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Vu LC, Piccenna L, Kwan P, O'Brien TJ. New-onset epilepsy in the elderly. Br J Clin Pharmacol 2018; 84:2208-2217. [PMID: 29856080 PMCID: PMC6138506 DOI: 10.1111/bcp.13653] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 05/02/2018] [Accepted: 05/02/2018] [Indexed: 12/30/2022] Open
Abstract
People who are 60 years old and older have the highest incidence of developing new-onset epilepsy. The increase of the ageing population has resulted in a greater number of patients with new-onset epilepsy or at risk of developing the condition. Previously published review articles regarding epilepsy in older patients have had a broad focus, including people who were diagnosed with epilepsy in their childhood or middle age. The present review focuses on the causes, treatment, prognosis and psychosocial impact of new-onset epilepsy in people aged ≥60 years. Following a search of the medical electronic databases and relevant references, we identified 22 studies overall that met the inclusion criteria. Only four randomized clinical trials (RCTs) were identified that compared different antiepileptic drug treatments in this population, demonstrating that newer-generation antiepileptic drugs (e.g. lamotrigine and levetiracetam) were generally better tolerated. One uncontrolled study provided promising evidence of good outcomes and safety for surgical resection as a treatment for people with uncontrolled seizures. Five studies reported that people ≥60 years with new-onset epilepsy have significant cognitive impairments (e.g. memory loss) and psychological issues including depression, anxiety and fatigue. We found that there is limited evidence to guide treatment in people with Alzheimer's disease and epilepsy. The specific features of new-onset epilepsy in this target population significantly influences the choice of treatment. Cognitive and psychiatric screening before treatment may be useful for management. Two studies with proposed guidelines were identified but no formal clinical practice guidelines exist for this special population to assist with appropriate management. There is a need for more RCTs that investigate effective treatments with limited side effects. More research studies on the psychosocial effects of new-onset epilepsy, and long-term outcomes, for people aged ≥60 years are also required.
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Affiliation(s)
- Lily Chi Vu
- Melbourne Brain Centre at the Royal Melbourne Hospital; Departments of Medicine and Neurology, Royal Melbourne HospitalUniversity of MelbourneMelbourneVictoria3050Australia
| | - Loretta Piccenna
- Departments of Neuroscience and Neurology, Central Clinical SchoolMonash University, The Alfred HospitalMelbourneVictoria3004Australia
| | - Patrick Kwan
- Melbourne Brain Centre at the Royal Melbourne Hospital; Departments of Medicine and Neurology, Royal Melbourne HospitalUniversity of MelbourneMelbourneVictoria3050Australia
- Departments of Neuroscience and Neurology, Central Clinical SchoolMonash University, The Alfred HospitalMelbourneVictoria3004Australia
| | - Terence J. O'Brien
- Melbourne Brain Centre at the Royal Melbourne Hospital; Departments of Medicine and Neurology, Royal Melbourne HospitalUniversity of MelbourneMelbourneVictoria3050Australia
- Departments of Neuroscience and Neurology, Central Clinical SchoolMonash University, The Alfred HospitalMelbourneVictoria3004Australia
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Nakashima H, Oniki K, Nishimura M, Ogusu N, Shimomasuda M, Ono T, Matsuda K, Yasui-Furukori N, Nakagawa K, Ishitsu T, Saruwatari J. Determination of the Optimal Concentration of Valproic Acid in Patients with Epilepsy: A Population Pharmacokinetic-Pharmacodynamic Analysis. PLoS One 2015; 10:e0141266. [PMID: 26484865 PMCID: PMC4617862 DOI: 10.1371/journal.pone.0141266] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 10/05/2015] [Indexed: 01/12/2023] Open
Abstract
Valproic acid (VPA) is one of the most widely prescribed antiepileptic drugs for the treatment of epileptic seizures. Although it is well known that the doses of VPA and its plasma concentrations are highly correlated, the plasma concentrations do not correlate well with the therapeutic effects of the VPA. In this study, we developed a population-based pharmacokinetic (PK)-pharmacodynamic (PD) model to determine the optimal concentration of VPA according to the clinical characteristics of each patient. This retrospective study included 77 VPA-treated Japanese patients with epilepsy. A nonlinear mixed-effects model best represented the relationship between the trough concentrations of VPA at steady-state and an over 50% reduction in seizure frequency. The model was fitted using a logistic regression model, in which the logit function of the probability was a linear function of the predicted trough concentration of VPA. The model showed that the age, seizure locus, the sodium channel neuronal type I alpha subunit rs3812718 polymorphism and co-administration of carbamazepine, clonazepam, phenytoin or topiramate were associated with an over 50% reduction in the seizure frequency. We plotted the receiver operating characteristic (ROC) curve for the logit(Pr) value of the model and the presence or absence of a more than 50% reduction in seizure frequency, and the areas under the curves with the 95% confidence interval from the ROC curve were 0.823 with 0.793-0.853. A logit(Pr) value of 0.1 was considered the optimal cut-off point (sensitivity = 71.8% and specificity = 80.4%), and we calculated the optimal trough concentration of VPA for each patient. Such parameters may be useful to determine the recommended therapeutic concentration of VPA for each patient, and the procedure may contribute to the further development of personalized pharmacological therapy for epilepsy.
