A novel flunarizine hydrochloride-loaded organogel for intraocular drug delivery in situ: Design, physicochemical characteristics and inspection.

We developed a safe and efficacious drug delivery system for treatment of brain diseases. A novel in-situ gel system was prepared using soybean oil, stearic acid and N-methyl-2-pyrrolidinone (NMP) (10:1:3, v/w/v). This system had low viscosity as a sol in vitro and turned into a solid or semi-solid gel in situ after administration. The poorly water-soluble drug flunarizine hydrochloride (FNZ) was incorporated into this "organogel" system. Organogel-FNZ was characterized by light microscopy, differential scanning calorimetry (DSC) and rheology. Drug release in vitro was investigated. The initial "burst" effect did not occur in organogel-FNZ, which is different from other gels formed in situ. Pharmacokinetic studies were undertaken in rats using gel administration (14 mg kg-1), intravenous administration (5 mg kg-1) and administration using drops (14 mg kg-1). Organogel-FNZ could reduce the clearance rate and prolong the duration of action, in the plasma and brain tissues of rats. The peak serum concentration, area under the curve and absolute bioavailability of the organogel-FNZ group were higher than those of the intraocular- drops group. Organogel-FNZ is a promising drug-delivery system for treatment of brain diseases by intraocular administration.

A high-throughput LC-MS/MS method for determination of flunarizine in human plasma: Pharmacokinetic study with different doses.

A high-throughput and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the determination of flunarizine in human plasma. Liquid-liquid extraction under acidic conditions was used to extract flunarizine and flunarizine-d8 from 100 µL human plasma. The mean extraction recovery obtained for flunarizine was 98.85% without compromising the sensitivity of the method. The chromatographic separation was performed on Hypersil Gold C18 (50 × 2.1 mm, 3 µm) column using methanol-10 mm ammonium formate, pH 3.0 (90:10, v/v) as the mobile phase. A tandem mass spectrometer (API-5500) equipped with an electrospray ionization source in the positive ion mode was used for detection of flunarizine. Multiple reaction monitoring was selected for quantitation using the transitions, m/z 405.2 → 203.2 for flunarizine and m/z 413.1 → 203.2 for flunarizine-d8. The validated concentration range was established from 0.10 to 100 ng/mL. The accuracy (96.1-103.1%), intra-batch and inter-batch precision (CV ≤ 5.2%) were satisfactory and the drug was stable in human plasma under all tested conditions. The method was used to evaluate the pharmacokinetics of 5 and 10 mg flunarizine tablet formulation in 24 healthy subjects. The pharmacokinetic parameters Cmax and AUC were dose-proportional.

Respuesta a la flunarizina en un preescolar con migraña confusional / Flunarizine response in a pre-school child with confusional migraine

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Estudio comparativo de grupos independientes de pacientes con migraña episódica tratados preventivamente con flunaricina o nadolol / A study to compare independent groups of patients with episodic migraine who were treated preventively with flunarizine or nadolol

Introducción. La flunaricina, con nivel de evidencia A, y el nadolol, con nivel de evidencia C, estarían indicados como tratamiento preventivo de la migraña. No existen estudios previos que comparen la efectividad de ambos fármacos. Objetivo. Comparar parámetros de efectividad en grupos independientes de pacientes tratados preventivamente con uno de los fármacos del estudio a los que se aplicó el mismo protocolo. Pacientes y métodos. Se seleccionó a pacientes con migraña episódica (criterios de la Sociedad Internacional de Cefaleas del 2004) que se habían sometido a tratamiento preventivo por primera vez, con flunaricina (5 mg/día) o nadolol (20-40 mg/día). Se analizaron las variables principales de efectividad (reducción del número de crisis al cuarto mes de tratamiento y tasa de respondedores). Resultados. Se incluyó a 227 pacientes con intención de recibir tratamiento: 155 con flunaricina (80,5% mujeres; edad media: 38,3 ± 12,1 años) y 72 con nadolol (63,8% mujeres; edad media: 37,1 ± 12,0 años). La media de crisis en el mes previo al tratamiento fue de 6,09 ± 2,6 en el grupo de la flunaricina y de 5,1 ± 1,7 en el grupo del nadolol (p = 0,0079); la media de crisis al cuarto mes de tratamiento fue de 2,61 ± 2,4 en el grupo de la flunaricina y de 2,77 ± 2,4 en el grupo del nadolol (p = NS). Porcentaje de reducción de migrañas: 55,2% con flunaricina y 50,4% con nadolol (p = NS). La tasa de respondedores fue del 69% con flunaricina y del 67% con nadolol (p = NS). La tasa de respuesta excelente (reducción mayor o igual al 75% de las crisis) fue del 52,2% con flunaricina y del 36,1% con nadolol (p = 0,0077). Porcentaje de efectos adversos: 48,3% con flunaricina frente a 25% con nadolol (p = 0,0009). La tasa de satisfacción fue del 68%, similar en ambos grupos. Conclusión. Tanto la flunaricina como el nadolol mostraron ser efectivos en el tratamiento preventivo de la migraña episódica. La flunaricina se utilizó con mayor frecuencia en nuestro medio y fue peor tolerada (AU)

