Control of epilepsy partialis continuans with intravenous nimodipine. Report of two cases

Reduction of human neocortical and guinea pig CA1-neuron A-type currents by organic calcium channel blockers

In epilepsy models, organic calcium antagonists regularly induce a transient activity increase before suppression of epileptiform discharges. This action was speculated to be mediated by a modulation of potassium currents. Since A-type currents potently regulate neuronal excitability, their modulation by calcium channel blockers was investigated in acutely isolated human neocortical temporal lobe neurons and CA1 neurons of guinea pigs using the whole-cell voltage-clamp technique. In human neurons, 40 microM nifedipine caused an amplitude reduction by 28% at a command potential of -6 mV and produced a biexponential, markedly accelerated current inactivation with time constants of 8.4 +/- 1.1 ms (n = 6) and 62.9 +/- 6.4 ms (n = 5). The time constant under control conditions was 50.1 +/- 8.5 ms (n = 6). Verapamil (40 microM) did not affect the current amplitude, but accelerated the monoexponential current inactivation from 40.2 +/- 7.1 ms to 13.3 +/- 0.8 ms (n = 9). Accordingly, verapamil accelerated the inactivation from 42.3 +/- 5.9 ms to 15.0 +/- 1.3 ms (n = 11) in guinea pig CA1 neurons, without affecting the current amplitude. In this preparation, it was shown that the two enantiomers of verapamil do not differ in their actions. The results show that the A-type current in human neocortical and in guinea pig hippocampal neurons is reduced by organic calcium channel blockers.

Effects of nifedipine on rhythmic synchronous activity of human neocortical slices

The antiepileptic effect of the dihydropyridine calcium channel blocker nifedipine was tested in neocortical slice preparations (n=27) from patients ranging in age from four to 46 years (mean=25) who underwent surgery for the treatment of intractable epilepsy. Epileptiform events consisted of spontaneously occurring rhythmic sharp waves as well as of untriggered epileptiform field potentials induced by omission of Mg(2+) from the superfusate, or epileptiform field potentials elicited by application of bicuculline and triggered by single electrical stimuli. (1) Spontaneous rhythmic sharp waves (n=6): with nifedipine (40micromol/l), the repetition rate was decreased down to 30% of initial value, whereas the area under the field potential remained nearly unchanged. (2) Untriggered low Mg(2+) epileptiform field potentials (n=6): with nifedipine (40micromol/l) the area under the field potentials was reduced while the action on the repetition rate was ambiguous. (3) Triggered bicuculline epileptiform field potentials (n=15): with nifedipine (40micromol/l; n=4), no antiepileptic effect was found. There was, however, a marked increase in the area under the epileptiform field potentials. The area under the field potentials was reduced only at a dosage of 60micromol/l (n=11). This effect was stronger when nifedipine was applied with a K(+) concentration raised from 4 to 8mmol/l. The results show that the calcium channel blocker nifedipine is able to reduce differential epileptiform discharges in human neocortical tissue. These observations are in line with previous findings, suggesting that calcium flux into neurons is involved in epileptogenesis. The present results therefore support the idea that some organic calcium antagonists may be useful in human epilepsy therapy, although the etiology of epileptic seizures seems to be a critical factor for the efficacy of the drug.

Epilepsia partialis continua: clinical and electrophysiological features of adult patients

In this study we reviewed the clinical, electrophysiological and neuroimaging data of 21 patients with epilepsia partialis continua (EPC), which is a rare form of epilepsy with focal motor seizures persisting hours to years. We found infections, cerebrovascular events and tumors as the most common causes of EPC in adults. SSPE was also shown as a cause of EPC. EPC in SSPE patients was resistant to therapies and persisted more than 1 year. EPC is usually a predictor of poor outcome and 29% of patients died after EPC in this study. As prognosis is usually bad and as response to treatment is poor in patients who had EPC, early diagnosis and treatment of the underlying cause is important. Although the most common etiologies are infections, cerebrovascular events and tumors, if EPC persists several months SSPE should be kept in mind as a rare cause of EPC. MRI should be repeated in chronic cases to show dysplastic cortex, which was shown in 1 patient in this study.

