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Biomedical subjects

A Richens

Publications and source records attributed to A Richens.

At least 91 records · Page 5Linked to original sources
PubMed1987

Video EEG telemetry using an ambulatory EEG cassette recorder.

A system of video/EEG monitoring is described which is complementary to out-patient ambulatory EEG recording and prolonged hospital admission for intensive assessment. An ambulatory EEG cassette recorder is incorporated in the system which increases the usefulness of this equipment. In addition all the recorded EEG may be rapidly reviewed. This system has proved valuable in the management of selected patients seen in a special clinic for epilepsy.

Electroencephalography↗
PubMed1987

Lamotrigine: single-dose pharmacokinetics and initial 1 week experience in refractory epilepsy.

Twenty-three residential patients on chronic antiepileptic drugs (AEDs) were entered into an open study of 4 weeks duration. Baseline variables and seizure frequency were determined in the first week. All patients received a single dose of lamotrigine in the second week to determine single-dose pharmacokinetic parameters. Twenty patients then received daily or twice daily lamotrigine for a week. Post-treatment seizure frequency was observed for a further week. Patients taking liver enzyme inducing antiepileptic drugs showed a mean lamotrigine plasma elimination half-life (T1/2) of 14 h (+/- 7) (T1/2 of normal volunteers = 24 h) and those taking sodium valproate and an inducing AED showed a mean lamotrigine T1/2 of 30 h (+/- 10). The plasma concentrations of co-administered sodium valproate, phenytoin, carbamazepine, phenobarbitone and primidone were not altered by 1 week lamotrigine dosing. There was a significant reduction in complex partial seizures in the treatment week compared with baseline. Some patients showed a marked increase in seizure frequency on stopping lamotrigine. There was an increase in reports of drowsiness during lamotrigine administration, but there were no clinically significant changes in any safety measure.

Adolescent↗
PubMed1987

An enhanced serum prolactin response to TRH in the presence of GABA transaminase inhibition.

Patients with epilepsy were found to have an increased 20 minute prolactin response to intravenous TRH stimulation when receiving the GABA-T inhibiting drug vigabatrin. Enhanced GABA activity may either reduce basal prolactin levels whilst allowing a normal pituitary response to TRH stimulation, or may overcome the inhibitory effects of dopamine on pituitary prolactin release.

4-Aminobutyrate Transaminase↗
PubMed1987

Oral phenytoin pharmacokinetics during omeprazole therapy.

1. In a double-blind crossover study 10 healthy males received either placebo or omeprazole (40 mg day-1) for 9 days, a single dose of phenytoin (300 mg) being taken on the seventh day. 2. Omeprazole significantly increased the area under the curve (0 to 72 h) of phenytoin (mean +/- s.e. mean) from 121.6 +/- 14.0 to 151.4 +/- 13.6 micrograms ml-1 h) (P less than 0.01). 3. The peak concentration, and apparent elimination half-life of phenytoin also tended to be increased though not significantly. 4. The omeprazole-phenytoin interaction observed may be clinically important because of the low therapeutic index associated with phenytoin.

Administration, Oral↗
PubMed1987

Folate metabolism and problem behaviour in mentally handicapped epileptics.

Two groups of mentally handicapped residents were studied consisting of 32 epileptics on anti-epileptic medication and 32 non-epileptic controls. The epileptic group showed a significantly low serum folate level compared with the non-epileptic control group. Serum vitamin B12 and behaviour rating did not show any significant difference between two groups. Comparison of patients receiving phenytoin and those who were not showed significantly lower serum folate in the sub-group receiving phenytoin, but there was no significant difference between the sub-groups with respect to vitamin B12 or behaviour problem rating.

Adolescent↗
PubMed1987

Metabolism and urinary excretion of 5-amino salicylic acid in healthy volunteers when given intravenously or released for absorption at different sites in the gastrointestinal tract.

In six healthy subjects serum concentrations of 5 amino salicylic acid (5ASA) and acetyl 5ASA were measured for up to 24 hours, and urinary excretion over 48 hours. After an intravenous injection of 3.26 mmol 5ASA serum concentrations fell rapidly with a distribution half-life of 17 +/- 2 min and an elimination half-life of 42 +/- 5 min. After 45 minutes acetyl 5ASA became the dominant compound and after seven hours serum concentrations of both components were almost unrecordable. Orally ingested 5ASA in three preparations to ensure its release in the stomach, small intestine and ileocaecal region respectively gave lower serum concentrations and urinary excretion than those obtained after an intravenous infusion. Bioavailabilities which ranged from 19% for ileocaecal release to 75% for release in the upper gastrointestinal tract, were calculated from areas under the serum concentration curves. Urinary excretion of 5ASA and its acetyl metabolite over 48 hours was 78%, 52%, 55%, and 21% respectively of the dose given intravenously and orally for gastric, small intestinal and ileocaecal release.

Adult↗
PubMed1987

The framework of medical care for epilepsy.

In this article, the range of medical and other specialized services for epilepsy are reviewed. The objectives are outlined and the present shortcomings are highlighted. Suggestions are made for improvements and in particular we draw attention to the need and place for the development of epilepsy clinics for patients whose epilepsy poses continuing problems. Services for epilepsy have been reviewed in various government sponsored reports over a number of years. The latest is a wide ranging review with specific recommendations for improvements. In this paper, we describe the overall framework of case required to deal with epilepsy, emphasizing particularly the problems of chronic uncontrolled epilepsy and incorporating suggestions made in the recent report.

Epilepsy↗
PubMed1986

Human cognitive function following binedaline (50 mg and 100 mg) and imipramine (75 mg): results with a new battery on tests.