Introduction. Flunarizine, with level of evidence A, and nadolol, with evidence level C, would be indicated as preventive treatment of migraine. Yet, no previous studies have been conducted to compare the effectiveness of the two drugs. Aim. To compare the effectiveness parameters in independent groups of patients treated preventively with one of the pharmaceuticals from the study, the same protocol being applied in both cases. Patients and methods. The subjects selected for the study were patients with episodic migraine (according to 2004 International Headache Society criteria) who had undergone preventive treatment for the first time, with flunarizine (5 mg/day) or nadolol (20-40 mg/day). The main effectiveness variables (reduction in the number of seizures at four months of treatment and responder rates) were analysed. Results. The study included 227 patients who intended to receive treatment: 155 with flunarizine (80.5% females; mean age: 38.3 ± 12.1 years) and 72 with nadolol (63.8% females; mean age: 37.1 ± 12.0 years). The mean number of seizures prior to treatment was 6.09 ± 2.6 in the flunarizine group and 5.1 ± 1.7 in the nadolol group (p = 0.0079); at four months of treatment it was 2.61 ± 2.4 in the flunarizine group and 2.77 ± 2.4 in the nadolol group (p = NS). Percentage of reduction of migraines: 55.2% with flunarizine and 50.4% with nadolol (p = NS). The responder rate was 69% with flunarizine and 67% with nadolol (p = NS). The excellent response rate (reduction in the number of seizures by 75% or more) was 52.2% with flunarizine and 36.1% with nadolol (p = 0.0077). Percentage of adverse side effects: 48.3% with flunarizine and 25% with nadolol (p = 0.0009). The satisfaction rate was similar in both groups, 68%. Conclusions. Both flunarizine and nadolol proved to be effective in the preventive treatment of episodic migraine. Flunarizine is used more often in our milieu and was less well tolerated (AU)

Is flunarizine a long-acting oral atypical antipsychotic? A randomized clinical trial versus haloperidol for the treatment of schizophrenia.