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Affiliation(s)
- Hiroo Nakashima
- Division of Pharmacology and Therapeutics, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Kentaro Oniki
- Division of Pharmacology and Therapeutics, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Miki Nishimura
- Division of Pharmacology and Therapeutics, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Naoki Ogusu
- Division of Pharmacology and Therapeutics, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Masatsugu Shimomasuda
- Division of Pharmacology and Therapeutics, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Tatsumasa Ono
- Division of Pharmacology and Therapeutics, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Kazuki Matsuda
- Division of Pharmacology and Therapeutics, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Norio Yasui-Furukori
- Department of Neuropsychiatry, Graduate School of Medicine, Hirosaki University, Hirosaki, Japan
| | - Kazuko Nakagawa
- Division of Pharmacology and Therapeutics, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
- Center for Clinical Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Takateru Ishitsu
- Kumamoto Saishunso National Hospital, Koshi, Japan
- Kumamoto Ezuko Ryoiku Iryo Center, Kumamoto, Japan
| | - Junji Saruwatari
- Division of Pharmacology and Therapeutics, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
- Center for Clinical Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
- * E-mail:
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Coppola G, Besag F, Cusmai R, Dulac O, Kluger G, Moavero R, Nabbout R, Nikanorova M, Pisani F, Verrotti A, von Stülpnagel C, Curatolo P. Current role of rufinamide in the treatment of childhood epilepsy: literature review and treatment guidelines. Eur J Paediatr Neurol 2014; 18:685-90. [PMID: 24929673 DOI: 10.1016/j.ejpn.2014.05.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 05/14/2014] [Accepted: 05/18/2014] [Indexed: 11/18/2022]
Abstract
PURPOSE The literature on the efficacy and safety of rufinamide in childhood-onset epilepsy syndromes currently includes approximately 600 paediatric patients. This paper summarizes the views of a panel of experienced European epileptologists with regard to the current role of rufinamide in the treatment of childhood epilepsies. RESULTS Rufinamide is effective in decreasing the seizure frequency in the Lennox-Gastaut syndrome (LGS), especially tonic and atonic seizures. It might consequently be preferred to other drugs as a second-line treatment for LGS when drop-attacks are frequent. The mean responder rate in the published studies is 38% with seizure freedom achieved in 2.4% of patients. Rufinamide has shown some efficacy in epileptic encephalopathies other than LGS. It can be also effective as adjunctive therapy in children and adolescents with drug-resistant partial seizures. The available data suggest that rufinamide has an acceptable risk/benefit ratio with quite a low risk of aggravating seizures. Common adverse effects (somnolence, nausea and vomiting) are usually mild and self-limiting; they are more frequently observed during titration than in the maintenance phase, suggesting that low escalation rates might be associated with fewer adverse effects. Rufinamide appears to have a favourable cognitive profile compared with other antiepileptic drugs. CONCLUSION Rufinamide is only approved for adjunctive treatment of seizures associated with LGS in children 4 years of age and older. There are very few data on rufinamide treatment at the onset of LGS or early in the course of the disorder; whether early treatment will improve outcome has yet to be determined.
