Current approaches to the use of generic antiepileptic drugs

Generic substitution is encouraged as a cost containment strategy for the management of health care resources. However, in epilepsy, the consequences of loss of symptom control are important, and antiepileptic drugs have narrow therapeutic indices. For this reason, generic substitution may be problematic, and certain health authorities have excluded antiepileptic drugs from overall policy recommendations on generic prescribing. The absence of bioequivalence data among generic forms and the relatively broad criteria for bioequivalence with the branded drug allow differences in drug exposure to arise that may be clinically relevant and necessitate monitoring of plasma levels when switching formulations to avoid loss of seizure control or emergence of side effects. Management of these issues carries a significant cost, which should be weighed carefully against the cost savings acquired when purchasing the drug. Both physicians and patients have a right to be informed and approve before pharmacists make a generic substitution or switch between generics.     

Transcranial magnetic stimulation and epilepsy.

Epileptic conditions are characterized by an altered balance between excitatory and inhibitory influences at the cortical level. Transcranial magnetic stimulation (TMS) provides a noninvasive evaluation of separate excitatory and inhibitory functions of the cerebral cortex. In addition, repetitive TMS (rTMS) can modulate the excitability of cortical networks. We review the different ways that TMS has been used to investigate pathophysiological mechanisms and effects of antiepileptic drugs in patients with epilepsy and epileptic myoclonus. The safety of different TMS techniques is discussed too. Finally, we discuss the therapeutic prospects of rTMS in this field.     

Effects of oxcarbazepine and carbamazepine on the central nervous system: computerised analysis of saccadic and smooth-pursuit eye movements

Oxcarbazepine (OXC) is a new anti-epileptic agent structurally related to carbamazepine (CBZ). OXC seems to have a similar efficacy and a better tolerability profile than CBZ. In the present study we compared the subclinical side-effects on the CNS of OXC and CBZ using a computerised analysis of saccadic and smooth-pursuit eye movements. Six healthy male volunteers (mean age 29 yrs) participated in the study, which was conducted by a double-blind cross-over design. Each subject was given a single dose of either CBZ 400 mg or OXC 600 mg (according to the random assignment) after which the drug effects on eye movements were evaluated. One week later, the trial was repeated using the other drug. The parametrisation of both saccadic and smooth-pursuit eye movements was carried out by measuring a series of performance parameters [e.g. the maximum saccade peak velocity (MSPV) and the typical target velocity (TTV)]. OXC was found to induce a lesser degree of alteration on the values of both MSPV (p = 0.07) and TTV (p less than 0.03) than CBZ. In particular, the TTV values were virtually unaffected by OXC administration, while the effects of CBZ on both variables were particularly evident at 8 and 10 h after dosing which correspond to the time at which the plasma concentrations of CBZ and of its 10,11-epoxide reach the peak. In conclusion, our preliminary results indicate that OXC induces negligible alterations, if any, on the eye movement parameters evaluated in our study.     

Dermoid cyst in undescended testis in a 9-year-old boy.

Testicular dermoid cysts are rare in the pediatric age group: their discovery in an undescended testis is exceptional. The origin of this lesion is still unclear, but it should be considered as a monolayer expression of a mature teratoma. Though surgeons when confronted with these intratesticular cysts have traditionally opted for castration, in presence of small, compact masses, simple enucleation may be recommended, provided that the integrity of the neighboring parenchyma is not affected.     

Effectiveness of simplified dosage schedules on the management of ambulant epileptic patients

The effect of dosage schedules on plasma drug levels was evaluated in two groups of ambulant epileptic patients, whose treatment with diphenylhydantoin (DPH) or phenobarbital (PB) had been simplified by reducing the daily frequency of the dosage regimens. Although the patients received the same milligram per kilogram daily dosages of DPH or PB during the study, the mean plasma levels of the two drugs were significantly higher during the less-frequent dosage regimens. The results obtained suggest that twice-daily dosage schedules of DPH and once-daily dosage schedules of PB are advantageous over more complicated dosage schedules resulting in a higher compliance among ambulant epileptic patients.     