The influence of nimodipine, nicardipine and amlodipine on the brain free fatty acid level in rats with penicillin-induced seizures

1. The aim of this study was to investigate the effects of the calcium channel blockers, nimodipine, nicardipine and amlodipine, on the brain free fatty acid (FFA) level in rats with chemically-induced seizures. 2. The study was carried out on Hannover-Wistar rats. Animals were anesthetized and placed in a stereotaxic apparatus. Each of them received an injection of penicillin (5000 IU/5 microliters) into the left lateral ventricle (i.c.v.). Various doses (1, 3, 10 or 30 mg/kg) of nimodipine, nicardipine or amlodipine had been injected i.p. 30 min before the penicillin application. The rats were decapitated 5 min after the occurrence of epileptic seizures. FFAs were quantified by gas chromatography using the internal standard method. 3. The results demonstrate that i.c.v. injection of penicillin was associated with significant increase in the brain FFA concentration. Tested doses of nicardipine and amlodipine did not influence the increase of the brain free palmitic, stearic, oleic and arachidonic acid level while nimodipine prevented the accumulation of free palmitic, oleic and arachidonic acid in rats with penicillin-induced seizures. Statistically insignificant decrease of steric acid was observed in animals pretreated with nimodipine. 4. It maybe assumed that the brain FFA accumulation caused by i.c.v. penicillin administration is not predominantly associated with a disturbance in calcium homeostasis via L-type voltage-sensitive calcium channels, but by some other membrane and/or intracellular mechanisms.

Nimodipine monotherapy and carbamazepine augmentation in patients with refractory recurrent affective illness

Of 30 patients with treatment-refractory affective illness, 10 showed a moderate to marked response to blind nimodipine monotherapy compared with placebo on the Clinical Global Impressions Scale. Fourteen inadequately responsive patients (3 unipolar [UP], 11 bipolar [BP]) were treated with the blind addition of carbamazepine. Carbamazepine augmentation of nimodipine converted four (29%) of the partial responders to more robust responders. Patients who showed an excellent response to the nimodipine-carbamazepine combination included individual patients with patterns of rapid cycling, ultradian cycling, UP recurrent brief depression, and one with BP type II depression. When verapamil was blindly substituted for nimodipine, two BP patients failed to maintain improvement but responded again to nimodipine and remained well with a blind transition to another dihydropyridine L-type calcium channel blocker (CCB), isradipine. Mechanistic implications of the response to the dihydropyridine L-type CCB nimodipine alone and in combination with carbamazepine are discussed.

Nimodipine as an add-on therapy for intractable epilepsy

OBJECTIVE

To analyze the effect of nimodipine in patients with intractable epilepsy.

DESIGN

We conducted a double-blind placebo-controlled crossover study in 95 patients.

MATERIAL AND METHODS

The dihydropyridine calcium antagonist nimodipine was used as add-on therapy (60 mg four times a day) in a 1-year placebo-controlled crossover study in 71 patients with localization-related epilepsy and 24 with generalized seizure disorders. Of the 95 patients, 81 were receiving two or more antiepileptic drugs. Patients diaries were used to record the number of seizures and any side effects.

RESULTS

Nimodipine seemed to be well tolerated during the study; only two patients were unable to complete the study because of probable adverse effects. The trial demonstrated no significant crossover effect and no significant effect of nimodipine on either the mean or the median number of seizures or seizure days. The peak median serum nimodipine level was less than 5 ng/mL in the 78 patients who completed the study.

CONCLUSION

This clinical trial found no beneficial effect with use of nimodipine as add-on therapy for intractable epilepsy. Potential reasons for the absence of efficacy of nimodipine may be the inclusion of patients with very refractory seizure disorders or the relatively low serum nimodipine concentrations related to the pharmacokinetic effect of concurrent antiepileptic medication.

Nimodipine. Potential for drug-drug interactions in the elderly

Nimodipine is indicated for a variety of conditions in elderly patients. Elderly patients often have multiple morbidity and receive treatment with a variety of drugs. Therefore, it is important to investigate the possible pharmacokinetic and pharmacodynamic interactions of nimodipine with various drugs commonly prescribed for elderly patients. There were no clinically relevant interactions of nimodipine with any of the following specific agents studied: the antiarrhythmics mexiletine, propafenone, disopyramide or quinidine, digoxin, the beta-adrenoceptor antagonists propranolol or atenolol, nifedipine, warfarin, diazepam, indomethacin, ranitidine or glibenclamide (glyburide). However, there were some notable interactions. In epileptic patients taking the anticonvulsants carbamazepine, phenobarbital (phenobarbitone) and/or phenytoin, there was a 7-fold decrease in the area under the plasma concentration versus time curve (AUC) and an 8- to 10-fold decrease in the maximum plasma concentration of nimodipine. These effects were to be expected, considering the hepatic enzyme-inducing properties of these anticonvulsant drugs. Therefore concomitant use of these agents with oral nimodipine is not recommended. In contrast, epileptic patients treated with nimodipine and valproic acid (sodium valproate) showed an increase in both the AUC (approximately 50%) and maximum plasma concentrations (approximately 30%) of nimodipine, which may be explained by valproic acid inhibiting the presystemic oxidative metabolism of nimodipine. Concomitant administration of cimetidine produced an approximate doubling of the bioavailability of nimodipine. This again was to be expected, considering the known inhibitory effect of cimetidine on cytochrome P450. However, no changes in haemodynamics, clinical or laboratory status or tolerability were observed, and dose adjustment did not appear to be clinically necessary.

