Carbamazepine hypersensitivity and the use of lymphocyte proliferation responses

This report describes a case of multisystem failure in a 5-year-old boy who was being treated with carbamazepine for a seizure disorder. Carbamazepine hypersensitivity was diagnosed from the combination of the clinical constellation and the results of the patient's peripheral blood monocyte proliferation responses to both carbamazepine and a panel of other medications.     

Manic-like state after bilateral orbitofrontal and right temporoparietal injury: efficacy of clonidine

A manic-like state occurred in a 44-year-old right-handed woman with bilateral orbitofrontal and right temporoparietal traumatic contusions. In a brief trial, we assessed the effect of clonidine, carbamazepine, dopa therapy, and placebo on manic symptoms and cognitive functions. Clonidine rapidly reversed the manic syndrome. The patient's behavior did not change with carbamazepine and worsened with levodopa. We suggest that the manic-like syndrome was related to noradrenergic overactivity secondary to the fronto-orbital lesions.     

Clinically Significant Carbamazepine Drug Interactions: An Overview

Summary: Knowledge of the principles of drug action and distribution contributes to an understanding of the occurrence of drug interactions. The pharmacologic action of most drugs is postulated to occur by the formation of a drug-receptor complex at the site of action that is capable of altering the physiologic response of the target system. The therapeutic response observed depends on the sum of the numerous factors that can affect the disposition pattern of a drug. In an individual, the response to a given drug dose remains relatively constant, but in a large population, a fixed dose can produce a range of plasma concentrations and therefore varied clinical responses. For most drugs, there is a linear relationship between the total dose and the plasma concentration achieved at steady state. Saturation, or zero-order, kinetics accounts for nonlinear increases in drug concentration with dosage increase. Drug-drug interactions with carbamazepine include several types. (1) Autoinduction of carbamazepine metabolism increases the carbamazepine clearance rate, decreases the half-life, and decreases serum concentrations; the clinician must reevaluate a patient's serum levels at 4 to 6 weeks after initiation of therapy. (2) Carbamazepine induces the metabolism of other antiepileptic drugs, enhancing the clearance of phenytoin, primidone, valproic acid, clonazepam, and ethosuximide. (3) Other drugs added to the epileptic patient's drug regimen may induce the metabolism of carbamazepine, causing increased serum concentrations. (4) Inhibition of carbamazepine metabolism by other drugs can also occur; symptoms of drug intoxication rapidly follow. Interactions occur between carbamazepine and macrolide antibiotics, cimetidine, propoxyphene, and isoniazid. Drug-drug interactions are preventable. It is the responsibility of every physician to be alert to the potential for their occurrence whenever a change in the epileptic patient's drug regimen is made.     

Reversal by phenytoin of carbamazepine-induced water intoxication: a pharmacokinetic interaction.

The hypothesis that phenytoin may antagonise the antidiuretic effect of carbamazepine has been examined by comparing the free water clearance response to a standard water load in 36 patients stabilised on different drug regimes. The diuretic response to the water load was significantly greater in patients receiving chronic treatment with carbamazepine and phenytoin in combination than in matched control subjects receiving carbamazepine as a single drug. Acute administration of phenytoin (1,100 mg), however, had no significant influence on carbamazepine-induced antidiuresis. Evidence is presented that reversal of the antidiuretic effect of carbamazepine by chronic phenytoin administration is secondary to a marked reduction of the serum carbamazepine concentration during combined therapy. These results suggest that the risk of developing water intoxication is greater in patients receiving carbamazepine alone than in those receiving phenytoin in combination. Since the antidiuretic effect is correlated with the serum carbamazepine concentration rather than with the prescribed daily dose, monitoring the serum level of the drug is likely to provide the best rational approach to the prevention of excessive water retention.     

Plasma arginine vasopressin concentrations in epileptics under monotherapy

Plasma arginine vasopressin concentrations were determined by radio-immunoassay in 112 adult epileptics who were taking carbamazepine, phenytoin, primidone, or sodium valproate in long-term monotherapy, and in 19 controls. No significant difference was found between the groups, but some epileptics taking carbamazepine and primidone showed low values. Serum concentrations of carbamazepine did not correlate with the concentrations of plasma arginine vasopressin. In conclusion, there was no evidence of a stimulating effect of chronic carbamazepine medication or a special inhibiting effect of phenytoin on the release of vasopressin arginine from the posterior pituitary.     

