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Ion-Channel Antiepileptic Drugs: An Analytical Perspective on the Therapeutic Drug Monitoring (TDM) of Ezogabine, Lacosamide, and Zonisamide. ANALYTICA 2021. [DOI: 10.3390/analytica2040016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The term seizures includes a wide array of different disorders with variable etiology, which currently represent one of the most important classes of neurological illnesses. As a consequence, many different antiepileptic drugs (AEDs) are currently available, exploiting different activity mechanisms and providing different levels of performance in terms of selectivity, safety, and efficacy. AEDs are currently among the psychoactive drugs most frequently involved in therapeutic drug monitoring (TDM) practices. Thus, the plasma levels of AEDs and their metabolites are monitored and correlated to administered doses, therapeutic efficacy, side effects, and toxic effects. As for any analytical endeavour, the quality of plasma concentration data is only as good as the analytical method allows. In this review, the main techniques and methods are described, suitable for the TDM of three AEDs belonging to the class of ion channel agents: ezogabine (or retigabine), lacosamide, and zonisamide. In addition to this analytical overview, data are provided, pertaining to two of the most important use cases for the TDM of antiepileptics: drug–drug interactions and neuroprotection activity studies. This review contains 146 references.
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Pre-Clinical Assessment of the Nose-to-Brain Delivery of Zonisamide After Intranasal Administration. Pharm Res 2020; 37:74. [PMID: 32215749 DOI: 10.1007/s11095-020-02786-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 02/17/2020] [Indexed: 12/13/2022]
Abstract
PURPOSE Zonisamide clinical indications are expanding beyond the classic treatment of epileptic seizures to Parkinson's disease and other neurodegenerative diseases. However, the systemic safety profile of zonisamide may compromise its use as a first-line drug in any clinical condition. Since zonisamide is marketed as oral formulations, the present study aimed at exploring the potential of the intranasal route to centrally administer zonisamide, evaluating the systemic bioavailability of zonisamide and comparing its brain, lung and kidney pharmacokinetics after intranasal, oral and intravenous administrations. METHODS In vitro cell studies demonstrated that zonisamide and proposed thermoreversible gels did not affect the viability of RPMI 2650 or Calu-3 cells. Thereafter, male CD-1 mice were randomly administered with zonisamide by oral (80 mg/kg), intranasal or intravenous (16.7 mg/kg) route. At predefined time points, animals were sacrificed and plasma and tissues were collected to quantify zonisamide and describe its pharmacokinetics. RESULTS Intranasal route revealed a low absolute bioavailability (54.95%) but the highest value of the ratio between the area under the curve (AUC) between brain and plasma, suggesting lower systemic adverse events and non-inferior effects in central nervous system comparatively to intravenous and oral routes. Furthermore, drug targeting efficiency and direct transport percentage into the brain were 149.54% and 33.13%, respectively, corroborating that a significant fraction of zonisamide suffers direct nose-to-brain transport. Lung and kidney exposures obtained after intranasal administration were lower than those observed after intravenous injection. CONCLUSIONS This pre-clinical investigation demonstrates a direct nose-to-brain delivery of zonisamide, which may be a promising strategy for the treatment of central diseases.