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Affiliation(s)
- Giangennaro Coppola
- Child and Adolescent Neuropsychiatry, Medical School, University of Salerno, Italy
| | - Frank Besag
- South Essex Partnership University NHS Foundation Trust, Bedfordshire, United Kingdom
| | - Raffaella Cusmai
- Neurology Unit, "Bambino Gesù" Children's Hospital, IRCCS, Rome, Italy
| | - Olivier Dulac
- Inserm U1129, Neuropediatrics Department, Necker-Enfants Malades Hospital, APHP, Paris Descartes University, CEA, Orsay, France
| | - Gerhard Kluger
- Clinic for Neuropediatrics and Neurological Rehabilitation, Epilepsy-Center for Children and Adolescents, Vogtareuth, Germany; Paracelsus Medical University, Salzburg, Austria
| | - Romina Moavero
- Department of Systems Medicine, Child Neurology and Psychiatry Unit, Tor Vergata University Hospital of Rome, Italy
| | - Rima Nabbout
- Centre de Reference Epilepsies Rares, Inserm U1129, Neuropediatrics Department, Necker-Enfants Malades Hospital, APHP, Paris Descartes University, CEA, Orsay, France
| | | | | | | | - Celina von Stülpnagel
- Clinic for Neuropediatrics and Neurological Rehabilitation, Epilepsy-Center for Children and Adolescents, Vogtareuth, Germany
| | - Paolo Curatolo
- Department of Systems Medicine, Child Neurology and Psychiatry Unit, Tor Vergata University Hospital of Rome, Italy.
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Wechsler RT, Li G, French J, O'Brien TJ, D'Cruz O, Williams P, Goodson R, Brock M. Conversion to lacosamide monotherapy in the treatment of focal epilepsy: results from a historical-controlled, multicenter, double-blind study. Epilepsia 2014; 55:1088-98. [PMID: 24915838 PMCID: PMC4477913 DOI: 10.1111/epi.12681] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/30/2014] [Indexed: 02/05/2023]
Abstract
OBJECTIVE To evaluate the efficacy and safety of conversion to lacosamide 400 mg/day monotherapy in adults with focal epilepsy. METHODS This historical-controlled, double-blind study (NCT00520741) enrolled patients aged 16-70 years on stable doses of 1-2 antiepileptic drugs (AEDs) and experiencing 2-40 partial-onset seizures per 28 days during the 8-week prospective Baseline. Patients were randomized to lacosamide 400 or 300 mg/day (3:1 ratio), starting at 200 mg/day and titrated over 3 weeks to randomized dose. Patients then withdrew background AEDs over 6 weeks and entered a 10-week Monotherapy Phase. The primary assessment was the Kaplan-Meier-predicted percentage of patients on 400 mg/day in the full analysis set (FAS) meeting ≥ 1 predefined seizure-related exit criterion by day 112, compared with the historical-control threshold (65.3%). RESULTS Four hundred twenty-five patients were enrolled and were eligible for safety analyses (400 mg/day, n = 319; 300 mg/day, n = 106). A total of 271 (63.8%) of 425 patients completed the Lacosamide Maintenance Phase (combined AED Withdrawal and Monotherapy Phases). Among 284 patients in the 400 mg/day group in the FAS, 82 (28.9%) met ≥ 1 exit criterion; the Kaplan-Meier-predicted exit percentage at day 112 for 400 mg/day (30.0%; 95% confidence interval [CI] 24.6-35.5%) was lower than the historical control. When exit events, withdrawal due to treatment-emergent adverse events (TEAEs), and withdrawal due to lack of efficacy were summed (n = 90), the predicted exit percentage (32.3%; 95% CI 26.8-37.8%) was also lower than the historical control. Most patients receiving 400 mg/day reported some improvement on the Clinical Global Impression of Change (75.4%) and Patient Global Impression of Change (74.3%). Overall, the most common (>10%) TEAEs were dizziness (24.0%), headache (14.4%), nausea (13.4%), convulsion (11.5%), somnolence (10.4%), and fatigue (10.1%); most (74.1%) were mild-to-moderate in intensity. Seventy-two patients (16.9%) discontinued due to TEAEs. Seventeen patients (4%, all receiving 400 mg/day) experienced serious AEs. SIGNIFICANCE Lacosamide 400 mg/day monotherapy was effective, with a favorable safety profile in patients with focal epilepsy.
