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Biomedical subjects

A Richens

Publications and source records attributed to A Richens.

At least 127 records · Page 7Linked to original sources
PubMed1984

Pituitary responsiveness to gonadotrophin-releasing and thyrotrophin-releasing hormones in epileptic patients receiving carbamazepine or phenytoin.

Pituitary responsiveness to gonadotrophin-releasing (LHRH) and thyrotrophin-releasing (TRH) hormones was studied in 19 epileptic patients receiving long-term carbamazepine or phenytoin therapy and 14 normal control subjects. Baseline prolactin levels were normal in the patients; 2h after LHRH-TRH the prolactin levels in women on carbamazepine were significantly higher than in the controls, but apart from this, no other differences were found. Baseline LH levels were raised in male patients and the response to LHRH-TRH was exaggerated in all patients on carbamazepine. FSH levels were normal throughout. The exaggerated LH response is consistent with primary hypogonadism caused by enhanced sex hormone metabolism, secondary to hepatic enzyme induction by the antiepileptic drugs.

Adult↗
PubMed1984

A clinical trial of single dose rectal and oral administration of diazepam for the prevention of serial seizures in adult epileptic patients.

The clinical anticonvulsant efficacy of single dose rectal and oral administration of diazepam 20 mg was examined in two double-blind placebo-controlled trials in adult epileptic patients. All subjects suffered from drug resistant epilepsy and frequently experienced serial seizures. Diazepam was administered rectally as a new experimental suppository formulation immediately after a seizure and was highly effective in preventing recurrent fits within a 24 h observation period (p less than 0.001). Pharmacokinetic studies revealed a wide range of serum diazepam concentrations 60 min after administration of the suppository (mean serum diazepam level 190 +/- 73 (SD ng/ml). In a similar study oral administration of diazepam 20 mg significantly reduced the incidence of serial seizures compared with a placebo (p less than 0.01) and the mean 60 min serum diazepam level was 273 +/- 190 (SD) ng/ml.

Administration, Oral↗
PubMed1984

Effect of meptazinol and ethanol on human psychomotor performance and mood ratings.

The effect of meptazinol and/or ethanol on human psychomotor performance and mood ratings has been investigated in 8 healthy volunteers in a double blind randomised study. Meptazinol (200 mg 3 hourly for 4 doses) or placebo were administered orally and ethanol (0.8 g/kg) or placebo were given 30 min after the last tablet. Peak saccadic velocity (PSV), saccade duration at 30 degrees of amplitude (SD), smooth pursuit velocity (SPV), critical flicker fusion threshold (CFF), choice reaction time (CRT) and visual analogue scales were assessed. PSV (p less than 0.01), SD (p less than 0.001) and SPV (p less than 0.01) were significantly impaired after ethanol, while CFF, CFT and visual analogue scales showed no significant effect. None of the tests was affected by the meptazinol treatment alone. No changes were observed in the ethanol-induced impairment of PSV, SD and SPV when meptazinol was given in combination with ethanol.

Adult↗
PubMed1983

Effect of a single oral dose of propranolol on essential tremor: a double-blind controlled study.

The effect of a single oral dose of propranolol (120 mg) on essential tremor was investigated in a double-blind, placebo-controlled study in 26 patients. Hand tremor was recorded by means of accelerometers, and its frequency and amplitude calculated by using spectrum analysis. Recordings were made before and 1 1/2 hours after drug or placebo administration. Pretreatment tremor ranged from 4.2 to 9.6 Hz (median, 6.9 Hz) in frequency and from 0.002 to 1.33 cm (median, 0.014 cm) in amplitude. Neither propranolol nor placebo affected the frequency of the underlying tremor. The amplitude of tremor was reduced by 43 +/- 11% (SEM) after propranolol (p less than 0.01) and by 12 +/- 8% after placebo (NS). The reduction observed after propranolol was significantly greater than that observed after placebo. The tremor response after propranolol correlated negatively with baseline frequency and positively with pretreatment amplitude, duration of tremor, and age of the patient. No significant relationships could be found between tremor response, serum propranolol levels, and degree of cardiac beta blockade as assessed by the inhibition of standing tachycardia. There was a clear tendency for patients with small tremor amplitude (less than 0.006 cm hand displacement) to show the least satisfactory response to propranolol. These results indicate that a single oral dose of propranolol is effective in producing a rapid and marked reduction of essential tremor. Measurement of pretreatment amplitude and frequency might be useful in predicting the therapeutic outcome in these patients.