BACKGROUND: Flunarizine is known as a nonspecific calcium channel blocker that has been used for decades for the treatment of migraine, vertigo, and cognitive deficits related to cerebrovascular disorders. Flunarizine also has dopamine D2 receptor blocking properties and was effective in animal models of predictive validity for antipsychotics. However, its clinical antipsychotic efficacy has never been investigated. OBJECTIVE: To evaluate the therapeutic efficacy and tolerability of flunarizine compared to haloperidol in outpatients with stable and chronic DSM-IV-defined schizophrenia and schizoaffective disorder. METHOD: Seventy patients from 2 centers were randomly assigned and participated in a double-blind, parallel-group, flexible-dose study comparing flunarizine (10-50 mg/day) and haloperidol (2.5-12.5 mg/day) for 12 weeks. Patients were assessed with the Positive and Negative Syndrome Scale (PANSS), the Clinical Global Impressions-Improvement (CGI-I) scale, the Extrapyramidal Symptom Rating Scale (ESRS), a battery for cognitive performance, and laboratory examinations. The study was conducted from September 2004 to May 2007. RESULTS: Mean doses at endpoint were 29.7 mg/day for flunarizine and 6.4 mg/day for haloperidol. Both groups showed significant symptom improvement during the study, with a reduction of 21% in the flunarizine group and 19% in the haloperidol group in PANSS total scores (p < .05). There were no significant differences in PANSS overall score and all subscales, CGI-I score, or cognitive performance. Dropout rates, ESRS scores, and prolactin levels were not different between groups, but significantly more patients reported emergence of akathisia in the haloperidol group (p = .04), and weight gain was significantly higher with flunarizine (1.2 kg) than with haloperidol (-0.8 kg) (p < .05). CONCLUSION: This is the first study evaluating the antipsychotic properties of flunarizine, which showed good efficacy and tolerability for the treatment of schizophrenia, with a possible atypical profile. Its unique pharmacokinetic profile as an oral drug with long half-life (2-7 weeks), low cost, and low induction of extrapyramidal symptoms warrants further investigation, particularly in psychiatric patients with low adherence to treatment.

Formulation, preparation and evaluation of flunarizine-loaded lipid microspheres.

The aim of this study was to investigate the feasibility of preparing flunarizine-loaded lipid microspheres. Lipid microspheres (LMs) are excellent drug carriers for drug delivery systems (DDS) and are relatively stable and easily mass-produced. They have no particular adverse effects. LMs have been widely studied as drug carriers for water-soluble drugs, lipid-soluble drugs and inadequately soluble (in water or in lipid) drugs, in that they have a lipid layer, a water layer and an emulsifier layer. Flunarizine (FZ), a poorly water-soluble drug, was incorporated in lipid microspheres to reduce side effects by avoiding the use of supplementary agents, compared with solution injection. After investigation, the final formulation was as follows: 10% oil phase (long-chain triglyceride (LCT); medium-chain fatty acid (MCT) = 50:50); 1.2% egg lecithin; 0.2% Tween-80; 2.5% glycerin; 0.3% dl-alpha-tocopherol; 0.02% EDTA; 0.03% sodium oleate; 0.1% FZ and double-distilled water to give a total volume of 100 mL. Homogenization was the main method of preparation and the best conditions were a temperature of 40 degrees C, a pressure of 700-800 bar and a suitable cycle frequency of about 10. The particle size distribution, zeta-potential and entrapment efficacy were found to be 198.7+/-54.0 nm, -26.4 mV and 96.2%, respectively. Its concentration in the preparation was 1.0 mg mL(-1). The lipid microspheres were stable during storage at 4 degrees C, 25 degrees C and 37 degrees C for 3 months. Pharmacokinetic studies were performed in rats using a dose of 1.0 mg kg(-1). The pharmacokinetic parameters were as follows: AUC(0-t) 6.13 mug.h mL(-1), t(1/2) 5.32 h and Ke 0.16 L h(-1). The preparation data fitted a two-compartment model estimated by using 3p87 analysis software. From the observed data, FZ encapsulated in LMs did not significantly alter the pharmacokinetic characteristic compared with the FZ solution injection and did not produce a delayed release effect, when it was released in-vivo in rats. However, the availability of the drug was increased. These results suggested that this LM system is a promising option for the preparation of the liquid form of FZ for intravenous administration.

Uso de antagonistas del calcio en el tratamiento del síndrome uretral en las mujeres con urgencia e incontinencia urinaria / Calcium antagonist in the urethral syndrome of the woman with incontinence and urgence

Objetivo: Se evalúa la acción de los antagonistas del calcio en el Síndrome Uretral de la mujer (incontinencia, urgencia, disuria). Pacientes y Metodos: En 60 pacientes de sexo femenino que acudieron con Síndrome Uretral. Se utilizo la Cinarizina en 20 pacientes, y la Flunarizina en 20 pacientes. Y en 20 pacientes se utilizó placebo. Resultados: En las pacientes que recibieron Flunarizina como Cinarizina se observo una reducción de la incontinencia de orina, de la urgencia, y de la disuria, la micción fue mas prolongada y más fácil, el número de las micciones se redujo al día, comparados con las pacientes tratadas con placebo. Conclusiones: Los antagonistas del calcio pueden ser útiles en aquellas pacientes con síndrome uretral en especial en las mujeres mayores