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Appel K. [Not Available]. Fortschr Neurol Psychiatr 2013; 81:301. [PMID: 23936921 DOI: 10.1055/s-0033-1349271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
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Langdon EH. Switching to generic: the need for physician and patient consent when substituting antiepileptic medication. J Contemp Health Law Policy 2008; 25:166-195. [PMID: 19137751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Affiliation(s)
- Evan H Langdon
- The Catholic University of America, Columbus School of Law, USA
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Abstract
KEY POINTS (1) A large number of treatment options have shown generally moderate efficacy in the treatment of diabetic painful neuropathy.(2) Tricyclic antidepressants are the mainstay of therapy, with anticonvulsants, opioids and serotonin-noradrenaline reuptake inhibitors also having a place.(3) Head-to-head trials of current treatments are needed. Meanwhile, selection of therapeutic agents should be individualised.
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Affiliation(s)
- Kate McKeage
- Wolters Kluwer Health | Adis, Auckland, New Zealand
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Abstract
The availability of generic products of antiepileptic drugs (AEDs) has raised the following concerns: (1) Do generic AEDs work as well as brand AEDs in terms of their efficacy, safety and quality? (2) Can generic AEDs be used as substitutions for brand AEDs? and (3) Can generic products of AEDs be used interchangeably? The traditional average bioequivalence analysis addresses concern 1 but does not provide a complete adequate response to concerns 2 and 3. Drug interchangeability can be classified as drug prescribability or drug switchability. Drug prescribability refers to the situation where a patient is treated for the first time so that either a brand or a bioequivalent generic AED can be chosen. Drug switchability refers to the situation in which a brand AED is switched to a bioequivalent generic product of the same AED. The traditional average bioequivalence approach is sufficient to evaluate the prescribability of generic products, but does not ensure the switchability between prescribable formulations. The necessity of assuring switchability of two formulations can be addressed by individual bioequivalence. While the switch to generic AEDs is well tolerated by many patients and in general cost-effective, seizure control should not be sacrificed on the basis of cost alone, as the major end point in treating epilepsy with AEDs is seizure control without side effects. Until we have individual (within patient) bioequivalence data on generic AEDs and/or the tools to a priori identify the subset of patients susceptible to the generic switch, a switch of AED products in seizure-free patients is not recommended.
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Affiliation(s)
- Meir Bialer
- Department of Pharmaceutics, School of Pharmacy and David R. Bloom Center for Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel.
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Odermatt P, Ly S, Simmala C, Angerth T, Phongsamouth V, Mac TL, Ratsimbazafy V, Gaulier JM, Strobel M, Preux PM. Availability and Costs of Antiepileptic Drugs and Quality of Phenobarbital in Vientiane Municipality, Lao PDR. Neuroepidemiology 2007; 28:169-74. [PMID: 17536229 DOI: 10.1159/000103270] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
PURPOSE In developing countries, availability and quality of drugs are critical factors for effective management and control of epilepsy. This study investigated the availability and costs of antiepileptic drugs (AEDs), and the quality of phenobarbital in Vientiane Municipality, Lao PDR. METHODS In March 2004, we enrolled all pharmacies (categories I and II) of four central districts of Vientiane eligible to sell AEDs. Two hundred and eight pharmacies of category III (75.1% of all registered pharmacies) were excluded as the sale of AEDs was not authorized. All pharmacists were interviewed with a standard questionnaire. Whenever phenobarbital was available, a sample was purchased and assayed by liquid chromatography. Phenobarbital was defined as being of correct quality if the active substance average content corresponded to +/-15% of the indicated amount. RESULTS 66 pharmacies were enrolled (13 and 45 of categories I and II, respectively, and 8 hospital pharmacies). Six generics of AEDs were found (phenobarbital, phenytoin, valproic acid, clonazepam, carbamazepine, diazepam) and all pharmacies sold at least 1 AED. The 2 most widely available drugs were diazepam (5 mg) and phenobarbital (100 mg), present in 87.9 and 53.0% of the pharmacies, respectively. All 34 phenobarbital samples examined showed a correct concentration of the active compound. However, the concentration of phenobarbital 100 mg tablets produced in Lao PDR (mean concentration 94.7 mg) was significantly lower (p = 0.005) than the imported equivalent (mean concentration 99.7 mg). The direct drug costs of a yearly treatment with phenobarbital were estimated to be at least 25.2 USD. CONCLUSIONS A variety of AEDs are present. Their availability, particularly of phenobarbital, is restricted to higher-category pharmacies and within those it is rather limited. To meet the costs of AEDs in this setting is a major challenge for people with epilepsy. However, the quality of the available phenobarbital was rather satisfactory.
