Remacemide hydrochloride as an add-on therapy in epilepsy: a randomized, placebo-controlled trial of three dose levels (300, 600 and 1200 mg/day) in a Q.I.D. regimen

Remacemide hydrochloride is a low-affinity, non-competitive N-methyl-D-aspartic acid (NMDA) receptor channel blocker, under investigation in epilepsy. This double-blind, placebo-controlled, multicentre study assessed the safety and efficacy of remacemide hydrochloride or placebo, as adjunctive therapy, in 252 adult patients with refractory epilepsy who were already taking up to three antiepileptic drugs (including an enzyme-inducer). Patients were randomized to one of three doses of remacemide hydrochloride (300, 600 or 1200 mg /day) or placebo Q.I.D., for up to 15 weeks. An increasing percentage of responders (defined as a reduction in seizure frequency from baseline of > or =50%) was seen with increasing remacemide hydrochloride dose. At 1200 mg /day, 23% of patients were responders compared with 7% on placebo. This difference was significant (P = 0.016), as was the overall difference between treatments (P = 0.038). Adverse events: dizziness, abnormal gait, gastrointestinal disturbance, somnolence, diplopia and fatigue were mild or moderate in severity. Carbamazepine and phenytoin plasma concentrations were well controlled and maintained within target ranges, with no evidence of improved seizure control due to increases in the concentrations of these drugs. A dose-dependent, significant, increase in responders following adjunctive remacemide hydrochloride compared with placebo was observed. Remacemide hydrochloride was well tolerated.

Electro-oculography, electroretinography, visual evoked potentials, and multifocal electroretinography in patients with vigabatrin-attributed visual field constriction

PURPOSE

Symptomatic visual field constriction thought to be associated with vigabatrin has been reported. The current study investigated the visual fields and visual electrophysiology of eight patients with known vigabatrin-attributed visual field loss, three of whom were reported previously. Six of the patients were no longer receiving vigabatrin.

METHODS

The central and peripheral fields were examined with the Humphrey Visual Field Analyzer. Full visual electrophysiology, including flash electroretinography (ERG), pattern electroretinography, multifocal ERG using the VERIS system, electro-oculography, and flash and pattern visual evoked potentials, was undertaken.

RESULTS

Seven patients showed marked visual field constriction with some sparing of the temporal visual field. The eighth exhibited concentric constriction. Most electrophysiological responses were usually just within normal limits; two patients had subnormal Arden electro-oculography indices; and one patient showed an abnormally delayed photopic b wave. However, five patients showed delayed 30-Hz flicker b waves, and seven patients showed delayed oscillatory potentials. Multifocal ERG showed abnormalities that sometimes correlated with the visual field appearance and confirmed that the deficit occurs at the retinal level.

CONCLUSION

Marked visual field constriction appears to be associated with vigabatrin therapy. The field defects and some electrophysiological abnormalities persist when vigabatrin therapy is withdrawn.

Regenerable fiber-optic-based immunosensor

An immunosensor is described that is based on fluorescently labeled F(ab') anti-human serum albumin antibody fragments covalently immobilized to the distal end of a fiber-optic probe. When human serum albumin is present, it is bound to the sensor and shields the fluorescent label from the solvent water, and a significant increase in the label fluorescence results. The sensor can be regenerated by simply immersing the sensing tip in chaotropic media. Under these conditions the antigen-antibody complex is selectively disrupted without adversely affecting the sensor. In the present configuration, the same sensor can be recycled over 50 times before the immunosurface inactivates significantly. With proper storage the sensor can last for up to 4 months.

