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Cross MR, Savitz ST, Sangaralingham LR, So EL, Ackerman MJ, Noseworthy PA. Sudden Cardiac Death or Ventricular Arrythmia in Patients Taking Levetiracetam or Oxcarbazepine. Neurology 2024; 102:e209177. [PMID: 38560823 DOI: 10.1212/wnl.0000000000209177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 01/05/2024] [Indexed: 04/04/2024] Open
Abstract
BACKGROUND AND OBJECTIVES Levetiracetam is a widely used antiseizure medication. Recent concerns have been raised regarding the potential prolongation of the QT interval by levetiracetam and increased risk of sudden cardiac death. This could have profound implications for patient safety and for prescribing practice. This study assessed the potential association of levetiracetam with cardiac outcomes related to QT interval prolongation. We compared outcomes of patients taking levetiracetam with those taking oxcarbazepine as a comparator medication that has not been associated with prolongation of the QT interval. METHODS The sample included patients who were newly prescribed levetiracetam or oxcarbazepine from January 31, 2010, to December 31, 2019, using administrative claims data from the OptumLabs Data Warehouse (OLDW). The analysis focused on a combined endpoint of sudden cardiac death or ventricular arrythmia, which are both linked to QT interval prolongation. We used a new user design and selected oxcarbazepine as an active comparator with levetiracetam to minimize bias. We used propensity score weighting to balance the levetiracetam and oxcarbazepine cohorts and then performed weighted Cox regressions to evaluate the association of levetiracetam with the combined endpoint. RESULTS We identified 104,655 enrollees taking levetiracetam and 39,596 enrollees taking oxcarbazepine. At baseline, enrollees taking levetiracetam were older, more likely to have diagnosed epilepsy, and more likely to have diagnosed comorbidities including hypertension, cerebrovascular disease, and coronary artery disease. In the main analysis, we found no significant difference between levetiracetam and oxcarbazepine in the rate of the combined endpoint for the Cox proportional hazards model (hazard ratio [HR] 0.79, 95% CI 0.42-1.47) or Cox regression with time-varying characteristics (HR 0.78, 95% CI 0.41-1.50). DISCUSSION When compared with oxcarbazepine, levetiracetam does not correlate with increased risk of ventricular arrythmia and sudden cardiac death. Our finding does not support the concern for cardiac risk to indicate restriction of levetiracetam use nor the requirement of cardiac monitoring when using it. CLASSIFICATION OF EVIDENCE This study provides Class II evidence that sudden cardiac death and ventricular arrythmia are not more frequent in patients older than 17 years newly prescribed levetiracetam, compared with those prescribed oxcarbazepine.
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Affiliation(s)
- Madeline R Cross
- From the Department of Neurology (M.R.C.), Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery (S.T.S.), Division of Health Care Delivery Research (L.R.S., P.A.N.), Division of Epilepsy, Department of Neurology (E.L.S.), and Department of Cardiovascular Diseases (M.J.A., P.A.N.), Mayo Clinic, Rochester, MN
| | - Samuel T Savitz
- From the Department of Neurology (M.R.C.), Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery (S.T.S.), Division of Health Care Delivery Research (L.R.S., P.A.N.), Division of Epilepsy, Department of Neurology (E.L.S.), and Department of Cardiovascular Diseases (M.J.A., P.A.N.), Mayo Clinic, Rochester, MN
| | - Lindsey R Sangaralingham
- From the Department of Neurology (M.R.C.), Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery (S.T.S.), Division of Health Care Delivery Research (L.R.S., P.A.N.), Division of Epilepsy, Department of Neurology (E.L.S.), and Department of Cardiovascular Diseases (M.J.A., P.A.N.), Mayo Clinic, Rochester, MN
| | - Elson L So