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Affiliation(s)
- Peter Odermatt
- Institut de la francophonie pour la médecine tropicale, Vientiane, Lao PDR.
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Affiliation(s)
- K Liow
- Via Christi Comprehensive Epilepsy Center, University of Kansas School of Medicine-Wichita, Wichita, KS 67214-3800, USA.
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Abstract
This report addresses: (1) a general update of FDA activity in areas relevant to AED development; (2) an update on issues relevant to the development of AEDs in the pediatric population; and (3) an update on the Agency's approach to the evaluation of AEDs as monotherapy. FDA ACTIONS: Since January 2002, 47 Approval actions for 10 AEDs were issued, but none for a new chemical entity. Nine of the ten Approvable actions taken were relatively minor changes to existing applications. An Approvable letter was issued for Lyrica (pregabalin) for the treatment of post-herpetic neuralgia, painful diabetic neuropathy, and partial seizures in adults. The primary issue to be addressed in the face of post-marketing reports of adverse events is one of causality. The FDA has requested that sponsors search their databases for selected problems under review (e.g., suicidality). PEDIATRICS: The Pediatric Research Equity Act (PREA) and the Best Pharmaceuticals for Children Act (BPCA) require studies in pediatric patients for those indications granted for adults that are relevant for the pediatric population. Current FDA policy asks sponsors to undertake a development program in pediatric patients essentially analogous to that for adults. MONOTHERAPY TRIALS: Establishing the effectiveness of AEDs as monotherapy continues to be desirable, but problematic. Problems include the difficulty of performing monotherapy trials, ethical issues, designation of patients as "newly diagnosed," and endpoints. Historical controls may be acceptable if: (a) there is a consensus that it is essentially impossible to conduct controlled trials designed to demonstrate a difference between treatments; (b) there is an adequate historical database against which the seizure rate seen with the new drug can reasonably be compared; and (c) there is evidence from adequate and well-controlled trials that the treatment is effective as adjunctive therapy. FDA is Agency is reviewing analyses describing historical controls.
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Abstract
PURPOSE Epilepsy is a major public-health problem in Africa. The quality of available drugs is a limiting factor for an adequate management. The aim of this study was to describe the proportion of poor-quality phenobarbital (PB) solid-dosage forms and evaluate the factors associated with its quality in Nouakchott (Mauritania). METHODS A cross-sectional study was carried out within pharmacies, hospitals, and on the parallel market in March 2003. PB samples were bought by a native person and then assayed by a liquid chromatography method. A package was considered to be of good quality if the active-substance average content was between 85 and 115% of the stated content printed on the packet. RESULTS Forty-five pharmaceutical stores were visited, enabling us to collect 146 samples of PB. Three brand names were available in Nouakchott. They originated from France, Morocco, Senegal, and Egypt. Results: A prevalence of 13.7%[95% confidence interval (CI), 8.8-20.0] of poor-quality PB was found. All samples from Morocco were underdosed. The generic active content was satisfactory, but saccharose, an excipient with a potential side effects, was identified. Two factors associated with the good quality of PB have been put forward: tablets manufactured in France and loose packaging as generics conditioned in such a way were of good quality. CONCLUSIONS This study shows that the quality of antiepileptic drugs in Africa is still worrying. The setting up of medicine quality control in Mauritania is legitimate. Considering the good quality of generic PB and its lower cost, this type of medicine should be promoted in this region.
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Affiliation(s)
- Marie-Laure Laroche
- Institute of Neuroepidemiology and Tropical Neurology (EA 3174), Faculty of Medicine, Limoges, France
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Goodwin M. The importance of brand continuity in epilepsy drugs. Nurs Times 2005; 101:26-7. [PMID: 15997944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Drugs are the mainstay of treatment for epilepsy, and are effective for most patients. However, minute differences between generic and branded drugs, and between different brands of the same drug, can affect epilepsy control. It is vital therefore that patients receive the same brand consistently to avoid loss of control.
