorfismo genético CYP2C19 en los efectos adversos a fármacos y en el riesgo para diversas enfermedades. Med Clin (Barc) 2006; 126:697-706. [PMID: 16759580 DOI: 10.1157/13088772] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
There are a great number of polymorphic genes in the human genome. Many of them codify enzymes that metabolizes drugs and xenobiotic agents, including carcinogens. Among the better known of them, there are a number of isozymes of the microsomal oxidative system (CYP3A4, CYP2C9, CYP2C19 y CYP2D6). This article reviews the following issues: a) frequency of presentation of the "poor metabolizer" genotype and/or phenotype for substrates of CYP2C19; b) role of CYP2C19 polymorphism on the metabolism of some drugs (mephenytoine and other antiepileptic drugs, proton pump inhibitors, several antidepressants and anxyolitics, the antimalaria aggent proguanyl, and propranolol, among others, use this metabolic pathway), and c) possible role of CYP2C19 polymorphism in the risk for development of neoplasia and other diseases (systemic lupus erythematosus, psoriasis, hip osteonecrosis, Alzheimer's disease, amyotrophic lateral sclerosis, essential tremor).
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Brandt C, Pohlmann-Eden B. Interaktionen zwischen Antiepileptika und Psychopharmaka. ZEITSCHRIFT FÜR EPILEPTOLOGIE 2006. [DOI: 10.1007/s10309-006-0185-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Abstract
Phenytoin toxicity may result from intentional overdose, dosage adjustments, drug interactions, or alterations in physiology. Intoxication manifests predominantly as nausea, central nervous system dysfunction (particularly confusion, nystagmus, and ataxia), with depressed conscious state, coma, and seizures occurring in more severe cases. Cardiac complications such as arrhythmias and hypotension are rare in cases of phenytoin ingestion, but they may be seen in parenteral administration of phenytoin or fosphenytoin. Deaths are unlikely after phenytoin intoxication alone. A greatly increased half-life in overdose due to zero-order pharmacokinetics can result in a prolonged duration of symptoms and thus prolonged hospitalization with its attendant complications. The mainstay of therapy for a patient with phenytoin intoxication is supportive care. Treatment includes attention to vital functions, management of nausea and vomiting, and prevention of injuries due to confusion and ataxia. There is no antidote, and there is no evidence that any method of gastrointestinal decontamination or enhanced elimination improves outcome. Activated charcoal should be considered if the patient presents early; however, the role of multiple-dose activated charcoal is controversial. Experimental studies have proven increased clearance rates, but this effect has not been translated into clinical benefit. There is no evidence that any invasive method of enhanced elimination (such as plasmapheresis, hemodialysis, or hemoperfusion) provides any benefit. This article provides an overview of phenytoin pharmacokinetics and the clinical manifestations of toxicity, followed by a detailed review of the various treatment modalities.
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Affiliation(s)
- Simon Craig
- Emergency Registrar, Monash Medical Centre, Clayton, Victoria, Australia.
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Sandson NB, Armstrong SC, Cozza KL. An overview of psychotropic drug-drug interactions. PSYCHOSOMATICS 2005; 46:464-94. [PMID: 16145193 DOI: 10.1176/appi.psy.46.5.464] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The psychotropic drug-drug interactions most likely to be relevant to psychiatrists' practices are examined. The metabolism and the enzymatic and P-glycoprotein inhibition/induction profiles of all antidepressants, antipsychotics, and mood stabilizers are described; all clinically meaningful drug-drug interactions between agents in these psychotropic classes, as well as with frequently encountered nonpsychotropic agents, are detailed; and information on the pharmacokinetic/pharmacodynamic results, mechanisms, and clinical consequences of these interactions is presented. Although the range of drug-drug interactions involving psychotropic agents is large, it is a finite and manageable subset of the much larger domain of all possible drug-drug interactions. Sophisticated computer programs will ultimately provide the best means of avoiding drug-drug interactions. Until these programs are developed, the best defense against drug-drug interactions is awareness and focused attention to this issue.
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Affiliation(s)
- Neil B Sandson
- Division of Education and Residency Training, Sheppard Pratt Health System, Towson, MD, USA
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Unger M, Frank A. Simultaneous determination of the inhibitory potency of herbal extracts on the activity of six major cytochrome P450 enzymes using liquid chromatography/mass spectrometry and automated online extraction. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2004; 18:2273-2281. [PMID: 15384148 DOI: 10.1002/rcm.1621] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Here we describe a liquid chromatography/mass spectrometry (LC/MS) method with automated online extraction (LC/LC/MS) to simultaneously determine the in vitro inhibitory potency of herbal extracts on six major human drug-metabolising cytochrome P450 enzymes. Substrates were incubated with a commercially available mixture of CYP1A2/2C8/2C9/2C19/2D6 and 3A4 from baculovirus-infected insect cells and the resulting metabolites were quantified with LC/LC/MS using electrospray ionisation in the selected ion monitoring mode. Consistent inhibitory activities were obtained for known inhibitors and plant extracts using the enzyme/substrate cocktail and the individual enzymes/substrates. Popular herbal remedies including devil's claw root (Harpagophytum procumbens), feverfew herb (Tanacetum parthenium), fo-ti root (Polygonum multiflorum), kava-kava root (Piper methysticum), peppermint oil (Mentha piperita), eucalyptus oil (Eucalyptus globulus), red clover blossom (Trifolium pratense) and grapefruit juice (GJ; Citrus paradisi) could be identified as inhibitors of the applied CYP enzymes with IC(50) values between 20 and 1000 microg/mL.
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Affiliation(s)
- Matthias Unger
- Institute of Pharmacy and Food Chemistry, Julius Maximilians-University Würzburg, 97074 Würzburg, Germany.
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Patsalos PN, Perucca E. Clinically important drug interactions in epilepsy: interactions between antiepileptic drugs and other drugs. Lancet Neurol 2003; 2:473-81. [PMID: 12878435 DOI: 10.1016/s1474-4422(03)00483-6] [Citation(s) in RCA: 297] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Antiepileptic drugs (AEDs) are commonly prescribed for long periods, up to a lifetime, and many patients will require treatment with other agents for the management of concomitant or intercurrent conditions. When two or more drugs are prescribed together, clinically important interactions can occur. Among old-generation AEDs, carbamazepine, phenytoin, phenobarbital, and primidone are potent inducers of hepatic enzymes, and decrease the plasma concentration of many psychotropic, immunosuppressant, antineoplastic, antimicrobial, and cardiovascular drugs, as well as oral contraceptive steroids. Most new generation AEDs do not have clinically important enzyme inducing effects. Other drugs can affect the pharmacokinetics of AEDs; examples include the stimulation of lamotrigine metabolism by oral contraceptive steroids and the inhibition of carbamazepine metabolism by certain macrolide antibiotics, antifungals, verapamil, diltiazem, and isoniazid. Careful monitoring of clinical response is recommended whenever a drug is added or removed from a patient's AED regimen.
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Affiliation(s)
- Philip N Patsalos
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College London, London, UK.
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Pharmacoepidemiology and drug safety. Pharmacoepidemiol Drug Saf 2001; 10:345-60. [PMID: 11760498 DOI: 10.1002/pds.549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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