- From the Department of Neurology (M.R.C.), Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery (S.T.S.), Division of Health Care Delivery Research (L.R.S., P.A.N.), Division of Epilepsy, Department of Neurology (E.L.S.), and Department of Cardiovascular Diseases (M.J.A., P.A.N.), Mayo Clinic, Rochester, MN
| | - Michael J Ackerman
- From the Department of Neurology (M.R.C.), Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery (S.T.S.), Division of Health Care Delivery Research (L.R.S., P.A.N.), Division of Epilepsy, Department of Neurology (E.L.S.), and Department of Cardiovascular Diseases (M.J.A., P.A.N.), Mayo Clinic, Rochester, MN
| | - Peter A Noseworthy
- From the Department of Neurology (M.R.C.), Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery (S.T.S.), Division of Health Care Delivery Research (L.R.S., P.A.N.), Division of Epilepsy, Department of Neurology (E.L.S.), and Department of Cardiovascular Diseases (M.J.A., P.A.N.), Mayo Clinic, Rochester, MN
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Mann H, Kusayev J, Pandey S, Aryal B, Solaimanzadeh I. A Rare Presentation of Levetiracetam-Induced Torsades De Pointes. Cureus 2023; 15:e40866. [PMID: 37492848 PMCID: PMC10365144 DOI: 10.7759/cureus.40866] [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] [Accepted: 06/23/2023] [Indexed: 07/27/2023] Open
Abstract
Torsades de pointes occurs in the presence of a prolonged QTc interval, which has many congenital and acquired causes. Levetiracetam is a widely used anti-epileptic medication secondary to its favorable safety profile. We present a rare case of a 59-year-old male who developed torsades de pointes and cardiac arrest after levetiracetam administration. To our knowledge, there is only one other case report documenting torsades de pointes after levetiracetam administration, and our case report will be the first documenting cardiac arrest after levetiracetam administration.
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Affiliation(s)
- Henry Mann
- Internal Medicine, One Brooklyn Health System Interfaith Medical Center, Brooklyn, USA
| | | | - Sagar Pandey
- Internal Medicine, One Brooklyn Health System Interfaith Medical Center, Brooklyn, USA
| | - Binit Aryal
- Internal Medicine, One Brooklyn Health System Interfaith Medical Center, Brooklyn, USA
| | - Isaac Solaimanzadeh
- Internal Medicine, One Brooklyn Health System Interfaith Medical Center, Brooklyn, USA
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Chen J, You X, Wu W, Guo G, Lin R, Ke M, Huang P, Lin C. Application of PBPK modeling in predicting maternal and fetal pharmacokinetics of levetiracetam during pregnancy. Eur J Pharm Sci 2023; 181:106349. [PMID: 36496167 DOI: 10.1016/j.ejps.2022.106349] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 11/13/2022] [Accepted: 12/06/2022] [Indexed: 12/12/2022]
Abstract
Levetiracetam is currently being used to treat epilepsy in pregnant women. The plasma concentration of levetiracetam drops sharply during pregnancy, and the inability of pregnant women to maintain therapeutic concentrations can lead to seizures. This study aimed to predict the changes in fetal and maternal plasma exposure to levetiracetam during pregnancy and provide advice on dose adjustment. The physiology-based pharmacokinetics (PBPK) model was developed using PK-Sim and Mobi software, and validated following comparison of the observed plasma concentration and pharmacokinetic parameters. The levetiracetam PBPK model for mother and the fetus at various stages of pregnancy was successfully established and verified. Predictions indicated that the area under the steady-state concentration-time curve for levetiracetam decreased to 83, 62, and 67% of baseline values in the first, second, and third trimesters, respectively. Based on PBPK predictions, the recommended dose of levetiracetam is 1.2, 1.6, and 1.5 times the baseline dose in the first, second, and third trimesters, respectively, not exceeding 4000 mg/day in the third trimester due to fetal safety. The levetiracetam PBPK model for pregnancy was successfully developed and validated, and could provide alternative levetiracetam dosing regimens across the stages of pregnancy.