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Heinzl S. [The "evil" pharmacists]. Med Monatsschr Pharm 2005; 28:185. [PMID: 15960419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
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Jörg Leis H, Windischhofer W, Rechberger GN, Fauler G. Synthesis of [(18)O(2)]valproic acid and its use as an internal standard for the quantitative measurement by gas chromatography-electron ionization mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci 2003; 784:69-75. [PMID: 12504184 DOI: 10.1016/s1570-0232(02)00755-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A specific method for the quantitative determination of valproic acid in human plasma is presented. Valproate was extracted from acidified plasma by hexane extraction and converted to its trimethylsilyl derivative without sample concentration. The derivatives were analyzed without any further purification. Using gas chromatography-electron ionization mass spectrometry, diagnostic useful fragment ions at m/z 201 and 205 were obtained for valproic acid and [(18)O(2)]valproic acid internal standard, respectively. [(18)O(2)]Valproic acid was synthesized from unlabeled valproate by acid-catalyzed exchange reaction in H(2)(18)O. The method was validated in the expected concentration range of a pharmacokinetic study. Thus, calibration graphs were linear within a range of 0.47-120 microgram/ml plasma. Intra-day precision was 2.29% (0.47 microgram/ml), 2.93% (4 microgram/ml), 3.22% (20 microgram/ml) and 4.40% (80 microgram/ml), inter-day variability was found to be 1.49% (0.47 microgram/ml), 3.79% (20 microgram/ml), 2.74% (40 microgram/ml) and 3.03% (80 microgram/ml). Inter-day accuracy showed deviations of 1.94% (0.47 microgram/ml), 0.53% (4 microgram/ml), -0.32% (20 microgram/ml) and 0.06% (80 microgram/ml). The method is rugged and robust and has been applied to the batch analysis of valproate during pharmacokinetic profiling of the drug.
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Affiliation(s)
- Hans Jörg Leis
- University Children's Hospital, Division of Analytical Biochemistry and Mass Spectrometry, Auenbruggerplatz 30, A-8036, Graz, Austria.
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Wilson JF, Watson ID, Williams J, Toseland PA, Thomson AH, Sweeney G, Smith BL, Sandle LN, Ramsey JD, Capps NE. Primary standardization of assays for anticonvulsant drugs: comparison of accuracy and precision. Clin Chem 2002; 48:1963-9. [PMID: 12406982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2023]
Abstract
BACKGROUND The accuracy and precision of methods for the measurement of the anticonvulsants phenytoin, phenobarbital, primidone, carbamazepine, ethosuximide, and valproate in human serum were assessed in 297 laboratories that were participants in the United Kingdom National External Quality Assessment Scheme (UKNEQAS). METHODS We distributed lyophilized, serum-based materials containing low, medium, and high weighed-in concentrations of the drugs. The 297 participating laboratories received the materials on two occasions, 7 months apart. Expected concentrations were determined by gas chromatography or HPLC methods in five laboratories using serum-based NIST reference materials as calibrators. RESULTS In general, bias was consistent across concentrations for a method but often differed in magnitude for different drugs. Bias ranged from -1.9% to 8.6% for phenytoin, -2.7% to 3.1% for phenobarbital, -2.7% to 0.5% for primidone, -8.6% to 0.3% for carbamazepine, -5.6% to 2.0% for ethosuximide, and -7.2% to 0.1% for valproate. Intralaboratory sources of imprecision significantly exceeded interlaboratory sources for many drug/method combinations. The mean CVs for intra- and interlaboratory errors for the different drugs were 6.3-7.8% and 3.3-4.2%, respectively. CONCLUSIONS For these long-established and relatively high-concentration analytes, the closed analytical platforms generally performed no better than open systems or chromatography, where use of calibrators prepared in house predominated. To improve the accuracy of measurements, work is required principally by the manufacturers of immunoassays to ensure minimal calibration error and to eliminate batch-to-batch variability of reagents. Individual laboratories should concentrate on minimizing dispensing errors.
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Affiliation(s)
- John F Wilson
- Department of Pharmacology, Therapeutics & Toxicology, University of Wales College of Medicine, Cardiff CF14 4XN, United Kingdom.