Treatment of epileptic patients with valproic acid does not modify plasma and urine short-chain-fatty acids

The purpose of this study was to evaluate the possible modifications of the plasma and urine short-chain-fatty acid (SCFA) patterns indiced by treatment with valproic acid (VPA). Increased amounts of SCFAs in patients under VPA treatment may explain the presence of VPA-induced hyperammonemia, toxic encephalopathies and rarer Rey-like syndromes recently observed. For this reason we assayed SCFA levels in the plasma and looked for propionic acid in the urine of 10 epileptic patients to whom it was decided to add VPA to their previously unsatisfactory anti-epileptic treatment. This was carried out prior to and during therapy with VPA. 5 of these patients developed toxic encephalopathy with hyperammonemia induced by VPA. Our data show that plasma and urine SCFAs are not modified by VPA treatment. This is so even in patients who have toxic encephalopathy with hyperammonemia indiced by this drug.     

Follow-up of anorectal anomalies: the Italian parents' and patients' perspective

Background

Several studies addressed the long-term follow-up of anorectal anomalies (ARM) in relation to clinical issues (eg, continence) and quality of life.However, most of these studies are based upon questionnaires designed by physicians and/or health-care professionals, which may be sources of bias.

Methods

To investigate whether parents of children (patients themselves or older children or adults) who were born with ARM had the perception that they received appropriate care and follow-up, a survey was carried out in Italy, in 2003, among families with children with ARM. A 20-item questionnaire was mailed to 425 patients and parents listed in the AIMAR (Italian association for anorectal malformation) database and was returned by 209 families.The questionnaire covered different aspects of ARM: type of malformations and surgery, associated anomalies, fecal and urinary continence, as well as aspects about information given to the parents and satisfaction of care and follow-up received.

Result

The patients and parents demonstrated a good understanding of distribution of malformations and their anatomical classification; nevertheless, 67% of responders had to travel outside their living area for surgery. Bowel management (BM) was commonly used among subjects; however, a significant percentage of patients using regular enemas were still soiling (58 patients were clean and 116 soiled).Urinary continence problems were mostly found in females with cloaca; nevertheless, 21 male patients reported occasional dribbling of difficult interpretation. Most subjects were provided with a good explanation about their or their child's malformation at time of reconstructive surgery, but the same level of information was missing about functional prognosis later in life when the need of an appropriate psychologic support was also felt.

Conclusions

Patients and parents born with ARM are generally satisfied with the information received and with the short-term postreconstructive follow-up care.At longer follow-up, although more than a quarter of patients are completely clean, there is a significant percentage of subjects who still soil while following a BM program. This is explained by the small number of nurses and BM specialists who are involved in the rehabilitation process and by the lack of appropriate information about functional prognosis that are conveyed to the parents. In this respect, psychologic support in bridging the gap between cure and care may be critical.     

A functional polymorphism in the SCN1A gene does not influence antiepileptic drug responsiveness in Italian patients with focal epilepsy

A splice site variation (c.603-91G>A or rs3812718) in the SCN1A gene has been claimed to influence efficacy and dose requirements of carbamazepine and phenytoin. We investigated the relationship between c.603-91G>A polymorphism and response to antiepileptic drugs (AEDs) in 482 patients with drug-resistant and 401 patients with drug-responsive focal epilepsy. Most commonly used AEDs were carbamazepine and oxcarbazepine. The distribution of c.603-91G>A genotypes was similar among drug-resistant and drug-responsive subjects, both in the entire population and in the groups treated with carbamazepine or oxcarbazepine. There was no association between the c.603-91G>A genotype and dosages of carbamazepine or oxcarbazepine. These findings rule out a major role of the SCN1A polymorphism as a determinant of AED response.     

Motor imagery in a locked-in patient: evidence from transcranial magnetic stimulation

Motor evoked potentials (MEPs) to transcranial magnetic stimulation were evaluated in a case of locked-in syndrome due to a large pontine infarction. In this patient, magnetic resonance imaging (MRI) and somatosensory evoked potentials demonstrated a tegmental involvement. One month after the attack, no MEP could be recorded from the right abductor digiti minimi (ADM) or either tibialis anterior muscle. On the contrary, MEPs were obtained from the left ADM, although with a prolonged latency and a reduced amplitude. When the patient was requested to think about the abduction of her paralyzed left little finger, the latency and the elicitability of these responses improved as compared with the relaxed condition. These severe MEP alterations correctly predicted a poor recovery of motor function in the chronic stage. However, although the tegmental involvement raises the question of an insufficient cortical motor arousal, preserved motor imagery suggested a normal cortical motor area activation.