Water intoxication in epileptic patients receiving carbamazepine.

Plasma sodium and osmolality were determined in 80 adult epileptic patients receiving chronic treatment with carbamazepine and in 50 control patients treated with other anticonvulsant drugs. Mean plasma osmolality was significantly lower in the carbamazepine-treated patients but mean plasma sodium did not differ in the two groups. Hyponatraemia was found in five of the carbamazine-treated patients and hypo-osmolality in six. None of the control patients had hyponatraemia and only one had a borderline low osmolality. Three of the 13 patients receiving carbamazepine alone were hyponatraemic. Plasma sodium concentration correlated negatively with both daily carbamazepine dose and serum carbamazepine level. Free water clearance after an oral water load was determined in six patients on carbamazepine alone and in six normal subjects not receiving drug therapy. The capacity of some of the patients to excrete the water load was found to be grossly impaired.     

Efficacy and tolerability of conversion to monotherapy with lamotrigine compared with valproate and carbamazepine in patients with epilepsy

OBJECTIVE: This randomized, open-label study was designed to compare the efficacy and tolerability of lamotrigine monotherapy with those of valproate and carbamazepine monotherapy in patients with epilepsy whose seizures were uncontrolled on their prestudy antiepileptic drug monotherapy. METHODS: Patients meeting eligibility criteria were randomized 2:1 to lamotrigine:carbamazepine or lamotrigine:valproate. The treatment phase was divided into a 4-week dose-escalation phase (Weeks 1-4), during which lamotrigine, carbamazepine, or valproate was added to patient's prestudy monotherapy; an 8-week add-on phase (Weeks 5-12), during which patients were stabilized on both the study medication and their prestudy antiepileptic therapy; an 8-week withdrawal phase (Weeks 13-20), during which prestudy antiepileptic therapy could be withdrawn if clinically appropriate; and an 8-week monotherapy phase (Weeks 21-28), during which patients could be treated with study medication as monotherapy. RESULTS: The numbers of patients randomized to the carbamazepine and valproate arms of the study were 144 (98 lamotrigine, 46 carbamazepine) and 158 (105 lamotrigine, 53 valproate), respectively. Successful monotherapy sustained for at least 7 weeks was achieved in comparable percentages of patients in the lamotrigine group (56%) and the carbamazepine group (54%) and in more patients in the lamotrigine group (49%) than the valproate group (40%). Among monotherapy completers, the percentage of patients with zero seizures during the monotherapy phase was comparable for lamotrigine (41%) and carbamazepine (30%) and significantly higher (P<0.05) with lamotrigine (32%) than with valproate (11%). No differences between treatments were observed with respect to time to treatment failure or time to first seizure. Lamotrigine was also better tolerated than carbamazepine or valproate. CONCLUSION: Lamotrigine monotherapy was as effective as and better tolerated than carbamazepine or valproate monotherapy in patients whose seizures were uncontrolled on their prestudy antiepileptic drug monotherapy.     

Fatal agranulocytosis in a chronic schizophrenic patient treated with carbamazepine

A chronic schizophrenic patient developed a fatal agranulocytosis 1 month after beginning to take carbamazepine for aggression. Routine hematological monitoring was not carried out. This case highlights the need for psychiatrists' increased awareness of the possible hematological complications of carbamazepine.     

Hyponatremia during carbamazepine therapy in patients with intellectual disability

Carbamazepine is an anticonvulsant and psychotropic medication commonly used in the treatment of people with intellectual disability (ID). The incidence of hyponatremia during treatment in this population is unclear. The present study aimed to determine the prevalence of hyponatremia during carbamazepine treatment in patients with ID, and to investigate the risk factors and clinical features of this condition. The prevalence of hyponatremia was retrospectively assessed in 53 people receiving carbamazepine (subject group) and 64 people not receiving carbamazepine (control group) who lived in a residential centre for people with ID. The relationship between serum sodium level, sex, age, daily carbamazepine dose and serum carbamazepine levels was examined. The prevalence of the clinical features of hyponatremia was assessed in this population using a checklist. The prevalence of hyponatremia was 41.5% and 9.4% in the subject and control groups, respectively. The mean serum sodium level in the subject group was significantly lower than that in the control group. Hyponatremia correlates significantly with a high daily carbamazepine dose and a high serum carbamazepine level. The checklist of clinical features was not useful in detecting hyponatremia clinically. Hyponatremia is a common occurrence in this population. In the light of the uncertain significance of mild, chronic hyponatremia, the value of routine monitoring of serum electrolytes has yet to be established.     