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Abstract
PURPOSE Treatment with sodium valproate (VPA) may be associated with polycystic ovarian syndrome (PCOS) in some women with epilepsy. By comparing hormone profiles in young adults taking VPA or lamotrigine (LTG) as monotherapy, this study aimed to explore whether a pharmacologic effect of VPA could be responsible for this observation. METHODS Hormone profiles in men and women taking VPA (n = 40) or LTG (n = 36) monotherapy for epilepsy were compared. None of the women were receiving hormonal contraception or replacement. Patients gave details of seizure type and frequency, menstrual cycle, and medical and drug history. Body mass index was calculated, and fasting insulin, glucose, cholesterol, triglycerides (TG), high- and low-density lipoproteins, testosterone, dihydroepiandosterone (DHEA), androstenedione, sex hormone-binding globulin (SHBG), free androgen index (FAI), luteinising hormone (LH), follicle-stimulating hormone (FSH), and antiepileptic drug (AED) concentrations were measured. RESULTS There were no differences between treatment groups for both sexes in age and seizure control. Only four obese VPA-treated women were hyperinsulinaemic (p = 0.05); three with abnormal menstrual cycles; one with raised testosterone. Testosterone (p = 0.02), FAI (p = 0.03), and TG (p = 0.02) levels were higher, however, in women taking the drug. Obese patients of both sexes (p = 0.01) and VPA-treated men (p = 0.03) had higher insulin concentrations. CONCLUSIONS VPA therapy may be associated with subclinical elevation in fasting insulin levels. Testosterone and TG levels were higher in VPA-treated women compared with the levels in those taking LTG. However, only a minority of obese females exhibited biochemical characteristics suggestive of PCOS. Biochemical screening may allow women at risk of developing PCOS to avoid VPA.
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Affiliation(s)
- L J Stephen
- Epilepsy Unit, University Department of Medicine and Therapeutics, Western Infirmary, Glasgow, Scotland, UK
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George S, Gill L, Braithwaite RA. Simple high-performance liquid chromatographic method to monitor vigabatrin, and preliminary review of concentrations determined in epileptic patients. Ann Clin Biochem 2000; 37 ( Pt 3):338-42. [PMID: 10817248 DOI: 10.1258/0004563001899249] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A simple and rapid high-performance liquid chromatographic method has been developed for the determination of vigabatrin concentrations in plasma or serum. The assay uses only 100 microL of specimen and has been found to be linear over a concentration range of 1 to 50 mg/L. The limit of detection has been determined as 1 mg/L, and the between-batch coefficient of variation for the two internal quality controls routinely analysed (n = 33) has been found to be less than 5%. There was no evidence of interferences in the assay from other commonly prescribed anti-epileptic drugs. This method has been applied to routine clinical specimens to determine the concentration of vigabatrin in 47 patient specimens over a 12-month period. It was found that only 63% of the male group and 53% of the female group were within the proposed target concentration of 5 to 35 mg/L. In addition, it was found that 26% of the male group and 36% of the female group were found to have concentrations below 5 mg/L, which may indicate lack of compliance and/or lack of therapeutic efficacy of treatment.
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Affiliation(s)
- S George
- Regional Laboratory for Toxicology, City Hospital NHS Teaching Trust, Birmingham, UK.
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Abstract
New antiepileptic drugs have been developed and released for the treatment of chronic focal and secondarily generalized epileptic seizures. The anticonvulsant efficacy of these drugs (vigabatrin, lamotrigine, gabapentin, felbamate, tiagabine, topiramate and oxcarbazepine) does not seem to be superior to that of traditional anticonvulsants. The main advantage of these newly developed drugs is a different spectrum of possible adverse events (i.e. these drugs usually do not induce sedation). Moreover, interactions with traditional anticonvulsants are less common, therefore, comedication with these drugs shows an improved tolerability. The availability of new antiepileptic drugs enables us to establish an individually tailored anticonvulsant strategy for each patient.