Objective: The action of the antagonists of the calcium was evaluated in the Urethral Syndrome of the woman (incontinence, urgency, disury). Patient and Methods: In 60 female’s patients that went for urethral syndrome. I used the Cinarizina in 20 patients, and the Flunarizina in 20 patients. And in 20 patients were used placebo. Results: In the patients that used Flunarizina and Cinarizina were observed a reduction of the urine incontinence, of the urgency, and the disury, the micturition was lingering and easy, the number of the micturitions decreased by the morning, compared with the patients that used placebo. Conclusions: The antagonists of the calcium can be useful in those patients with urethral syndrome especially the biggest women

Atypical antipsychotic profile of flunarizine in animal models.

RATIONALE: Flunarizine is known as a calcium channel blocker commonly used in many countries to treat migraine and vertigo. Parkinsonism has been described as one of its side-effects in the elderly, which is in agreement with its recently characterized moderate D2 receptor antagonism. OBJECTIVES: To perform a pre-clinical evaluation of flunarizine as a potential antipsychotic. METHODS: We evaluated the action of orally administered flunarizine in mice against hyperlocomotion induced by amphetamine and dizocilpine (MK-801) as pharmacological models of schizophrenia, induction of catalepsy as a measure for extrapyramidal symptoms and impairment induced by dizocilpine on the delayed alternation task for working memory. RESULTS: Flunarizine robustly inhibited hyperlocomotion induced by both amphetamine and dizocilpine at doses that do not reduce spontaneous locomotion (3-30 mg/kg). Mild catalepsy was observed at 30 mg/kg, being more pronounced at 50 mg/kg and 100 mg/kg. Flunarizine (30 mg/kg) improved dizocilpine-induced impairment on the delayed alternation test. CONCLUSIONS: These results suggest a profile comparable to atypical antipsychotics. The low cost, good tolerability and long half-life (over 2 weeks) of flunarizine are possible advantages for its use as an atypical antipsychotic. These results warrant clinical trials with flunarizine for the treatment of schizophrenia.

Matrix-assisted laser desorption/ionisation mass spectrometry in the study of polycondensation of Ti(OBun)4 in the presence of Si(OEt)4.

The hydrolysis-polycondensation behaviour of alcoholic solutions containing Si(OEt)4 and Ti(OBun)4, in different molar ratios (Si/Ti = 10-0.2), was analysed by laser desorption/ionisation (LDI) and matrix-assisted laser desorption/ionisation (MALDI) mass spectrometry. The solutions were prepared using operating conditions usually employed in the sol-gel synthesis of SiO2-TiO2 materials. In accord with the well-known procedures for controlling the different chemical reactivities of the alkoxides, the pre-hydrolysis of the slower reacting silicon ethoxide and the chelation by acetylacetone of the faster reacting titanium butoxide were performed before mass spectrometric analysis. While LDI-MS did not provide evidence for the presence of mixed Si-Ti species in samples obtained from these reactions, MALDI-MS of samples diluted with chloroform and using 2,5-dihydroxybenzoic acid (DHB) as matrix led to detection of various oligomers with different contents of Si and Ti atoms. The results suggest that the formation of Si-Ti mixed oligomers seems to be the favoured process, especially for solutions in which one of the two components is diluted.

Pharmacokinetic profile of topical flunarizine in rabbit eye and plasma.

The purpose of this study was to determine the aqueous humor, cornea, iris-ciliary body, retina and plasma levels and pharmacokinetics of a new topical formulation containing 0.05% flunarizine upon single drop application. Albino rabbits were used and tissue samples were collected at 15, 30, 60, 120 and 240 min after instillation. Drug concentrations in ocular tissues and plasma were measured by gas chromatography assay. After single dose application peak levels of drug were achieved at 15 min in cornea and at 30 min in aqueous humor, iris-ciliary body and retina. Unilateral topical flunarizine caused a significant reduction of intraocular pressure in rabbits. The pharmacokinetic profile showed a good ocular bioavailability of the drug providing that the new topical formulation containing 0.05% flunarizine reach the target tissues at effective concentrations and therefore may be use in the treatment of glaucoma.