Beta-blockers and sleep: a controlled trial

The effects on sleep of four beta-blockers, atenolol, propranolol, metoprolol and pindolol, were studied in a placebo-controlled trial. Drugs were administered in random order to 10 female volunteers who acted as their own controls. Subjects were tested five times, each test period lasting 10 nights (2 baseline, 2 low dose, 4 high dose, and 2 withdrawal). A questionnaire concerning subjective appreciation of the quality of the previous night's sleep was completed each morning. Night recordings of muscle tension, eye movement, heart rate and electroencephalogram were recorded on paper and magnetic tape. Analysis of the subjective questionnaires showed that recollection of dreaming and awakening in the night was increased by the three lipophilic drugs, propranolol, metoprolol, and pindolol. These results confirm reports in the literature but are contrary to those expected from considering the effects of noradrenaline on sleep. Analysis of physiological records confirmed subjects' reports that waking was increased by the lipophilic drugs. Dreaming (rapid eye movement sleep, REM) was reduced, as predicted from knowledge of the effect of noradrenaline on sleep. Increased awakening leads to an increase in remembered dreaming which explains the otherwise paradoxical results. Although atenolol had no effect on subjective measures of sleep this hydrophilic drug also reduced REM frequency, suggesting that either it has some central effect, or that REM reduction is due to a peripheral 'shielding' effect.

Effect of beta-blockers on psychomotor performance in normal volunteers

The effects of beta-adrenergic receptor antagonists on psychometric tests including vehicle handling, choice reaction time, and kinetic visual acuity (KVA), are reviewed. The beta-blockers had little effect on the performance tests, with the unexplained but reproducible effect of enhanced KVA performance with atenolol. Although the beta-blockers had little effect on performance tests they were shown to have psychotropic effects in normal volunteers. The reasons for the conflicting evidence concerning the effect of these drugs on performance tests is discussed in relation to the present experiments and to variables that may influence response. It is concluded that one should use tests that are as independent as possible from potentially confounding variables. The use of evoked potentials in the electroencephalogram is one such test. A preliminary study is described in which the effects of beta-blockers were detected using visual evoked responses on the electroencephalogram.

The effects of two antidepressants, imipramine and viloxazine, upon driving performance

Forty male volunteers were randomly assigned to one of four treatment groups on a double-blind basis: (1) Imipramine--25 mg t.d.s., (2) Viloxazine--50 mg t.d.s., (3) Placebo, and (4) Control--no tablets. Tests were carried out (1) before treatment, (2) 2 h after the first dose, (3) on Day 3 after 7 doses, and (4) on Day 7 after 21 doses. The driving tasks consisted of (1) weaving around a series of bollards while simultaneously responding to an auditory logic task and (2) a gap acceptance task. Using an analysis of covariance repeated measures design, it was found that imipramine tended to increase the level of risk acceptable to the subject as compared to either placebo or control. Imipramine also impaired performance on other tasks. Viloxazine appeared to be little different from either placebo or control on any of the tasks.

The effects of four antihypertensive agents on the Stroop colour-word test in normal male volunteer subjects

Sixty healthy male volunteers were randomly assigned to one of six treatment groups on a double-blind basis: 1. Atenolol = 50 mg t.d.s. 2. Methyl dopa = 250 mg t.d.s. 3. Propanolol = 40 mg t.d.s. 4. Reserpine = 0.2 mg t.d.s. 5. Placebo. 6. Control = no tablets. Tests were carried out before treatment, 2 h after the first dose, after seven doses, and after 21 doses. Subjects performance on the Stroop Colour-Word Test was assessed in terms of (a) word reading speed and (b) an 'interference' score based on the difference between the incongruous colour word and colour card reading speed. No evidience was found of central effects of the beta-blockers, but personality X drug interactions were found, particularly in the reserpine group.

The effect of thyrotropin releasing hormone on measures of mood in normal women

1 A double blind controlled trial of the psychotropic effects of thyrotropin releasing hormone (TRH) on normal women is described.

2 Single oral doses of this hormone, compared with identical placebo, had no effect on conventional measures of mood, but did cause definite effects as measured by clinical ethological observations of videotaped interviews.

Effects of four commonly-used tranquillizers on low-speed driving performance tests

A double-blind controlled comparison of four commonly-used tranquillizing drugs (haloperidol, amylobarbitone sodium, chlordiazepoxide, and trifluoperazine) against placebo was made in their effects on the performance of volunteers during three low speed vehicle-handling tests. The drugs (with the exception of haloperidol) significantly altered driving behaviour though they did not seem to interact significantly with alcohol. There is, therefore, a strong possibility that such drugs will similarly alter driving performance in patients taking them for therapeutic purposes. Since, as these experiments also show, those affected may be subjectively unaware of it, and routine clinical screening is not sensitive enough to detect them, physicians should warn patients of the probability that their driving performance will be affected by such drugs, particularly during the first few days that they are taken.