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Affiliation(s)
- C E Elger
- Department of Epileptology, University of Bonn, Bonn, Germany
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el Battah A, Beglia S, Alric R. Validation of a quick modeling program generating clearance estimates at steady state for routine therapeutic drug monitoring. Ther Drug Monit 1995; 17:348-55. [PMID: 7482688 DOI: 10.1097/00007691-199508000-00006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Therapeutic drug monitoring (TDM) of chronic treatments is justified for several reasons, including relative over- or underdosage due to variable individual elimination, pharmacokinetic interactions in drug combinations, and noncompliance. In all these circumstances, the prescribing physician is interested in having an estimation of the patient's clearance of the drug, even from one measurement. We compare a validated bayesian program, USC*Pack of Jelliffe, found difficult to use in daily routine, with a "home-made" program. The latter, which is capable of taking data from a clinical database, will generate a graphic simulation of daily plasma drug concentrations together with an estimation of steady-state clearance more rapidly than does USC*Pack. Both programs were run with only one measured plasma level. The patients were 83 children or young adults treated with phenobarbital (PB), carbamazepine (CBZ), and/or Valproic acid (VPA) who were resistant to monotherapy and who were to be sampled two to four times between doses. Drugs were routinely assayed by high-performance liquid chromatography (HPLC). Despite the rough character of Phacile (numeric integration and adjustment of only two of three parameters, without an acknowledged minimization algorithm), the results are comparable to those obtained with USC*Pack for estimating clearance and predicting plasma drug concentrations. Phacile algorithm, although simple, has proven of interest in routine TDM and as an introduction for medical students to the bayesian approach of population pharmacokinetics.
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Affiliation(s)
- A el Battah
- Laboratoire de Pharmacologie Clinique, Centre Hospitalier Universitaire, Montpellier, France
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Abstract
Antiepileptic drug discovery has made enormous progress from the serendipity and screening processes of earlier days to the rational drug development of today. The modern era of research began with the recognition that enhancement of inhibitory processes in the brain might favorably influence the propensity for seizures, gamma-aminobutyric acid (GABA) being the main inhibitory transmitter. Work in this field led to the development of vigabatrin, which inhibits the enzyme responsible for the degradation of GABA. More recently, research has focused on the therapeutic potential of blocking excitatory amino acids--in particular glutamate. Of the three receptors for glutamate, the N-methyl-D-aspartate (NMDA) receptor is considered the one of most interest in epilepsy, and research on a series of competitive NMDA receptor antagonists--especially those that are orally active--is in the forefront of antiepileptic drug development today. A further alternative for diminishing neuronal excitability is to modulate sodium, potassium, or calcium channels. The latter are especially implicated in absence seizures.
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Affiliation(s)
- R J Porter
- Office of the Director, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892
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Nuwer MR, Browne TR, Dodson WE, Dreifuss FE, Engel J, Leppik IE, Mattson RH, Penry J, Treiman DM, Wilder BJ. Generic substitutions for antiepileptic drugs. Neurology 1990; 40:1647-51. [PMID: 2234419 DOI: 10.1212/wnl.40.11.1647] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
- M R Nuwer
- Department of Neurology, University of California
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Assessment: generic substitution for antiepileptic medication. Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology. Neurology 1990; 40:1641-3. [PMID: 2234417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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Davis HL, Falk KJ, Bailey DG. Improved method for the simultaneous determination of phenobarbital, primidone and diphenylhydantoin in patient's serum by gas-liquid chromatography. J Chromatogr A 1975; 107:61-6. [PMID: 1141418 DOI: 10.1016/s0021-9673(00)82747-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A quantitative gas-liquid chromatographic method for the simultaneous determination of phenobarbital, primidone and diphenylhydantoin in human serum is described. A double extraction is employed to improve the removal of interfering substances. The N,N-dimethyl derivatives of the compounds are prepared by "oncolumn" methylation with 50% Methelute. Decomposition of phenobarbital to N-methyl-a-phenylbutyramide was negligible if the contact time with Methelute was less than 10 min. The drugs were stable in serum for at least two weeks. This procedure provides a rapid, sensitive, selective and accurate method for the routine determination of serum concentrations of three of the most commonly prescribed anticonvulsant drugs.
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Goodman LS. Introduction: symposium on laboratory evaluation of antiepileptic drugs. Epilepsia 1969; 10:105-6. [PMID: 5257107 DOI: 10.1111/j.1528-1157.1969.tb03837.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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