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Martínez-Ávila JC, García Bartolomé A, García I, Dapía I, Tong HY, Díaz L, Guerra P, Frías J, Carcás Sansuan AJ, Borobia AM. Pharmacometabolomics applied to zonisamide pharmacokinetic parameter prediction. Metabolomics 2018; 14:70. [PMID: 30830352 DOI: 10.1007/s11306-018-1365-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 04/25/2018] [Indexed: 10/16/2022]
Abstract
INTRODUCTION Zonisamide is a new-generation anticonvulsant antiepileptic drug metabolized primarily in the liver, with subsequent elimination via the renal route. OBJECTIVES Our objective was to evaluate the utility of pharmacometabolomics in the detection of zonisamide metabolites that could be related to its disposition and therefore, to its efficacy and toxicity. METHODS This study was nested to a bioequivalence clinical trial with 28 healthy volunteers. Each participant received a single dose of zonisamide on two separate occasions (period 1 and period 2), with a washout period between them. Blood samples of zonisamide were obtained from all patients at baseline for each period, before volunteers were administered any medication, for metabolomics analysis. RESULTS After a Lasso regression was applied, age, height, branched-chain amino acids, steroids, triacylglycerols, diacyl glycerophosphoethanolamine, glycerophospholipids susceptible to methylation, phosphatidylcholines with 20:4 FA (arachidonic acid) and cholesterol ester and lysophosphatidylcholine were obtained in both periods. CONCLUSION To our knowledge, this is the only research study to date that has attempted to link basal metabolomic status with pharmacokinetic parameters of zonisamide.
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Affiliation(s)
- J C Martínez-Ávila
- Clinical Pharmacology Department, La Paz University Hospital, School of Medicine, IdiPAZ, Autonomous University of Madrid, Madrid, Spain.
| | - A García Bartolomé
- Clinical Pharmacology Department, La Paz University Hospital, School of Medicine, IdiPAZ, Autonomous University of Madrid, Madrid, Spain
| | - I García
- Clinical Pharmacology Department, La Paz University Hospital, School of Medicine, IdiPAZ, Autonomous University of Madrid, Madrid, Spain
| | - I Dapía
- Medical and Molecular Genetics Institute (INGEMM), La Paz University Hospital, Rare Diseases Networking Biomedical Research Center (CIBERER), ISCIII, Madrid, Spain
| | - Hoi Y Tong
- Clinical Pharmacology Department, La Paz University Hospital, School of Medicine, IdiPAZ, Autonomous University of Madrid, Madrid, Spain
| | - L Díaz
- Clinical Pharmacology Department, La Paz University Hospital, School of Medicine, IdiPAZ, Autonomous University of Madrid, Madrid, Spain
| | - P Guerra
- Clinical Pharmacology Department, La Paz University Hospital, School of Medicine, IdiPAZ, Autonomous University of Madrid, Madrid, Spain
| | - J Frías
- Clinical Pharmacology Department, La Paz University Hospital, School of Medicine, IdiPAZ, Autonomous University of Madrid, Madrid, Spain
| | - A J Carcás Sansuan
- Clinical Pharmacology Department, La Paz University Hospital, School of Medicine, IdiPAZ, Autonomous University of Madrid, Madrid, Spain.
| | - A M Borobia
- Clinical Pharmacology Department, La Paz University Hospital, School of Medicine, IdiPAZ, Autonomous University of Madrid, Madrid, Spain
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Romigi A, Femia EA, Fattore C, Vitrani G, Di Gennaro G, Franco V. Zonisamide in the management of epilepsy in the elderly. Clin Interv Aging 2015; 10:931-7. [PMID: 26089654 PMCID: PMC4467644 DOI: 10.2147/cia.s50819] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Zonisamide (ZNS), a second-generation antiepileptic drug, indicated as add-on treatment of focal epilepsy, has been recently approved as monotherapy for the treatment of partial seizures in adults affected by newly diagnosed epilepsy in Europe. Evidence on the efficacy and tolerability of antiepileptic drugs in the elderly is still lacking as these patients are frequently excluded from clinical trials. Here, a comprehensive overview of available data regarding the use of ZNS in the treatment of epilepsy in elderly people is provided. In a pooled analysis conducted in patients aged ≥65 years, no new/unexpected safety findings have emerged. Few data from uncontrolled investigations suggest that ZNS may be effective and well tolerated when administered as monotherapy or adjunctive antiepileptic treatment in the elderly. However, evidence from these observational studies is less than satisfactory, and randomized controlled trials focused on these patients are still needed.