Evolution of serum lipids and lipoprotein (a) levels in epileptic children treated with carbamazepine, valproic acid, and phenobarbital

The concentration levels of serum lipids and lipoprotein (a) were measured in 20 children receiving carbamazepine, 25 children receiving valproic acid, and 5 children receiving phenobarbital at the following times: (1) during chronic treatment while eating a normal diet, (2) during chronic treatment while eating a low-fat diet (children treated with carbamazepine and phenobarbital with high levels of total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol), and (3) 3 months after the end of treatment with antiepileptic drugs. Patients during chronic treatment and eating a normal diet revealed significant changes in lipids, but when we reevaluated the groups of children treated with carbamazepine and phenobarbital when they were eating a low-fat diet and reevaluated the three groups of children 3 months after the end of treatment, a complete return to normal of all parameters was observed. These data demonstrate that the changes induced by these drugs are transient, reversible, and influenced by a low-fat diet. (J Child Neurol 2006;21:48-53).     

Exacerbation of psychosis after discontinuation of carbamazepine treatment

Carbamazepine alone or carbamazepine plus neuroleptic was administered to 20 chronic schizophrenic patients. Upon abrupt discontinuation two of the 20 patients had exacerbations of their psychoses characterized by paranoia, hostility, and agitation. The authors discuss the possibility of a carbamazepine withdrawal syndrome.     

GABA receptor alterations after chronic lithium administration. Comparison with carbamazepine and sodium valproate.

1. Effects of lithium, carbamazepine, sodium valproate and baclofen on GABA receptors were examined in several regions of the rat brain. 2. [3H]Muscimol (MUS) and [3H] (-)baclofen (BAC) were used to label GABAA and GABAB receptors, respectively, in synaptic membranes from rat brain. 3. Single treatment with lithium chloride, carbamazepine or sodium valproate did not change [3H]MUS or [3H]BAC binding in the frontal cortex, hippocampus and thalamus. 4. Following chronic treatment with lithium, carbamazepine or sodium valproate, [3H]BAC binding was significantly increased in the hippocampus but not in the frontal cortex, thalamus or striatum. 5. [3H]Muscimol binding did not change in any region examined after chronic treatment with lithium, carbamazepine or sodium valproate. 6. Single and chronic administration of baclofen did not change [3H]MUS or [3H]BAC binding. 7. One common mechanism of action of mood stabilizers may be mediated by GABAB receptors in the hippocampus.     

Treatment of alcohol withdrawal symptoms in hospitalized patients. A randomized, double-blind comparison of carbamazepine (Tegretol) and barbital (Diemal)

Seventy-two hospitalized patients with alcohol withdrawal symptoms were treated with either carbamazepine (Tegretol) or barbital ( Diemal ) in a randomized, double-blind trial. The dose of trial medication as well as the duration of treatment was individual, corresponding to the conventional treatment schedule. During the trial period daily records were kept of target withdrawal symptoms, global evaluation, the patient's subjective feeling and unwanted effects. Sixty patients completed the treatment successfully. The two treatment groups were homogeneous as regards patient characteristics, pre-treatment disease severity and drop-out rate. No statistically significant differences were found in efficacy between the two treatments, and both drugs were well tolerated. It is concluded that carbamazepine is a valuable alternative drug in the treatment of mild and moderate alcohol withdrawal symptoms.     

Diurnal fluctuations in free and total steady-state plasma levels of carbamazepine and correlation with intermittent side effects

The relationship between diurnal fluctuations in free (unbound) and total plasma carbamazepine levels and the appearance of intermittent side effects was investigated in nine epileptic patients receiving chronic therapy with carbamazepine, alone or in combination with phenobarbital. On a three-times-daily or four-times-daily dosing schedule, both total and free carbamazepine levels fluctuated considerably (on an average, 41 and 45%, respectively, around the mean). Side effects (particularly diplopia and nystagmus) were observed in five patients and showed an intermittent pattern in four. Side effects were never found at total carbamazepine levels less than 34 mumol/L but invariably appeared at levels greater than 38 mumol/L. At levels between 34 and 38 mumol/L adverse effects were inconsistently observed. The correlation between plasma carbamazepine levels and manifestations of toxicity was slightly stronger when free rather than total levels were considered. Side effects were always apparent at free levels greater than 7.2 mumol/L. These data underline the limitations of relying on a single drug level determination during the monitoring of carbamazepine therapy and emphasize the necessity of carefully adjusting the dosing schedule, to minimize the appearance of intermittent adverse effects.     

