Clinical practice. Initial management of epilepsy

Synthesis, resolution and anticonvulsant activity of chiral N-1'-ethyl,N-3'-(1-phenylethyl)-(R,S)-2'H,3H,5'H-spiro-(2-benzofuran-1,4'-imidazolidine)-2',3,5'-trione diastereomers

Four new N-1',N-3'-disubstituted-2'H,3H,5'H-spiro-(2-benzofuran-1,4'-imidazolidine)-2',3,5'-triones bearing a chiral N-3' substituent were synthesized, resolved and their anticonvulsant activity was obtained and determined that the activity was not stereoselective.

[Drug treatment of epilepsy]

Modern medical treatment of epilepsy renders two out of three newly diagnosed epilepsy patients seizure-free. More than 20 drugs are currently available and even for epilepsy specialists it may not be easy to select the drug which is best suited for the individual patient. Current guidelines recommend drugs with proven efficacy and optimal tolerability that address the individual needs of the patient. Non-enzyme-inducing agents are preferred if possible, to protect the patient from loss of efficacy when taking other medications for life-threatening disorders. In one out of three patients, seizure freedom is currently not possible due to drug-resistance, which requires a prompt diagnostic and therapeutic reevaluation of the epilepsy.

Human clinical trails in antiepileptogenesis

Blocking the development of epilepsy (epileptogenesis) is a fundamental research area with the potential to provide large benefits to patients by avoiding the medical and social consequences that occur with epilepsy and lifelong therapy. Human clinical trials attempting to prevent epilepsy (antiepileptogenesis) have been few and universally unsuccessful to date. In this article, we review data about possible pathophysiological mechanisms underlying epileptogenesis, discuss potential interventions, and summarize prior antiepileptogenesis trials. Elements of ideal trials designs for successful antiepileptogenic intervention are suggested.

Anesthetic management of the patient with epilepsy or prior seizures

PURPOSE OF REVIEW

Epilepsy is a clinical disorder of paroxysmal recurring seizures, the diagnosis excluding alcohol or drug withdrawal seizures or such recurring exogenous events as repeated insulin-induced hypoglycemia. Epilepsy has a profound impact on each individual diagnosed with this disease.

RECENT FINDINGS

New antiepileptic drugs (AEDs) have been a major change in the approach to management of patients with epilepsy. These drugs tend to have fewer significant drug interactions and less severe side effects. Nonetheless, first-generation AEDs are still widely used. Propofol and desflurane have reliable anticonvulsant effects, whereas remifentanil in larger doses and sevoflurane appear to support epileptiform activity, although the clinical significance of these observations is unclear.

SUMMARY

The primary concerns for providing anesthesia to the patient with epilepsy are the capacity of anesthetics to modulate or potentiate seizure activity and the interaction of anesthetic drugs with AEDs. Proconvulsant and anticonvulsant properties have been reported for virtually every anesthetic such that these properties become elements of the anesthetic plan in the patient with epilepsy. Moreover, AEDs have many physiologic and pharmacologic effects that can have an impact on an anesthetic.

Ethosuximide, valproic acid, and lamotrigine in childhood absence epilepsy

BACKGROUND

Childhood absence epilepsy, the most common pediatric epilepsy syndrome, is usually treated with ethosuximide, valproic acid, or lamotrigine. The most efficacious and tolerable initial empirical treatment has not been defined.

METHODS

In a double-blind, randomized, controlled clinical trial, we compared the efficacy, tolerability, and neuropsychological effects of ethosuximide, valproic acid, and lamotrigine in children with newly diagnosed childhood absence epilepsy. Drug doses were incrementally increased until the child was free of seizures, the maximal allowable or highest tolerable dose was reached, or a criterion indicating treatment failure was met. The primary outcome was freedom from treatment failure after 16 weeks of therapy; the secondary outcome was attentional dysfunction. Differential drug effects were determined by means of pairwise comparisons.

RESULTS

The 453 children who were randomly assigned to treatment with ethosuximide (156), lamotrigine (149), or valproic acid (148) were similar with respect to their demographic characteristics. After 16 weeks of therapy, the freedom-from-failure rates for ethosuximide and valproic acid were similar (53% and 58%, respectively; odds ratio with valproic acid vs. ethosuximide, 1.26; 95% confidence interval [CI], 0.80 to 1.98; P=0.35) and were higher than the rate for lamotrigine (29%; odds ratio with ethosuximide vs. lamotrigine, 2.66; 95% CI, 1.65 to 4.28; odds ratio with valproic acid vs. lamotrigine, 3.34; 95% CI, 2.06 to 5.42; P<0.001 for both comparisons). There were no significant differences among the three drugs with regard to discontinuation because of adverse events. Attentional dysfunction was more common with valproic acid than with ethosuximide (in 49% of the children vs. 33%; odds ratio, 1.95; 95% CI, 1.12 to 3.41; P=0.03).

CONCLUSIONS

Ethosuximide and valproic acid are more effective than lamotrigine in the treatment of childhood absence epilepsy. Ethosuximide is associated with fewer adverse attentional effects. (ClinicalTrials.gov number, NCT00088452.)