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Affiliation(s)
- Jiarui Chen
- Department of Pharmacy, the First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong M. Rd, Fuzhou 350005, PR China
| | - Xiang You
- Department of Pharmacy, the First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong M. Rd, Fuzhou 350005, PR China
| | - Wanhong Wu
- Department of Pharmacy, the First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong M. Rd, Fuzhou 350005, PR China
| | - Guimu Guo
- Department of Pharmacy, the First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong M. Rd, Fuzhou 350005, PR China
| | - Rongfang Lin
- Department of Pharmacy, the First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong M. Rd, Fuzhou 350005, PR China
| | - Meng Ke
- Department of Pharmacy, the First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong M. Rd, Fuzhou 350005, PR China
| | - Pinfang Huang
- Department of Pharmacy, the First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong M. Rd, Fuzhou 350005, PR China
| | - Cuihong Lin
- Department of Pharmacy, the First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong M. Rd, Fuzhou 350005, PR China.
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Mahmoud A, Tabassum S, Al Enazi S, Lubbad N, Al Wadei A, Al Otaibi A, Jad L, Benini R. Amelioration of Levetiracetam-Induced Behavioral Side Effects by Pyridoxine. A Randomized Double Blind Controlled Study. Pediatr Neurol 2021; 119:15-21. [PMID: 33823377 DOI: 10.1016/j.pediatrneurol.2021.02.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 02/27/2021] [Accepted: 02/28/2021] [Indexed: 10/22/2022]
Abstract
BACKGROUND Levetiracetam is a relatively new-generation antiseizure drug approved for the treatment of focal and generalized seizures. Despite its favorable side effect profile and minimal drug-drug interactions, neuropsychiatric side effects are reported in up to 13% of children. A few case series have suggested that supplementation of pyridoxine may mitigate these side effects, but controlled trials are lacking. To address this issue, a randomized interventional study was carried out in a pediatric tertiary hospital to qualify and quantify the potential beneficial effect of pyridoxine in attenuating the neuropsychiatric side effects of levetiracetam in children. METHODS A total of 105 children with epilepsy who were taking levetiracetam (as a monotherapy or an adjunct) who showed behavioral symptoms coinciding with the start of levetiracetam, were included. Patients randomly and blindly received either a therapeutic (pyridoxine group, 46 of 105, 44%) or a homeopathic dose of pyridoxine (placebo, 59 of 105, 56%). A 30-item behavioral checklist was used to qualify and quantify the behavioral side effects at baseline and at different time points following initiation of treatment. RESULTS Both placebo and pyridoxine groups experienced a statistical reduction in behavioral scores when compared with baseline. Our study indicated that although there was a placebo effect, the improvement in neuropsychiatric symptoms was more prominent in children who received therapeutic doses of pyridoxine. CONCLUSIONS These data provide clinicians with pertinent evidence-based information that suggests that a trial of pyridoxine in patients who experience behavioral side effects due to the use of levetiracetam may avoid unnecessary change of antiseizure medications.
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Affiliation(s)
- Adel Mahmoud
- Department of Pediatric Neurology, National Neuroscience Institute, King Fahad Medical City, Riyadh, Kingdom of Saudi Arabia.