Determination of flunarizine in rat brain by liquid chromatography-electrospray mass spectrometry.

A rapid liquid chromatography-electrospray mass spectrometry (LC-ES-MS) assay for the determination of flunarizine (FZ) in rat brain has been developed. A C18 column and an isocratic elution were employed for the separation. Using post-column split, 64% of the eluent was introduced into the ES-MS system for detection. The [M+H]+ (m/z 406) and a fragmented ion (m/z 203) were detected using selected ion monitoring. The linear range of this assay was good, ranging from 0.05 to 5 microM (r2=0.99). The intra- and inter-day precisions showed relative standard deviations ranging from 1.4% to 2.0% and 1.3% to 2.9%, respectively. The application of this newly developed method was demonstrated by examining the pharmacokinetics of FZ in rat brain.

Low-dose flunarizine does not affect short-term fetal circulatory responses to acute asphyxia in sheep near term.

Asphyxia is one of the major causes of perinatal brain damage and neuronal cell loss, which may result in psychomotor deficits during later development. It has been shown previously that the immature brain can be protected from ischemic injury by flunarizine, a class IV calcium antagonist. However, cardiovascular side-effects of flunarizine, when applied at the dosages used in those studies, have been reported. Recently, the present authors were able to demonstrate that even by injecting flunarizine at a far lower dosage (1 mg kg-1 estimated bodyweight) neuronal cell damage, caused by occlusion of both carotid arteries for 30 min, can be reduced in fetal sheep near term. The aim of the present study was, therefore, to examine whether low-dose flunarizine affects fetal cardiovascular responses to acute asphyxia in sheep near term. Ten fetal sheep were chronically instrumented at a mean gestational age of 132 +/- 1 days (term is at 147 days). Fetuses from the study group received a bolus injection of flunarizine (1 mg kg-1 estimated fetal weight) 60 min before asphyxia, whereas the solvent was administered to the fetuses from the control group. Organ blood flows, physiological variables and plasma concentrations of catecholamines were measured before, during and after a single occlusion of uterine blood flow for 2 min (i.e. at 0, 1, 2, 3, 4, and 30 min). Before asphyxia, the distribution of combined ventricular output and physiological variables, as well as concentrations of catecholamines, in fetuses from the control group were in the normal range for chronically prepared fetal sheep near term. During acute asphyxia there was a redistribution of cardiac output towards the central organs accompanied by a pronounced bradycardia and a rapid increase in arterial blood pressure. After asphyxia circulatory centralization did not resolve quite as rapidly as it developed, but was almost completely recovered at 30 min after the insult. There were nearly no differences in the time course of physiological and cardiovascular variables measured before, during and after acute intrauterine asphyxia between the control and study groups. From the present study it was concluded that low-dose flunarizine does not affect short-term fetal circulatory responses to acute asphyxia in sheep near term.

A limited sampling method for the estimation of flunarizine area under the curve (AUC) and maximum plasma concentration (Cmax).

A limited sampling model has been developed for flunarizine following a 30 mg oral dose in epileptic patients who were receiving phenytoin or carbamazepine or both, to estimate the area under the curve (AUC) and maximum plasma concentration (Cmax). The model was developed using training data sets from 30, 20, 15, or 10 patients at one or two time points. The equations describing the models for AUC using two time points (3 and 24h) and Cmax for the training data set of 30 subjects were AUCpredicted = 11.1 C3h + 121.4 C24h - 157 (r = 0.80) Cmax(predicted) = 0.036 AUC + 42.9 (r = 0.74) The model was validated on 64 patients who received flunarizine orally. The model provided reasonably good estimates for both AUC and Cmax. The mean predicted AUC of flunarizine was 1230 +/- 717 ng h mL-1, whereas the observed AUC was 1203 +/- 900 ng h mL-1. The bias of the prediction was 2% and precision was 28%. The mean predicted Cmax of flunarizine was 86 +/- 32 ng mL-1 as compared to an observed mean Cmax of 90 +/- 42 ng mL-1. The bias and precision of the prediction were 4% and 24%, respectively. The method described here may be used to estimate AUC and Cmax for flunarizine without detailed pharmacokinetic studies.