Adult↗
PubMed1983

Specific oculomotor deficits after amylobarbitone.

Five healthy volunteers received a single oral dose of amylobarbitone sodium (200 mg) and placebo in a double blind randomized fashion. Peak velocity of horizontal saccadic eye movements, saccade duration and smooth pursuit velocity were measured at intervals up to 6 h after drug administration. The active treatment produced a statistically significant decrease of both saccadic and smooth pursuit eye velocity. The maximum effect was observed 2 h after drug administration. The effect on peak saccadic velocity was still statistically significant 6 h after treatment. The maximum impairment in eye movement performance ranged between 25 and 29%. These results demonstrate that both saccadic and smooth pursuit systems are unable to generate the required eye velocity under the influence of a therapeutic dose of amylobarbitone sodium.

Adult↗
PubMed1983

Effect of amphetamine on saccadic and smooth pursuit eye movements.

Healthy volunteers received single oral or intravenous doses of d-amphetamine sulphate (15 mg) and placebo in a double blind randomized design. Peak velocity of horizontal saccadic eye movements, saccade duration, saccade reaction time and smooth pursuit velocity were measured at intervals up to 1 h (IV) and 6 h (oral) after drug administration. Amphetamine produced no significant effect on saccadic and smooth-pursuit eye movements after oral administration. However, intravenous amphetamine abolished the effect of fatigue on saccadic movements and significantly (P less than 0.01) shortened saccadic reaction time.

Administration, Oral↗
PubMed1983

Comparison of assay methods used to measure antiepileptic drugs in plasma.

The various techniques used to measure the concentration of antiepileptic drugs in plasma have been compared using data from the HEATH-CONTROL external quality control scheme. Assay methods were categorized as gas-liquid chromatography with and without derivatization (GLC + D, GLC-ND), radio- and enzyme multiplied immunoassay (RIA, EMIT), thin-layer and high-pressure liquid chromatography (TLC, HPLC), and spectrophotometry and colourimetry. The accuracy of the methods was determined from differences of measurements from the levels of drugs spiked into the samples. Most methods significantly underestimated the spiked drug concentrations. Comparisons of assay precision were made with the standard deviation of measurements or from the performance of individual laboratories in a ranking procedure. Comparable significant differences were found in both analyses. RIA followed by GLC-ND were the least variable methods for phenytoin; EMIT and then GLC-ND were the best for both phenobarbitone and primidone. Spectrophotometric measurements of phenobarbitone were unacceptably variable. TLC and colourimetry performed well for carbamazepine, whereas the GLC methods were the most variable. HPLC topped the list for ethosuximide, whereas EMIT had difficulty with this drug. Methods used for valproic acid were similar in precision. GLC + D was consistently less effective for all drugs when compared with GLC-ND.

Anticonvulsants↗
PubMed1983

Rate of entrance of benzodiazepines into the brain determined by eye movement recording.

1 Peak saccadic velocity of horizontal eye movements, saccade duration at 30 degrees of amplitude and saccade reaction time were measured in six drug free male subjects. 2 In two separate experiments, intravenous doses of diazepam (5 mg), lorazepam (2 mg), chlordiazepoxide (25 mg) and placebo were given, and eye movement recordings were made before and at frequent intervals after drug administration. 3 All the benzodiazepines produced a significant impairment of peak saccadic velocity and saccade duration. Only lorazepam significantly affected saccade reaction time. 4 Time to achieve maximum effect was 10 min after diazepam, 29 min after lorazepam and 42 min after chlordiazepoxide.

Adult↗
PubMed1983

Benzodiazepines impair smooth pursuit eye movements.