| | - Sadia Tabassum
- Department of Pediatric Neurology, National Neuroscience Institute, King Fahad Medical City, Riyadh, Kingdom of Saudi Arabia
| | - Shoaa Al Enazi
- Department of Pediatric Neurology, National Neuroscience Institute, King Fahad Medical City, Riyadh, Kingdom of Saudi Arabia
| | - Nahed Lubbad
- Pharmacy service administration, King Fahad Medical City, Riyadh, Kingdom of Saudi Arabia
| | - Ali Al Wadei
- Department of Pediatric Neurology, National Neuroscience Institute, King Fahad Medical City, Riyadh, Kingdom of Saudi Arabia
| | - Ali Al Otaibi
- Department of Pediatric Neurology, National Neuroscience Institute, King Fahad Medical City, Riyadh, Kingdom of Saudi Arabia
| | - Lamya Jad
- Department of Pediatric Neurology, National Neuroscience Institute, King Fahad Medical City, Riyadh, Kingdom of Saudi Arabia
| | - Ruba Benini
- Department of Pediatric Neurology, National Neuroscience Institute, King Fahad Medical City, Riyadh, Kingdom of Saudi Arabia; Sidra Medicine, Division of Pediatric Neurology, Doha, Qatar
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Gul A, Mehreen S. Levetiracetam efficacy on frontal lobe dysfunctions and anger rumination in patients with epilepsy. Epilepsy Behav 2018; 85:28-31. [PMID: 29906698 DOI: 10.1016/j.yebeh.2018.05.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 05/08/2018] [Accepted: 05/09/2018] [Indexed: 11/26/2022]
Abstract
This study compared the frontal lobe functioning and anger rumination between patients with epilepsy and healthy individuals. The second objective was to examine the efficacy of levetiracetam therapy on frontal lobe dysfunctions and anger rumination in patients with epilepsy. Participants (50 patients with epilepsy and 50 healthy individuals) completed the Frontal Assessment Battery (FAB) and Anger Rumination Scale (ARS). The patients had two testing sessions: pre- and post-levetiracetam therapies. The results showed that patients with epilepsy had frontal lobe dysfunctions in contrast with healthy individuals. Patients with epilepsy had higher anger rumination than healthy individuals. Compared with baseline performance, frontal lobe dysfunctions and anger rumination were significantly reduced after three months of levetiracetam therapy in patients with epilepsy. It is concluded that levetiracetam therapy may be beneficial in improving frontal lobe functioning and anger rumination thought pattern in patients with epilepsy. However, further studies are required to confirm this evidence.
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Affiliation(s)
- Amara Gul
- The Islamia University of Bahawalpur, Pakistan.
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Abed El-Gaphar OAM, Abo-Youssef AM, Halal GK. Levetiracetam mitigates lipopolysaccharide-induced JAK2/STAT3 and TLR4/MAPK signaling pathways activation in a rat model of adjuvant- induced arthritis. Eur J Pharmacol 2018; 826:85-95. [PMID: 29501867 DOI: 10.1016/j.ejphar.2018.02.041] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 02/21/2018] [Accepted: 02/27/2018] [Indexed: 12/12/2022]
Abstract
Levetiracetam (LEV), a novel anti-epileptic drug that has been demonstrated with an anti-inflammatory effect, but the exact mechanisms of its action remain to be fully defined. The present study aimed to evaluate the possible effects of LEV on lipopolysaccharides (LPS)-induced Janus kinase-signal transducers and activators of transcription (JAK/STAT) as well as toll-like receptor 4 (TLR4)/ mitogen activated protein kinase (MAPK) signaling pathways activation in adjuvant induced arthritis (AIA). Rats were allocated into normal control, three arthritic control groups: Complete Freund's Adjuvant (CFA) (0.4 ml/3days/12days), LPS (100 µg/kg/day), CFA+LPS, and three treated groups: CFA+LEV, LPS+LEV and CFA+LPS+LEV. LEV was administered in a dose 50 mg/kg/day for 15 day. After 28 days, tissue samples were collected for assessment of phosphorylated JAK2, STAT3, TLR4, MAPK and cathepsin K quantitative expression in synovium. Additionally, Serum samples were used for biochemical evaluation of interleukin-6 (IL-6), interleukin-1beta (IL-1B), LPS, anti-citrullinated protein antibody (ACPA) and 8-hydroxydeoxyguanosine (8-OHdG). Histopathological and macroscopical examinations of joints were also performed to support our study. Results indicated that LEV exerted its anti-inflammatory effect through inhibiting LPS-dependent phosphorylation of JAK2/STAT3 signaling. It significantly suppressed TLR4 and MAPK expressions, thereby decreasing release of inflammatory cytokines IL-1β, IL-6.LEV exhibited a potent inhibitory effect on cathepsin K and 8-OHdG parallel to confirmatory histopathological and macroscopical findings. In conclusion, LEV has a powerful therapeutic effect on adjuvant induced arthritis in rats and its mechanisms are strongly related to inhibiting excessive activation of JAK2-STAT3 and TLR4 pathways. This may add a new approach for treatment of RA.