Differential effect of cimetidine on serum concentrations of carbamazepine and phenytoin

Cimetidine is an inhibitor of drug metabolism. We studied the effects of cimetidine (1,200 mg/d) on steady-state serum concentrations of carbamazepine and phenytoin in 11 epileptic volunteers. The mean serum carbamazepine concentration was unchanged after 7 days of cimetidine treatment. Five subjects were taking phenytoin concurrently; their mean serum phenytoin concentration was significantly increased after 7 and 10 days of cimetidine treatment and returned to baseline 2 weeks after cimetidine was discontinued. Cimetidine apparently inhibits the clearance of phenytoin but not of carbamazepine in adults on chronic therapy.     

Anticonvulsant activity of carbamazepine and diphenylhydantoin against maximal electroshock in mice chronically treated with aminophylline

Summary The anticonvulsant activities of both carbamazepine and diphenylhydantoin alone (after a single intraperitoneal administration) or combined with aminophylline were studied against maximal electroshock-induced convulsions in male mice. Aminophylline (injected acutely at 50 mg/kg) significantly increased the ED₅₀ values of both antiepileptics. Given for three days, aminophylline (50 mg/kg, twice daily) still impaired the potency of both antiepileptics and after chronic aminophylline administration a further decrease in the protective activity of carbamazepine and diphenylhydantoin was found. Specifically, after 14 days of aminophylline treatment, ED₅₀s for carbamazepine and diphenylhydantoin were 26 and 19 mg/kg, respectively. These ED₅₀s were significantly elevated compared to values determined after acute aminophylline treatment (21.2 and 14.9 mg/kg, respectively). Plasma levels of both antiepileptics were unaffected by chronic aminophylline which seems to exclude a pharmacokinetic interaction in terms of total plasma levels at least.The present results clearly indicate that the aminophylline-induced impairment of the anticonvulsant activity of carbamazepine and diphenylhydantoin is enhanced over time. This may render aminophylline a hazardous drug to epileptic patients who are prescribed this smooth muscle relaxant.     

A case of epileptic negative myoclonus: therapeutic considerations.

This study presents a patient with epileptic negative myoclonus who showed interictal focal epileptic discharges in the centrotemporal region. The patient's seizures were exacerbated by carbamazepine, zonisamide, and valproate, but completely controlled by ethosuximide, and were suggested to have some relation with thalamocortical oscillation mechanisms. Ethosuximide is supposed to be a drug of worth to try to use in epileptic negative myoclonus patients with centrotemporal spike foci.     

Carbamazepine as adjunctive treatment in nonepileptic chronic inpatients with EEG temporal lobe abnormalities

A 15-week double-blind, randomized, within-patient design was used to assess carbamazepine versus placebo as adjunctive treatment in chronic hospitalized psychiatric inpatients (predominantly schizophrenic) with EEG temporal lobe abnormalities but no clinical evidence of epilepsy. A statistically significant improvement on carbamazepine was found on all clinical rating measures used (Overall Clinical Rating, Brief Psychiatric Rating Scale, and Global Assessment). The results also appeared to be clinically significant.     

Prophylactic effects of phenytoin, phenobarbital, and carbamazepine examined in kindling cat preparations.

Prophylactic effects of phenobarbital, phenytoin (diphenylhydantoin), and carbamazepine were examined in amygdaloid kindling preparations in cats. Daily electrical stimulation was delivered at the time of peak plasma levels. Comparative examination of the chronological pattern of the clinical seizure development, after discharge growth, and formation of distant independent spike foci was made between periods of kindling with chronic drug administration and of rekindling without drugs. Both phenobarbital and carbamazepine were effective, but phenytoin was totally ineffective. Prophylactic action of phenobarbital and carbamazepine was mainly through the suppression of the development of motor seizures manifestations in the former and the same with the development of sustained after discharge in the latter. The kindling preparation appears to possess many desirable features as an ideal model of human epilepsy for the purpose of assessment and recruitment of potential antiepileptic drugs and development of a rational pharmacotherapeutic approach for the management and prevention of seizure disorder.