Espectro de acción antiepiléptica de la DL-4-hidroxi, 4-etil,4-fenil butiramida y sus homólogos inferiores / Profile of the antiepileptic action of DL-4-hydroxy, 4-ethyl, 4-phenyl butiramide and its inferior homologues

Se estudio la actividad farmacológica en animales de una serie nueva de compuestos anticonvulsionantes, la DL-4-hidroxil, 4-etil, 4-fenil butiramida (HEPB) y sus homólogos inferiores propionamida (HEPP) y acetamida (HEPA). La neurotoxidad fue determinada con un rotarod y se indujeron cuadros convulsivos con electrochoque supramáximo (MES), pentilentetrazol (TSC), estricnina (STR) y picrotoxina (PIC). HEPP es menos neurotóxica que HEPB y HEPA y altera el comportamiento de los ratones solamente a dosis altas. Los tres compuestos presentaron un amplio espectro de acción anticonvulsionante. Ellos son muy potentes para inhibir cuadros convulsivos inducidos con 4-AP, BIC, TSC y PTZ en dosis no tóxicas administradas ip, pero son inefectivas contra convulsiones inducidas con pic y STR. Los índices terapéuticos (IT = DT 50/D 50) fueron más elevados para HEPP. En consecuencia los resultados indican que los tres compuestos probados pueden servir para el tratamiento de convulsiones generalizadas tipo ausencias. Puesto que HEPP es el compuesto menos neurotóxico se ha seleccionado para los estudios toxicológicos y neuroquímicos

Possible pharmacokinetic and pharmacodynamic factors affecting parkinsonism inducement by cinnarizine and flunarizine.

Potentialities of cinnarizine [1-(diphenylmethyl)-4-(3-phenyl-2-propenyl)piperazine, CZ] and its fluorine derivative flunarizine [1-[bis(4-fluorophenyl)-methyl]-4-(3-phenyl-2-propenyl)piperazine, FZ] to induce parkinsonism as an adverse effect were evaluated pharmacokinetically and pharmacodynamically in rats. In multiple-dose experiments, CZ or FZ was given to rats at a daily dose of 20 mumol/kg for 1, 5, 10, 15, and 30 days, and CZ, FZ, and the ring-hydroxylated metabolites of their cinnamyl moiety [1-(diphenylmethyl)-4-[3-(4'-hydroxyphenyl)-2-propenyl]piperazine, C-2 and 1-[bis(4-fluorophenyl)methyl]-4-[3-(4'- hydroxyphenyl)propenyl]piperazine, F-2] in the plasma and striatum were determined 24 hr after the final dose. Plasma and striatum concentrations of the above compounds except for FZ reached steady state after 10 doses, but their concentrations of FZ continued to increase throughout the experiments. The concentrations obtained after the 30 doses were in the order of FZ > F-2 > CZ > C-2 for the plasma and of F-2 > FZ > CZ > C-2 for the striatum. The ratios of striatum to plasma concentrations of C-2 and F-2 were 2.4 and 3 times higher than those of the parent drugs. Binding affinities of CZ, FZ, and their 10 metabolites for rat striatal dopamine D-2 receptors (D2-R) were assessed by competitive radioligand-binding studies using [3H]-N-[(2RS,3RS)-1-benzyl-2-methyl-3-pyrrolidinyl]-5-chloro-2-met hoxy- 4-methylamino-benzamide ([3H]-YM-09151-2). The IC50s calculated from their Ki values were in the order of F-2 < C-2 < FZ < CZ < C-4 << F-1, indicating that C-2 and F-2 exhibit higher affinities for D2-R than the parent drugs, whereas affinities of other metabolites were 1 to 2 orders of magnitude less than those of C-2 and F-2. These results suggest some important roles of C-2 and F-2 in the development of parkinsonism as active metabolites during chronic medication with CZ and FZ, respectively.