A seizure attributed to ofloxacine in a woman undergoing detoxification for alcohol dependence

Objective. To report one case of seizure following administration of ofloxacin. Case Summary. A 38-year-old woman with alcohol dependence but no prior history of seizure disorder admitted in our inpatient alcohol detoxification program was prescribed ofloxacin four days after admission for a lower urinary tract infection. She was currently prescribed diazepam 30 mg per day. This treatment was continued without modification following admission. Forty eight hours after starting ofloxacin and after receiving five doses of oral ofloxacin, the patient experienced a seizure. Ofloxacin treatment was stopped and no further seizures occurred. Neurological examination of the patient, laboratory tests, computerized tomography with contrast enhancement and electroencephalography did not detect any abnormalities. Up to the last consultation, six months after admission, the patient has reported no recurrence of the seizure. Discussion. Quinolone antibiotics vary in their ability to induce seizures, with ofloxacin having one of the least potentials. In the present case, the seizure could be attributed in all probability to taking ofloxacin; since she had no previous history of seizures, she did not present an alcohol withdrawal syndrome, benzodiazepine treatment was not modified, the seizure occurred 48 h after taking ofloxacin, but seven days after stopping drinking, no alternative aetiologies for the seizure could be identified and no seizure recurrence was reported over the following seven months. Of reported cases of seizures in patients treated with fluoroquinolones, none concerned patients with alcohol dependence or patients treated with benzodiazepines. Conclusions. The present case alerts us to the possibility that seizures may occur in alcohol dependent patients treated with benzodiazepines who concomitantly prescribed a fluoroquinolone. These widely-used antibiotics should thus be prescribed with caution to patients undergoing detoxification for alcohol dependence, particularly if they are also taking benzodiazepines, irrespective of whether they have a previous history of seizures or not.

The Effect of Carbapenem Antibiotics on Plasma Concentrations of Valproic Acid

Objective:

To critically evaluate the mechanisms of the interaction between valproic acid and carbapenem antibiotics.

Data Sources:

A PubMed search (January 1971–June 2009) was performed to identify literature on the interaction between valproic acid and carbapenem antibiotics. Additional references were identified through review of bibliographies of identified articles.

Study Selection and Data Extraction:

Data on the mechanisms of the interaction between valproic acid and carbapenem antibiotics were extracted from identified references that were published in English.

Data Synthesis:

Valproic acid plasma concentrations fall markedly during concomitant administration with carbapenem antibiotics due to a combination of absorption, distribution, and metabolism mechanisms. Carbapenems appear to inhibit the intestinal transporter of valproic acid, thereby reducing absorption of orally administered valproic acid. In vivo experiments in rats demonstrate a 57% reduction in absorption of orally administered valproic acid in the presence of imipenem. Followup studies in Caco-2 cells suggest that the inhibition probably occurs at the basolateral membrane. In addition, enterohepatic recycling of valproic acid may be diminished due to carbapenem activity against gut flora producing β-glucuronidase. When rabbits and rats were given intravenous valproic acid-glucuronide, the glucuronide metabolite of valproic acid, 50–90% of the conversion back into valproic acid was inhibited in the presence of a carbapenem. An increase in erythrocyte distribution of valproic acid has also been observed in the presence of carbapenems. After intravenous administration of a carbapenem and valproic acid, valproic acid plasma concentrations fell in the presence of a carbapenem, yet whole blood concentrations of valproic acid did not change significantly. Follow-up studies suggest that the mechanism of this distribution shift is that multidrug resistance proteins on adenosine triphosphate–binding cassette transporters on erythrocyte membranes are inhibited by carbapenems. Thus, valproic acid is not effluxed out of the erythrocytes. Finally, carbapenems may enhance glucuronidation of valproic acid by increasing UDP-glucuronic acid levels. In rats, UDP-glucuronic acid levels increased by 1,7-fold in the presence of panipenem, which was proportionate to the increase in valproic acid-glucuronide formation.

Conclusions:

Published data demonstrate a serious and complex interaction between valproic acid and carbapenem antibiotics. Coadministration should be avoided, but if no other antibiotic therapies exist, it is imperative to monitor valproic acid concentrations more frequently. Clinicians should anticipate higher doses of valproic acid to maintain therapeutic serum concentrations during coadministration and subsequent dose reductions upon discontinuation of the carbapenem antibiotic.

[New international classification of epilepsy and new antiepileptic drugs for medically intractable epilepsy]

The task force of the international league against epilepsy (ILAE) proposed the "Diagnostic scheme for people with epileptic seizures and epilepsy" in 2001. The 2001 diagnostic scheme was updated in 2006. The ILAE Core Group recommended the new classification to replace the previous one (ILAE, 1981, 1989). However, the new classification is too complex to use for clinicians except expert epileptologists. About 10 new antiepileptic drugs are launched recently. Among them, gabapentine, topiramate, and lamotrigine have been approved in Japan as adjunctive therapy for medically intractable seizures. The advantage of the new antiepileptic drugs includes newer mechanism of action, broad spectrum of anti-seizure effects, fewer side effects, and lesser drug interactions. The rational polytherapy is necessary for refractory epilepsy. The majority of elderly patients with new onset epilepsy become seizure free on antiepileptic monotherapy, often with modest dose. We are now in the new era of epilepsy treatment.

Association between antiepileptic drug switching and epilepsy-related events

Switching between bioequivalent antiepileptic drugs (AEDs) in patients with epilepsy remains a concern because of possible untoward effects owing to a narrow therapeutic range. We investigated the association between switching A-rated AEDs and epilepsy-related events. We conducted a case-control study using claims from the MarketScan database. Cases were defined by an emergently treated epilepsy-related event with the primary diagnosis of epilepsy. Controls had an epilepsy outpatient office visit. Eighty-four of 757 (11.1%) cases and 147 of 2271 (6.5%) controls experienced an A-rated switch. The odds of an epilepsy-related event were 1.78-fold higher for switchers (95% CI 1.35 to 2.36) and, when adjusted for gender and total number of AED prescriptions filled, 1.57-fold higher (95% CI=1.17-2.10). Switching between A-rated formulations of AEDs is associated with an increased risk of emergently treated epilepsy-related events. These findings suggest that care should be taken when considering a switch between A-rated AEDs in patients with epilepsy.