Five healthy male volunteers received single oral doses of 10 mg diazepam, 20 mg temazepam and placebo, in a double-blind, randomised fashion. Smooth pursuit eye movement velocity and serum benzodiazepine concentration were measured before and after at 0.5,1,1.5,2,3,4,6,9 and 12 h after administration of the treatments. Significant decrease in smooth pursuit eye movement velocity as compared to placebo was observed between 0.5-2 h after temazepam, and between 1-2 h after diazepam. Smooth pursuit eye movement velocity was log-linearly correlated with serum temazepam and diazepam concentration. The results demonstrate the relationship between serum benzodiazepine concentration and its effect on an objective measure of oculomotor performance.

Adult↗
PubMed1983

Acute effects of intravenous phenytoin on the frequency of inter-ictal spikes in man.

Phenytoin was administered intravenously to six adult epileptic patients in doses ranging from 500--1000 mg (equivalent to 5.6 mg/kg--20 mg/kg body weight). A significant decrease in the frequency of inter-ictal spikes in the EEG was seen and this effect was most marked 10--20 min after the infusion, when the mean spike count was reduced to 27% (s.d. 17%) of the control (P less than 0.05). In one subject the decrease in inter-ictal spikes coincided with a decrease in fit frequency. Adverse reactions affecting the vestibular system occurred in three patients at doses of 15--20 mg/kg. No cardiovascular complications were observed in any subject. The overall results suggest that doses of 7.5--10 mg/kg would be sufficient to significantly reduce the frequency of inter-ictal spikes in the EEG.

Adult↗
PubMed1983

Antidepressant drugs, convulsions and epilepsy.

1 Evidence concerning the convulsant effects of non-monoamine oxidase inhibitor antidepressant drugs has been reviewed. 2 Mianserin is convulsant in therapeutic doses but seizures have not been reported following overdose. 3 The convulsant effects of mianserin are probably no greater than for other non-monoamine oxidase inhibitor antidepressant drugs. 4 Enzyme-inducing anti-epileptic drugs can reduce the peak plasma concentration of mianserin and shorten its elimination half-life, probably by inducing its metabolism.

Antidepressive Agents↗
PubMed1983

Effect of norethisterone on seizures associated with menstruation.

The effect of high and low doses of norethisterone on seizure frequency was studied in nine epileptic patients, aged 20-30 years. All patients satisfied the defined criteria of having catamenial exacerbation. The study was double blind, placebo controlled, and randomised. Each patient was followed through four menstrual cycles with each drug dose and also with placebo. The results of this study suggest that norethisterone is not effective in the control of seizures associated with the menstrual period.

Adult↗
PubMed1983

A controlled trial of cinromide.

A double-blind controlled trial of cinromide in 25 adult subjects with refractory epilepsy using the maximum tolerated dose showed that it possessed no significant antiepileptic properties.

Adolescent↗
PubMed1983

The response of essential tremor to propranolol: evaluation of clinical variables governing its efficacy on prolonged administration.

The factors influencing the response of essential tremor to prolonged administration of propranolol (120 mg daily for two weeks followed by 240 mg daily for a further two weeks) were investigated in a double-blind, cross-over, placebo-controlled study in 16 patients. Hand tremor was assessed by means of accelerometers with off-line computer analysis. Propranolol was found to be superior to placebo only at the higher dosage regimen (240 mg daily). At this dosage, the median reduction in tremor amplitude (as compared to the control value) was by 45%. The response to the drug (expressed as percentage change in tremor amplitude) was correlated positively with the control amplitude (rs = 0.71, p < 0.01) and negatively (but more weakly) with the control peak frequency of tremor (rs = -0.53, p < 0.05). In the patients with hand tremor greater than 6 x 10(-3) cm hand displacement the tremor amplitude was reduced by 65%, as compared to only 17% in patients whose tremor amplitude was below this limit. No statistically significant relationship could be found between percentage change in tremor amplitude and duration of the disorder, age of the patients, degree of cardiac beta-blockade or serum propranolol levels. The results suggest that patients with small tremor amplitude should not be treated with propranolol unless their tremor becomes severely aggravated under conditions of excessive adrenergic discharge.

Adult↗