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Affiliation(s)
| | - Amira M Abo-Youssef
- Pharmacology and Toxicology Department, Faculty of Pharmacy, Beni-Suef University, Beni-Suef, Egypt.
| | - Gouda Kamel Halal
- Pharmacology and Toxicology department, Faculty of Pharmacy, Al-Azhar University, Cairo, Egypt.
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Mazza M, Martini A, Scoppetta M, Mazza S. Effect of levetiracetam on depression and anxiety in adult epileptic patients. Prog Neuropsychopharmacol Biol Psychiatry 2008; 32:539-43. [PMID: 18031881 DOI: 10.1016/j.pnpbp.2007.10.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2007] [Revised: 10/16/2007] [Accepted: 10/23/2007] [Indexed: 11/13/2022]
Abstract
BACKGROUND Interictal depression is common in patients with epilepsy and it significantly impacts quality of life. Some studies indicate that levetiracetam (LEV) may have mood stabilizing properties. METHODS Twenty-five adults with uncontrolled partial seizures and concomitant depressive symptoms were treated with LEV. Patients were evaluated for depression and anxiety with several psychometric measures, including: Montgomery and Asberg Depression Rating Scale (MADRS), Hamilton Depression Rating Scale (HDRS), Zung Self-rating Scale for Depression (Z-SDS), Hamilton Anxiety Rating Scale (HARS), Zung Self-rating Scale for Anxiety (Z-SAS). RESULTS Evaluations after 5 weeks and after 3 months of LEV treatment demonstrated significant improvement in depression and anxiety. CONCLUSIONS This uncontrolled study suggests that treatment with LEV may also improve depression and anxiety in patients with partial seizures. However, the sample of patients is limited and the possibility of a placebo effect cannot be excluded. These findings must be considered preliminary and should be replicated under placebo-controlled conditions.
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Affiliation(s)
- Marianna Mazza
- Institute of Psychiatry and Psychology, Catholic University of Sacred Heart, Rome, Via Ugo De Carolis, 48 00136 Rome, Italy.
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Sheshashena Reddy T, Sita Devi P. Validation of a high-performance thin-layer chromatographic method with densitometric detection for quantitative analysis of two anticonvulsants in tablets. JPC-J PLANAR CHROMAT 2007. [DOI: 10.1556/jpc.2007.6007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Jain DS, Subbaiah G, Sanyal M, Pal U, Shrivastav PS. Determination of levetiracetam in human plasma by liquid chromatography/electrospray tandem mass spectrometry and its application to bioequivalence studies. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2006; 20:2539-47. [PMID: 16878346 DOI: 10.1002/rcm.2623] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The first liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the determination of levetiracetam, an antiepileptic drug, in human plasma is described. The plasma filtrate obtained after solid-phase extraction (SPE), using a polymer-based, hydrophilic-lipophilic balanced (HLB) cartridge, was submitted directly to a short column LC/MS/MS assay. There was no significant matrix effect on the analysis. For validation of the method, the recovery of the free analytes was compared to that from an optimized extraction method, and the analyte stability was examined under conditions mimicking sample storage, handling, and analytical procedures. The extraction procedure yielded extremely clean extracts with a recovery of 79.95% and 89.02% for levetiracetam and the internal standard (IS), respectively. The intra-assay and inter-assay precision for the samples at the lower limit of quantitation (LLOQ) were 6.33 and 6.82%, respectively. The calibration curves were linear for the dynamic range of 0.5 to 50 microg/mL with a correlation coefficient r >/= 0.9971. The intra-assay accuracy at LLOQ, LQC, MQC, and HQC levels ranged from 81.60 to 95.40, 93.00 to 103.47, 95.97 to 104.09, and 91.15 to 95.18%, respectively, while the inter-assay accuracy at LLOQ, LQC, MQC and HQC levels varied from 80.20 to 95.40, 88.53 to 107.53, 95.97 to 108.45, and 91.15 to 112.70%, respectively. The method is rugged and fast with a total instrumental run time of 2 min. The method was successfully applied for bioequivalence studies in human subject samples after oral administration of 1000 mg immediate release (IR) formulations.