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Affiliation(s)
- Andrea Romigi
- Istituto Neurologico Mediterraneo, IRCCS Neuromed, Pozzilli (IS), Italy
- Neurophysiopathology Department, University of Rome Tor Vergata, Rome, Italy
| | - Eti A Femia
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, Milano, Italy
| | - Cinzia Fattore
- Clinical Trial Centre & Antiepileptic Drugs, C. Mondino National Neurological Institute, Pavia, Italy
| | - Giuseppe Vitrani
- Istituto Neurologico Mediterraneo, IRCCS Neuromed, Pozzilli (IS), Italy
| | | | - Valentina Franco
- Clinical Trial Centre & Antiepileptic Drugs, C. Mondino National Neurological Institute, Pavia, Italy
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Zonisamide as a treatment for partial epileptic seizures: a systematic review. Adv Ther 2014; 31:276-88. [PMID: 24522856 DOI: 10.1007/s12325-014-0104-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Indexed: 10/25/2022]
Abstract
Although the majority of people with epilepsy have a good prognosis and their seizures can be well controlled with pharmacotherapy, up to one-third of patients can develop drug-resistant epilepsy, especially those patients with partial seizures. This unmet need has driven considerable efforts over the last few decades aimed at developing and testing newer antiepileptic agents to improve seizure control. One of the most promising antiepileptic drugs of the new generation is zonisamide, a benzisoxazole derivative chemically unrelated to other anticonvulsant agents. In this article, the authors present the results of a systematic literature review summarizing the current evidence on the efficacy and tolerability of zonisamide for the treatment of partial seizures. Of particular interest within this updated review are the recent data on the use of zonisamide as monotherapy, as they might open new therapeutic avenues.
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Patsalos PN. Drug Interactions with the Newer Antiepileptic Drugs (AEDs)—Part 1: Pharmacokinetic and Pharmacodynamic Interactions Between AEDs. Clin Pharmacokinet 2013; 52:927-66. [DOI: 10.1007/s40262-013-0087-0] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Brodie MJ, Ben-Menachem E, Chouette I, Giorgi L. Zonisamide: its pharmacology, efficacy and safety in clinical trials. Acta Neurol Scand 2012:19-28. [PMID: 23106522 DOI: 10.1111/ane.12016] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Zonisamide is a benzisoxazole derivative, chemically unrelated to other antiepileptic drugs, that appears to have multiple mechanisms of action, including inhibition of Na(+) channels and reduction of T-type Ca(2+) currents. It is currently licensed in Europe and the USA for adjunctive treatment of partial seizures in adults, and in Europe as monotherapy for treatment of partial seizures in adults with newly diagnosed epilepsy. Zonisamide displays predictable, dose-dependent pharmacokinetics and has a half-life of ~60 h, allowing once- or twice-daily administration. It has a low potential for interactions with other medications, including oral contraceptives. The clinical efficacy of adjunctive zonisamide therapy has been established in four pivotal, phase III, randomized, double-blind, placebo-controlled trials, which together included approximately 850 patients, aged 12-77 years, with refractory partial epilepsy. In all four trials, zonisamide 300-600 mg/day resulted in significant reductions in median total seizure rates vs placebo, and zonisamide was generally well tolerated; the most frequently reported adverse events being somnolence, dizziness and anorexia/weight loss. Subanalysis of the primary European trial indicated that zonisamide was effective when administered as first-line adjunctive treatment, and a long-term extension to the same trial demonstrated that the efficacy and safety/tolerability of adjunctive zonisamide was sustained for up to 36 months. Once-daily monotherapy with zonisamide (200-500 mg/day) has been shown to be non-inferior to, and as well tolerated as, twice-daily monotherapy with controlled-release carbamazepine (400-1200 mg/day) in adults with newly diagnosed partial epilepsy. Zonisamide has also been shown to have favourable long-term retention rates, an important indication of its overall effectiveness.