Preliminary controlled trial of nimodipine in ultra-rapid cycling affective dysregulation

We report the initial results of the first controlled double-blind trial of nimodipine, a calcium channel antagonist, in the acute and prophylactic treatment of patients with treatment-refractory affective dysregulation. Active drug nimodipine (A) was substituted for placebo (B) in 12 patients. Patients were studied in a B-A-B design, with 3 of the 12 patients rechallenged with active drug in a B-A-B-A design (patients 9, 10, and 11). Five of the nine patients who completed the drug trial responded. One of three patients suffering from ultra-ultra-rapid (ultradian) cycling bipolar II disorder (patient 6) showed an essentially complete response; the other two ultradian patients (patients 4 and 9) showed evidence of a partial response on manic and depressive oscillations, one of which was confirmed in a B-A-B-A design. Only one of five less rapidly, but continuously cycling patients showed an excellent response (patient 10), and this was confirmed in a B-A-B-A design. The one patient who had recurrent brief depression (patient 11) showed a complete resolution of severe depressive recurrences, with response re-confirmed in an extended prophylactic trial with a B-A-B-A design. In the eight patients who completed self-ratings, nimodipine was associated with a significant reduction in the magnitude of mood fluctuations compared with the baseline placebo condition. Further clinical study of nimodipine, a calcium channel blocker with a unique profile of behavioral and anticonvulsant properties, appears warranted in patients with treatment-refractory affective illness characterized by recurrent brief depression and ultradian cycling.

Focal status epilepticus and epilepsia partialis continua in adults and children

Focal status epilepticus and epilepsia partialis continua (FSE-EPC) are most frequently seen with chronic focal progressive encephalitis of Rasmussen and Russian spring-summer encephalitis. FSE-EPC may be the presenting feature of nonketotic hyperglycemic diabetes mellitus but is more often noted as a late complication especially if there is a coexistent cerebral lesion such as cerebral infarction. FSE-EPC may be related to multiple sclerosis, primary or metastatic brain tumors, the MERRF-MELAS syndrome, benign epilepsy of childhood with rolandic spikes, and in some adults with acquired aphasia. The physiological origin of the myoclonic jerks seen in EPC is cortical and may be either spontaneous or provoked by the joint position of the affected limb. The treatment of FSE-EPC is influenced by the underlying disorder.

Dihydropyridine calcium antagonists in mice: blood and brain pharmacokinetics and efficacy against pentylenetetrazol seizures

Dihydropyridine calcium antagonists are candidate anticonvulsants, but little is known of their penetration into brain. Nifedipine (NFD) and nimodipine (NMD) pharmacokinetics were compared in mouse blood and brain, and their activity against pentylenetetrazol (PTZ) was assessed. After intraperitoneal (i.p.) injection, both dihydropyridines achieved peak blood and brain concentrations in 5 min. Estimated blood and brain elimination half-lives (t1/2) of NMD (16.7 and 22.4 min) were slightly longer than those of NFD (11.2 and 14.7 min). Brain and blood concentrations correlated with both NFD (r = 0.701, p less than 0.001) and NMD (r = 0.572, p less than 0.001). Injection of the dihydropyridines as a suspension (Tween 80) did not alter brain penetration, although systemic absorption was more erratic. NFD (p less than 0.001), NMD (p less than 0.02), and carbamazepine (CBZ, p less than 0.001) i.p. inhibited PTZ-induced seizures. Brain concentrations of PTZ were not altered by NFD pretreatment. Combining NFD and CBZ was less effective than giving NFD alone (p less than 0.005). NFD (p less than 0.002) and NMD (p less than 0.001) inhibited PTZ seizures after 2-week oral dosing, but low dosing was more effective than high dosing (p less than 0.002). NFD and NMD cross the blood-brain barrier (BBB) in mice and inhibit PTZ seizures. A possible therapeutic window was identified, and NFD and CBZ were less effective in combination than singly. A pharmacodynamic interaction may exist, inhibiting effective use of dihydropyridines as adjunctive therapy in epileptic patients.