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Affiliation(s)
- Deepak S Jain
- Department of Chemistry, School of Sciences, Gujarat University, Navrangpura, Ahmedabad 380 009, India
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Chatterjee A, Louis ED, Frucht S. Levetiracetam in the treatment of paroxysmal kinesiogenic choreoathetosis. Mov Disord 2002; 17:614-5. [PMID: 12112221 DOI: 10.1002/mds.10118] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Anticonvulsants are frequently used in the treatment of paroxysmal kinesiogenic choreoathetosis (PKC). Although they are often extremely effective in eliminating paroxysmal movements, short- and long-term side-effects may limit their use in young patients. Levetiracetam (Keppra), a novel antiepileptic drug approved for the treatment of partial seizures is well tolerated in patients with epilepsy. We report on the use of levetiracetam in the treatment of PKC. Levetiracetam was effective in eliminating paroxysmal events and should be considered as an alternative to standard antiepileptic medications in this disorder.
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Affiliation(s)
- Anjan Chatterjee
- The Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, New York, USA
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Abstract
New epilepsy treatment options are becoming available to physicians and may help provide safe and effective seizure management in patients for whom traditional drug therapies have been unsuccessful. Presented here is a brief discussion on the screening models used to test drugs for efficacy against various seizure types and the mechanisms of action and pharmacology of antiepilepsy drugs. This is followed by a more detailed review of the clinical pharmacology of the latest three antiepilepsy drugs introduced to the United States: levetiracetam, oxcarbazepine, and zonisamide. All three appear to have advantages over some traditional antiepilepsy drugs and with more clinical experience may replace them in certain seizure types or epilepsy syndromes.
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Affiliation(s)
- James W Wheless
- Department of Neurology, University of Texas at Houston, 77030, USA.
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Abstract
PURPOSE We investigated the effect of the new antiepileptic drug (AED) levetiracetam (LEV) on different types of high-voltage-activated (HVA) Ca2+ channels in freshly isolated CA1 hippocampal neurons of rats. METHODS Patch-clamp recordings of HVA Ca2+ channel activity were obtained from isolated hippocampal CA1 neurons. LEV was applied by gravity flow from a pipette placed near the cell, and solution changes were made by electromicrovalves. Ca2+ channel blockers were used for separation of the channel subtypes. RESULTS The currents were measured in controls and after application of 1-200 microM LEV. LEV irreversibly inhibited the HVA calcium current by approximately 18% on the average. With a prepulse stimulation protocol, which can eliminate direct inhibition of Ca2+ channels by G proteins, we found that G proteins were not involved in the pathways underlying the LEV inhibitory effect. This suggested that the inhibitory effect arises from a direct action of LEV on the channel molecule. The blocking mechanism of LEV was not related to changes in steady-state activation or inactivation of Ca2+ channels. LEV also did not influence the rundown of the HVA Ca2+ current during experimental protocols lasting approximately 10 min. Finally, LEV at the highest concentration used (200 microM) did not influence the activity of L-, P- or Q-type Ca2+ channels in CA1 neurons, while selectively influencing the activity of N-type calcium channels. The maximal effect on these channels separated from other channel types was approximately 37%. CONCLUSIONS Our results provide evidence that LEV selectively inhibits N-type Ca2+ channels of CA1 pyramidal hippocampal neurons. These data suggest the existence of a subtype of N-type channels sensitive to LEV, which might be involved in the molecular basis of its antiepileptic action.
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