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Affiliation(s)
- M. J. Brodie
- Epilepsy Unit; Western Infirmary; Glasgow; Scotland
| | - E. Ben-Menachem
- Institute for Clinical Neuroscience and Physiology; Sahlgrenska Academy, University of Gothenburg; Gothenburg; Sweden
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Jankovic SM, Dostic M. Choice of antiepileptic drugs for the elderly: possible drug interactions and adverse effects. Expert Opin Drug Metab Toxicol 2011; 8:81-91. [DOI: 10.1517/17425255.2012.645535] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Verdier MC, Bentué-Ferrer D, Tribut O. Suivi thérapeutique pharmacologique du zonisamide. Therapie 2010; 65:29-34. [DOI: 10.2515/therapie/2009062] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Revised: 12/01/2009] [Accepted: 12/01/2009] [Indexed: 11/20/2022]
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Effectiveness and tolerability of zonisamide in children with epilepsy: A retrospective review. Seizure 2010; 19:31-5. [DOI: 10.1016/j.seizure.2009.10.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Revised: 10/27/2009] [Accepted: 10/29/2009] [Indexed: 11/17/2022] Open
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Neuman MG, Shear NH, Malkiewicz IM, Kessas M, Lee AW, Cohen L. Predicting possible zonisamide hypersensitivity syndrome. Exp Dermatol 2008; 17:1045-51. [DOI: 10.1111/j.1600-0625.2008.00748.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Kothare SV, Kaleyias J. Zonisamide: review of pharmacology, clinical efficacy, tolerability, and safety. Expert Opin Drug Metab Toxicol 2008; 4:493-506. [PMID: 18433351 DOI: 10.1517/17425255.4.4.493] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Zonisamide (ZNS), a sulphonamide derivative, is a new-generation anticonvulsant with multiple potential mechanisms that contribute to its antiepileptic efficacy and may also explain its as yet incompletely assessed utility for non-seizure disorders such as headaches, neuropathic pain, and weight loss. OBJECTIVE A review of the pharmacokinetics, pharmacodynamics, evidence for efficacy in different seizure types and non-seizure conditions, adverse effects, and tolerability of ZNS is presented. METHODS A review of all manuscripts published in the English literature on ZNS was performed in preparing this manuscript. RESULTS/CONCLUSIONS ZNS has a broad label for use in Japan, while the regulatory bodies in the USA and Europe have approved it for use only as an adjunctive therapy for partial seizures in adults. It has favorable pharmacokinetic characteristics, proven efficacy in seizure disorders, and is well tolerated in long-term use.
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Affiliation(s)
- Sanjeev V Kothare
- Pediatric Sleep Medicine Training Program, Division of Epilepsy & Clinical Neurophysiology, Department of Neurology, Children's Hospital Boston, Harvard Medical School, Boston, MA 02115, USA.
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Baulac M, Leppik IE. Efficacy and safety of adjunctive zonisamide therapy for refractory partial seizures. Epilepsy Res 2007; 75:75-83. [PMID: 17553670 DOI: 10.1016/j.eplepsyres.2007.04.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2006] [Revised: 03/21/2007] [Accepted: 04/23/2007] [Indexed: 10/23/2022]
Abstract
An approach to the selection of appropriate antiepileptic drugs (AEDs) for inclusion in polytherapy is to take into account both the efficacy of a drug and also its mechanism of action and pharmacokinetic profile. The AED zonisamide is licensed in Europe and the USA for use as adjunctive therapy in adult patients with partial onset epilepsy. Four pivotal clinical studies in patients with refractory partial seizures demonstrated that zonisamide as an add-on was most effective at doses of >or=300 mg/day, with responder rates (>or=50% reduction from baseline in seizure frequency) ranging from 28 to 47% for all seizures. In addition, zonisamide has a unique combination of multiple mechanisms of action that are potentially complementary with concomitant AEDs. Zonisamide has no clinically relevant effects on the pharmacokinetics of other commonly used AEDs, however, co-administration with cytochrome P450 3A4 (CYP3A4) inducers or inhibitors may change zonisamide's pharmacokinetic profile. Zonisamide is well tolerated with the majority of adverse events being mild-to-moderate and generally manageable. The tolerability of zonisamide has also been shown to improve with slower drug titration and duration of drug treatment. These characteristics suggest that zonisamide may be suitable as a key adjunct in rational polytherapy.