Flunarizine of limited value in children with intractable epilepsy.

Fourteen ambulatory children and adolescents with intractable epilepsy were studied in an open phase II study to investigate the pharmacokinetics and pharmacodynamics of flunarizine as an add-on treatment. Flunarizine was given in increasing doses starting with 0.1-0.3 mg/kg/day until effect was observed or a steady-state plasma concentration of 50-60 ng/ml was reached. Treatment was continued for 3 months at steady state. Pharmacokinetics were determined during the immediate posttreatment period. Positive antiepileptic effect (> or = 50% reduction in seizure frequency) was observed in 4 of 14 patients (29%; 95% CI: 52-5). Independently of antiepileptic effect, 10 of 14 parents (71.4%; 95% CI: 95-48) observed positive cognitive effects. In all patients treatment was withdrawn due to either lack of effect or weight gain. Flunarizine was rapidly absorbed; mean time of peak concentration (Tmax) was 2.7 hours (range: 1-8). The mean terminal half-life was 23.2 days (range: 7-48), the total plasma clearance of flunarizine per fraction of the dose absorbed (CLp/F) was 0.28 ml/min/kg (range: 0.07-042), and the volume of distribution of flunarizine per fraction of the dose absorbed (Vd/F) was 187 L/kg (range: 99-348). We conclude that flunarizine (0.1-0.3 mg/kg/day) seems to be of limited antiepileptic value in children with intractable epilepsy. The pharmacokinetic profile of flunarizine complicates its clinical use.

Flunarizine for treatment of partial seizures: results of a concentration-controlled trial.

The National Institutes of Health sponsored a randomized, double-blind, multicenter, placebo-controlled trial of flunarizine (FNR) in epileptic patients receiving concomitant phenytoin (PHT) or carbamazepine (CBZ). Because of FNR's long half-life (up to 7 weeks), a parallel rather than crossover design was used. Each patient received an individualized loading dose and maintenance dosage targeted at a 60-ng/ml plasma FNR concentration. Of 93 patients randomized, 92 provided seizure data for the full 25-week treatment period; one placebo-treated patient dropped out for personal reasons. Fifty-four patients received CBZ only, nine received PHT only, and 30 received both CBZ and PHT. Eighty-seven patients had a history of complex partial seizures, and 60 had secondarily generalized seizures. Eight patients discontinued FNR prematurely, all because of adverse neurologic or psychiatric signs or symptoms; depression was the specific cause in three cases. Calculated maintenance dosages, based on single-dose pharmacokinetic profiles, ranged from 7 to 138 mg/day (mean, 40 mg/day). Plasma FNR concentrations generally exceeded the target, with the highest concentrations observed immediately after loading; excluding the first three treatment weeks and all concentrations after a FNR dosage change, the median plasma FNR concentration was 71.7 ng/ml. The percent reduction from baseline seizure rate was statistically greater (p = 0.002) in the FNR-treated group (mean, 24.4%) than in the placebo-treated group (mean, 5.7%).

New anticonvulsant drugs. Focus on flunarizine, fosphenytoin, midazolam and stiripentol.

In the past decade, several new antiepileptic drugs have been tested. Most recently, 5 new antiepileptic drugs have been launched onto European and US markets. These include vigabatrin, oxcarbazepine and lamotrigine in Europe, and felbamate and gabapentin in the US. In addition to these, 3 additional drugs are in the clinical investigational stage: flunarizine, fosphenytoin and stiripentol. A fourth agent is midazolam, which was originally introduced in 1986, but recently has shown effectiveness in the treatment of status epilepticus. Flunarizine is a selective calcium channel blocker that has shown anticonvulsant properties in both animal and human studies. It is a long-acting anticonvulsant that clinical studies have shown to have effects similar to those of phenytoin and carbamazepine in the treatment of partial, complex partial and generalised seizures. Fosphenytoin was developed to eliminate the poor aqueous solubility and irritant properties of intravenous phenytoin. It is rapidly converted to phenytoin after intravenous or intramuscular administration. In clinical studies, this prodrug showed minimal evidence of adverse events and no serious cardiovascular or respiratory adverse reactions. It may have a clear advantage over the present parenteral formulation of phenytoin. Midazolam is a benzodiazepine that is more potent than diazepam as a sedative, muscle relaxant and in its influence on electroencephalographic measures. It has been shown to be an effective treatment for refractory seizures in status epilepticus. Stiripentol has anticonvulsant properties as well as the ability to inhibit the cytochrome P450 system. There are significant metabolic drug interactions between stiripentol and phenytoin, carbamazepine and phenobarbital (phenobarbitone). Stiripentol has been studied in patients with partial seizures, refractory epilepsy and refractory absence seizures with some efficacious results.