The effects of two single oral doses of binedaline (50 and 100 mg), imipramine (75 mg) and placebo were compared on a range of psychological tasks (logical reasoning, the Stroop test, and five-choice serial reaction) in healthy young volunteers. The tasks, together with a mood adjective check-list, were completed prior to drug administration and 1, 2, 4 and 8 h post-dose. Binedaline had no significant effect on any of the task parameters. Imipramine impaired performance on all but the Stroop test at 2 h after drug administration. At 1, 2 and 4 h, ratings on the "deactivation" dimension of the mood adjective check-list were significantly higher following imipramine when compared to placebo. The results are discussed in terms of some general considerations about the selection and scoring of tasks to be used in the screening of drugs.

Adult↗
PubMed1986

Pharmacokinetics of antipyrine in epileptic patients.

The pharmacokinetics of antipyrine were examined after oral and intravenous administration to 20 epileptic subjects receiving antiepileptic drug therapy. Bioavailability was essentially complete (mean bioavailability 101.2% +/- 14.4 (s.d.] indicating that even in enzyme induced subjects, antipyrine behaves as a restrictively eliminated compound with negligible presystemic elimination in the gut or liver. Of the generally used measures of enzyme induction (oral clearance, oral half-life and intravenous half-life) oral clearance was the most closely related to the intravenous clearance of antipyrine (r = 0.919, P less than 0.001). Oral antipyrine administration is an alternative to intravenous administration in epileptic subjects who are enzyme-induced.

Administration, Oral↗
PubMed1986

Zopiclone produces effects on human performance similar to flurazepam, lormetazepam and triazolam.

The cognitive function and psychomotor performance of 10 healthy male volunteers were measured following single oral doses of: zopiclone (7.5 mg), flurazepam (15 mg), lormetazepam (1 mg), triazolam (0.25 mg) and placebo. The performance tests selected (stroop task, five choice serial reaction time, memory span, logical reasoning, mood and saccadic eye movement analysis) were thought to reflect aspects of normal daily activity. The tests demonstrated a clear reduction of performance for all active treatments. No drug emerged as the most potent sedative overall, as each of the tests was affected to a different degree by each drug. Drug effects were not qualitatively different between active treatments so that zopiclone was indistinguishable from the three benzodiazepines with which it was compared.

Adult↗
PubMed1986

The effect of lamotrigine, a novel anticonvulsant, on interictal spikes in patients with epilepsy.

Lamotrigine, a novel anticonvulsant, has been evaluated in patients with epilepsy using the method of interictal EEG spike counting. In a randomised double-blind trial it was found that oral lamotrigine (240 mg) was more effective than placebo, but less effective than diazepam (20 mg) in suppressing interictal spikes. Further clinical evaluation of lamotrigine is recommended in patients with epilepsy.

Adult↗
PubMed1986

The effects of repeated doses of temazepam and nitrazepam on several measures of human performance.

The effects of six nightly doses of temazepam (20 mg), nitrazepam (10 mg) and placebo on saccadic eye movements, critical flicker fusion threshold, choice reaction time and mood were studied in eight volunteers. Performance was measured on nights 1 and 6 of each treatment. Nitrazepam produced a residual performance impairment on night 1 that disappeared by night 6, despite higher serum concentrations of the drug on the sixth night of treatment. Temazepam, with a shorter elimination half-life, produced no significant performance impairment on night 1, but by night 6 a significant impairment of saccadic eye movements (p less than 0.05) was seen 1 hour after drug intake. We conclude that tolerance to the sedative action of nitrazepam developed over the 6-night period of the study. No evidence of tolerance was seen with temazepam. No residual effects of temazepam (20 mg) were seen the morning after the night-time drug administration.

Anti-Anxiety Agents↗
PubMed1986

A pharmacodynamic evaluation of midazolam as an antiepileptic compound.

Midazolam is a water soluble 1,4 benzodiazepine which is suitable for intramuscular administration. It is currently used for pre-medication and the induction of anaesthesia. Its antiepileptic properties have been evaluated by studying its effect on interictal spikes on the EEG of six adult epileptic patients. The results indicate that intramuscular midazolam 15 mg is more effective than intramuscular diazepam 10 mg in abolishing interictal spikes and as effective as intravenous diazepam 20 mg five minutes after administration.

Adult↗
PubMed1986

Exercise-induced hand tremor: a possible test for beta 2-adrenoceptor selectivity in man?

The effects of intravenous doses of propranolol, sotalol, timolol, atenolol and placebo on exercise-induced tachycardia and exercise-induced increases in hand tremor were assessed in four healthy volunteers. All active drugs produced significant reductions in exercise-induced tachycardia. Exercise caused consistent significant increases in hand tremor which were blocked by the three non-cardioselective drugs but not by atenolol or placebo. The blockade of exercise-induced hand tremor is suggested as a possible test for the assessment of the selectivity of beta-adrenoceptor blockade in man.

Adrenergic beta-Antagonists↗
PubMed1985

Tremor: an alternative approach for investigating adrenergic mechanisms in thyrotoxicosis?

The effects of nadolol (or placebo) and carbimazole on thyrotoxic tremor were investigated in 18 thyrotoxic patients. Both nadolol and carbimazole produced significant reductions in tremor power although nadolol did not cause any change in serum free tri-iodothyronine and free thyroxine concentrations. The results are discussed in terms of the pathogenesis of thyrotoxic tremor and the potential usefulness of tremor in the investigation of adrenergic mechanisms in thyrotoxicosis.

Adrenergic beta-Antagonists↗