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Affiliation(s)
- Michel Baulac
- Department of Neurology, University of Paris 6, Bat. Paul Castaigne Hopital de la Pitie-Salpetrierre, 47 Boulevard de l'Hopital, 75013 Paris, France.
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Abstract
Polypharmacy is a widely employed treatment strategy in epilepsy, particularly for individuals with poorly controlled seizures. Drug combinations should be carefully considered to minimize the potential for unfavorable interactions. Older-generation antiepileptic drugs (AEDs) are well known for their pharmacokinetic interaction potential, which generally results from alterations in the metabolism of concomitant drugs due to effects on the cytochrome P450 (CYP) and uridine glucuronyl transferase enzyme systems. Newer agents, such as zonisamide, are less likely to cause adverse drug interactions. A series of interaction studies has revealed zonisamide to be without effect on the steady-state pharmacokinetics of carbamazepine, phenytoin, sodium valproate, or lamotrigine. However, zonisamide is principally inactivate by CY3A4-dependent reduction. Consequently, carbamazepine, phenytoin, and phenobarbital all increase its clearance, an interaction that may necessitate a dosage increase, but which will also permit more rapid attainment of steady-state zonisamide concentrations. Otherwise, zonisamide is essentially devoid of clinically significant interactions with other AEDs, oral contraceptives and, indeed, all other classes of therapeutic agents investigated to date. As a result, it is reasonable to conclude that zonisamide has a favorable pharmacokinetic profile and that it may be a useful and uncomplicated agent when employed as adjunctive therapy in refractory epilepsy.
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Affiliation(s)
- Graeme Sills
- Epilepsy Unit, University Division of Cardiovascular and Medical Sciences, Western Infirmary, Glasgow, Scotland, UK.
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Baulac M. Introduction to zonisamide. Epilepsy Res 2006; 68 Suppl 2:S3-9. [PMID: 16413170 DOI: 10.1016/j.eplepsyres.2005.11.004] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2005] [Revised: 11/01/2005] [Accepted: 11/02/2005] [Indexed: 11/23/2022]
Abstract
Zonisamide (Zonegran), a novel antiepileptic drug (AED) approved recently in Europe as adjunctive therapy for refractory partial seizures in adults, has been used extensively in Japan and the United States. A substantial body of clinical experience has accumulated over a 14-year period, allowing the properties and pharmacologic/clinical profiles of zonisamide to be clearly defined. Zonisamide is structurally distinct from other AEDs and has multiple and complementary mechanisms of action, which likely contribute to its efficacy across a broad range of epilepsy types. Zonisamide has a long T1/2 enabling once-daily dosing, linear pharmacokinetics and minimal interaction with other drugs; plasma levels of commonly administered AEDs and oral contraceptives are unaffected by concomitant zonisamide. Effective control of partial seizures (up to 51% decrease in seizure frequency) is attained at doses of >or=300 mg/day, and optimal titration and maintenance dosing schedules have been established. The adverse event profile is well defined; in common with most AEDs, most adverse events are central nervous system-related (e.g. somnolence, dizziness, tiredness). Adverse events may be minimised with appropriate patient management. Zonisamide therefore has many characteristics considered desirable in an AED and represents a valuable addition to the therapeutic options for treating epilepsy in Europe.
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Affiliation(s)
- Michel Baulac
- Department of Neurology, University of Paris 6, Bat. Paul Castaigne, Hopital de la Pitie-Salpetriere, 47 Bld de l'Hopital, 75013 Paris, France.