Increasing plasma concentration tolerability study of flunarizine in comedicated epileptic patients.

Twelve patients with intractable partial seizures [4 receiving carbamazepine (CBZ), 4 phenytoin (PHT), and 4 both] entered a study of the tolerability of flunarizine (FNR) at specified plasma concentrations. After an 8-week baseline period, a single-dose pharmacokinetic study was performed for each patient to calculate a loading dose and maintenance dosage necessary to achieve a target plasma FNR concentration of 30 ng/ml. The first 8 patients received the loading dose (as divided doses) during a 1-week hospitalization and the maintenance dosage for the ensuing 8 weeks. These patients proceeded to treatment periods with target concentrations of 60 and then 120 ng/ml, using doses based on an assumed linear relation between dose and plasma concentration. The last 4 patients were studied only at the 120- ng/ml target level. Results indicated that this procedure successfully approximated target levels of 30 and 60 ng/ml, but observed concentrations in the last period exceeded the 120-ng/ml target level and continued to increase with time, often necessitating a dosage reduction owing to intolerability. Calculated doses for a given target concentration varied by a factor of 12. The most frequently reported adverse experiences were sedation and increased fatigue; reports of dizziness, headache, and lethargy were also common. Based on this study, a target concentration of at least 60 but < 120 ng/ml is recommended for a controlled clinical trial of the antiepileptic efficacy of FNR.

Comparative pharmacokinetics of the newer antiepileptic drugs.

During the past few years a major increase has taken place in the number of drugs which have become available in the antiepileptic arsenal. In fact, 3 new antiepileptic drugs, vigabatrin, oxcarbazepine and lamotrigine, were recently approved in several European countries. Two other drugs, felbamate and gabapentin, are expected to be approved in the US in the near future. This review comparatively evaluates the pharmacokinetics of the following 10 new antiepileptic drugs: felbamate, flunarizine, gabapentin, lamotrigine, oxcarbazepine, remacemide, stiripentol, tiagabine, topiramate and vigabatrin. Three of the new drugs, gabapentin, topiramate and vigabatrin, are more promising on the basis of their pharmacokinetic features. They are well absorbed, excreted mainly unchanged in the urine, and are not susceptible to enzyme induction or inhibition. Their drug interaction potential appears to be minimal. About 50% of felbamate is excreted unchanged, with the rest eliminated by metabolism. The remaining drugs are eliminated by metabolic processes such as glucuronidation (lamotrigine), deglycine formation (remacemide) or oxidative metabolism (flunarizine and stiripentol). Oxcarbazepine and remacemide have high hepatic clearance and are biotransformed to hydroxy and deglycine metabolites, respectively, with the activity of their metabolites contributing to the antiepileptic activity of the parent drug after oral administration, despite high first-pass effect metabolism. Gabapentin and oxcarbazepine do not behave pharmacokinetically as their original design intended. Gabapentin is not effective as a chemical drug delivery system for gamma-aminobutyric acid (GABA), and oxcarbazepine serves as a prodrug to its hydroxy metabolite, but does not act as a drug on its own. Nevertheless, these 2 agents demonstrate efficacy in extensive preclinical and clinical trials. Although the pharmacokinetics features of these drugs are important, these features are secondary to their pharmacodynamic properties--i.e. to the requirement that new antiepileptic drugs have to have proven clinical efficacy and safety in epileptic patients.