Nifedipine for epilepsy? A double-blind, placebo-controlled trial

The movement of calcium into neurons may be the common denominator for the triggering and propagation of seizure activity. We report results of the first double-blind, placebo-controlled, crossover trial with the dihidropyridine calcium antagonist nifedipine (NFD) as adjuvant therapy in refractory epilepsy. Twenty-two students (12 male, 10 female, age 17-22 years) attending Lingfield Hospital School received NFD retard and matched placebo for 8 weeks in 2 doses (20 and 40 mg b.i.d. each for 4 weeks) with a washout period of 8 weeks between treatment phases. In the 20 students who completed the trial, fewer partial seizures (p less than 0.05) were documented during the first 2 weeks of NFD administration. Similarly, fewer seizure days (p less than 0.05) were reported in the first month of active treatment. This response was not sustained into the second month of the trial. Blind scoring of EEGs suggested a small improvement with NFD (p less than 0.05). More patients reported headache when receiving NFD (p less than 0.02) than placebo, but heart rate and erect and supine blood pressure remained unaffected. Mean maximum NFD concentrations were 13.1 +/- 10.4 ng/ml. A weak correlation was noted between total (p less than 0.05) and partial (p = 0.025) seizure numbers and NFD concentrations following 8 weeks of treatment. This study does not support important anticonvulsant efficacy for NFD as adjuvant therapy for refractory epilepsy at doses appropriate for the treatment of angina or hypertension. Further trials are recommended using higher doses of NFD in less severely affected patients.

Differential effects of valproic acid and enzyme-inducing anticonvulsants on nimodipine pharmacokinetics in epileptic patients

1. The single dose pharmacokinetics of orally administered nimodipine (60 mg) were investigated in normal subjects and in two groups of epileptic patients receiving chronic treatment with hepatic microsomal enzyme-inducing anticonvulsants (carbamazepine, phenobarbitone or phenytoin) and sodium valproate, respectively. 2. Compared with the values found in the control group, mean areas under the plasma nimodipine concentration curve were lowered by about seven-fold (P less than 0.01) in patients taking enzyme-inducing anticonvulsants and increased by about 50% (P less than 0.05) in patients taking sodium valproate. 3. Nimodipine half-lives were shorter in enzyme-induced patients than in controls (3.9 +/- 2.0 h vs 9.1 +/- 3.4 h, means +/- s.d., P less than 0.01), but this difference could be artifactual since in the patients drug concentrations declined rapidly below the limit of assay, thus preventing identification of a possible slower terminal phase. In valproate-treated patients, half-lives (8.2 +/- 1.8 h) were similar to those found in controls.

Nimodipine in refractory epilepsy: a placebo-controlled, add-on study

Twenty-two patients (8 male, 14 female) with refractory epilepsy entered a balanced, double-blind, placebo-controlled crossover trial of nimodipine as adjunctive therapy. Treatment periods of 12 weeks (nimodipine 30 mg tds, 60 mg tds, 90 mg tds each for 4 weeks and matched placebo) were followed by wash-out intervals of 4 weeks. Five patients withdrew (2 side-effects, 1 intercurrent illness, 2 non-compliance). Median values (placebo vs. nimodipine) did not vary for total (17 vs. 18), partial (14 vs. 18) and generalised tonic-clonic seizures (2 vs. 5) or seizure days (13 vs. 13). Monthly analysis also failed to uncover any benefit for nimodipine. Side-effects were reported no more frequently with nimodipine than with placebo and pulse and blood pressure did not alter significantly. Antiepileptic drug levels were not affected by nimodipine treatment but circulating nimodipine concentrations were low. In this trial, nimodipine did not fulfil the promise of its success in animal models of epilepsy. Enzyme induction by concurrent antiepileptic therapy may provide an explanation.

Epilepsy after operative treatment of ruptured cerebral aneurysms

A retrospective analysis of 183 consecutive patients operated on for ruptured cerebral aneurysms and surviving at least one year revealed appearance of postoperative epilepsy in 14 cases (8 per cent) on an average of 10 months (range 0-23 months) after the operation. Factors associated with the development of secondary epilepsy were localization of the aneurysm on the middle cerebral artery, temporary clipping intraoperatively, wrapping technique to treat the aneurysm, and vasospasm seen on the postoperative control angiogram. Intra-operative and/or postoperative ischaemia seems to be the crucial phenomenon favouring the development of epilepsy. Identification of the risk factors may help to focus the anti-epileptic prophylaxis in cases prone to develop seizures.