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Abstract
The aim of this brief communication is to update our recent review on therapeutic drug monitoring (TDM) of the newer antiepileptic drugs (AEDs). The potential value of TDM is discussed in relation to their mode of action and their pharmacokinetic proper-ties. Data on the relationships between serum concentrations and clinical efficacy are limited, and few studies have been designed primarily to study these relationships. As yet there are no generally accepted target ranges for any of the new AEDs. For most drugs a wide range in serum concentration is associated with clinical efficacy,and there is a considerable overlap in serum concentrations related to toxicity and lack of clinical efficacy. Although the available documentation is clearly insufficient, the pharmacological properties of some of the drugs suggest that they may be suitable candidates for TDM. The primary role of TDM for both the newer and established AEDs is to identify an individual's optimum concentration and thus establish a reference value in that patient.
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Abstract
Zonisamide (Zonegran, Excegran) is a new-generation, broad-spectrum antiepileptic drug (AED) currently approved as adjunctive therapy for the treatment of medically refractory partial seizures in adults in the US and as adjunctive therapy or monotherapy in the control of partial and generalised seizures in adults and children in Japan and Korea. Either as adjunctive therapy or monotherapy, zonisamide effectively reduces the frequency of partial seizures, with or without secondary generalisation to tonic-clonic seizures, in adults and children with epilepsy. The drug is generally well tolerated and, additionally, has a favourable pharmacokinetic profile permitting once- or twice-daily administration. Direct head-to-head comparisons with other AEDs would be beneficial in fully defining the place of zonisamide in therapy. In the meantime, adjunctive therapy or monotherapy with zonisamide is a convenient, useful option for the management of partial seizures, including those refractory to other AEDs.
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Current awareness: Pharmacoepidemiology and drug safety. Pharmacoepidemiol Drug Saf 2005. [DOI: 10.1002/pds.1026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Brodie MJ, Duncan R, Vespignani H, Solyom A, Bitenskyy V, Lucas C. Dose-dependent Safety and Efficacy of Zonisamide: A Randomized, Double-blind, Placebo-controlled Study in Patients with Refractory Partial Seizures. Epilepsia 2005; 46:31-41. [PMID: 15660766 DOI: 10.1111/j.0013-9580.2005.14704.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE To evaluate the safety and efficacy of zonisamide (ZNS) as adjunctive treatment in patients with refractory localization-related epilepsy. METHODS This was a double-blind, placebo-controlled study of adjunctive ZNS in 351 patients with refractory partial seizures receiving a stable regimen of one to three antiepileptic drugs (AEDs). Patients were randomized to placebo or ZNS, 100 mg, 300 mg, or 500 mg/day (2:1:1:2) after a 12-week baseline. Dose titration was undertaken over a 6-week titration phase, which was followed by an 18-week fixed-dose assessment phase. Primary efficacy parameters were the differences between ZNS, 500 mg/day, and placebo in the change from baseline in frequency of complex partial (CP) seizures during the fixed-dose assessment phase and in the proportion of CP responders (> or =50% decrease from baseline in seizure frequency). Safety and tolerability also were assessed. RESULTS Compared with placebo, the highest dose of ZNS (500 mg/day) resulted in a significantly greater decrease in CP seizure frequency from baseline (51.2% vs. 16.3%; p < 0.0001) and a significantly higher proportion of CP responders (52.3% vs. 21.3%; p < 0.001). Both ZNS, 500 mg/day, and 300 mg/day were statistically superior to placebo in reducing the frequency of "all seizures" and simple partial (SP) + CP seizures. For all seizures, a significant dose-response relation was observed (p < 0.0001). The most common adverse events were somnolence, headache, dizziness, and nausea during the titration phase and headache and pharyngitis during the fixed-dose assessment phase. CONCLUSIONS ZNS provides dose-dependent, effective, and generally well-tolerated adjunctive therapy in patients with partial seizures.
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Affiliation(s)
- Martin J Brodie
- Division of Cardiovascular and Medical Sciences, Western Infirmary, Glasgow, United Kingdom.
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