PubMed Health⌕ Search

Biomedical subjects

D B Frewin

Publications and source records attributed to D B Frewin.

At least 91 records · Page 5Linked to original sources
PubMed1979

Vascular effects of etilefrine. Further studies to substantiate the predominant indirect sympathomimetic action of this agent.

The suggested use of etilefrine in the treatment of patients with orthostatic hypotension is based on the premise that it has an action similar to that of noradrenaline (Miller, Wiener and Bloomfield, 1973). However, earlier work from this laboratory (Frost, Frewin and Gerke, 1977; Frost, Frewin, Gerke and Downey, 1978; Frost, Halloran, Frewin, Gerke and Downey, 1978) on blood vessels in the rat tail has suggested that the drug acts predominantly as an indirect sympathomimetic agent. The present study examined the action of etilefrine on the central artery of the rabbit ear. This vessel is known to have a rich sympathetic innervation (de la Lande, Frewin and Waterson, 1967) and has the added advantage that it can be surgically denervated. It therefore became possible to examine the effects of etilefrine on both normal and denervated arteries and to quantitate the extent to which the drug relied on the symphathetic nerves for its vasoconstrictor effects.

Animals↗
PubMed1979

Impairment of hepatic drug metabolism in alcoholics.

1 The effects of chronic ethanol intake on the elimination kinetics of antipyrine were determined in nineteen male alcoholic subjects with comparison made to fourteen male volunteers. 2 Half-lives were longer and clearance values less in the alcoholic group. 3 Significant rank correlations were found between half-life and clearance when compared with various biochemical parameters of liver function measured in the plasma of the alcoholics. 4 These results show that a significant proportion of the alcoholics studied had impaired hepatic drug metabolizing capacity and that the activity of hepatic microsomal enzymes may be related to the extent of ethanol induced liver damage in these subjects.

Adult↗
PubMed1979

Abdominal pain following intravenous benzyl penicillin administration.

The occurrence of abdominal pain (in three patients) and lower chest pain (in one patient) either during or immediately after the intravenous administration of high doses of benzyl penicillin is reported. All four patients were diagnosed as having bacterial endocarditis and had been receiving between 8 and 18 mega units of the drug per day for 2--3 weeks, when the symptoms were first noticed. A skin rash also appeared in each case, at this time. Both the rash and abdominal pain disappeared when an alternative antibiotic was substituted for the penicillin.

Abdomen↗
PubMed1979

Antiopyrine half-life as a measure of hepatic enzyme induction: clinical applications in a chronic epileptic population.

Quantitation of hepatic microsomal enzyme induction in epilepsy has a theoretical role in identifying patients at risk of metabolic bone disease, in assessing drug compliance and in predicting anticonvulsant dose/serum level relationships. The clinical usefulness of antipyrine half-life as a measure of enzyme induction in chronic epilepsy has been explored in this study. Mean antipyrine half-life in a control group (mean 10.7 hours SD 2.0) was significantly longer than in an epileptic group (mean 5.6 hours SD 2.3). Antipyrine t1/2 did not distinguish epileptics with osteomalacia from other epileptic patients and half-lives were similar in patients treated with phenytoin and a barbiturate to those in patients on phenytoin alone. No significant correlation was found between antipyrine half-life and phenytoin dose or between half-life and phenytoin level. In 5 patients with low serum levels of anticonvulsant, antipyrine kinetics suggested poor compliance in 3 and rapid hepatic phenytoin degradation in 2. This study suggests that measurement of antipyrine half-life may be useful in assessing drug compliance, but is not useful in predicting the onset of osteomalacia or dose/serum level relationships.

Adult↗
PubMed1978

Hypertension after ingestion of Trimolets.

A 21-year-old nurse presented with severe headache after ingesting one phenylpropanolamine (Trimolets) tablet. Examination revealed hypertension. Although no specific therapy was administered to the patient, her blood pressure normalized within a few hours of admission to hospital and has remained normal since. The patient declined rechallenge with the suspected drug.

Adult↗
PubMed1978

The effects of agents modifying sympathetic nerve function on the response of the isolated rat tail artery to etilefrine and tyramine.

The effects of etilefrine on the ventral caudal artery of the rat have been examined in the presence of agents modifying sympathetic nerve function. Catecholamine levels were also measured in adjacent segments of artery to those studied pharmacologically and an attempt made to relate vascular response to etilefrine (and tyramine) with catecholamine content. Both guanethidine and reserpine produced significant attenuation of the vascular effects of etilefrine and tyramine. Pre-treatment with a monoamine oxidase inhibitor caused an increase in tissue catecholamine levels but, paradoxically, depressed the vascular response to etilefrine. The significance of some of the findings in terms of an indirect component to etilefrine's action are discussed.

Animals↗
PubMed1978

The effect of irradiation and heat on the content of adrenaline in commercially manufactured local anaesthetic solutions--a pilot study.

Carpules of commercially available local anaesthetic solutions containing adrenaline have been exposed to varying conditions of heat, ultra-violet and infra-red light over a period of two months. The adrenaline content in the solutions was assessed by fluorometric assay both at the commencement of study and at regular intervals over the period of exposure. Infra-red light appeared to have little or no effect on the concentration of adrenaline, while ultra-violet light, either alone or in combination with infra-red light, caused the adrenaline levels to diminish rapidly. The results suggest that the ultra-violet component of light is probably responsible for the breakdown of catecholamines in local anaesthetic solutions when these solution are stored in areas exposed to sunlight.

Epinephrine↗
PubMed1978

The use of mixtures of octapressin and adrenaline in local anaesthetic solutions to obtain more effective vasoconstriction.

The synergistic effects of felypressin with adrenaline have been studied using the isolated central artery of the rabbit ear as a vascular model. Sub-constrictor doses of felypressin were shown to increase adrenaline's vasoconstrictor effect on this vessel. It is therefore suggested that a mixture of felypressin and adrenaline be used in local anaesthetic solutions in order to provide more effective vasoconstriction.

Anesthetics, Local↗
PubMed1978

The indirect sympathomimetic activity of etilefrine--a comparison with tyramine and ephedrine using [3H] noradrenaline.

The indirect sympathomimetic activity of etilefrine has been examined using the ventral caudal artery of the rat. This vessel has a rich sympathetic innervation and lends itself to studies on [3H]noradrenaline efflux from these sites. Etilefrine possessed significant indirect activity on the artery and this action, although less than that of tyramine, was equivalent to that caused by ephedrine. Pretreatment of the vessels with a mixture of iproniazid, doca, cocaine and UO521 (3',4'-dihydroxy-2-methyl propiophenone) significantly enhanced[3H]-noradrenaline efflux from the artery.

Animals↗
PubMed1978

Altered drug metabolism in anaesthetists exposed to volatile anaesthetic agents.

Antipyrine kinetics were measured on saliva in eight anaesthetists during a period when they were giving general anaesthetics and a period when they were working exclusively in intensive care. During the anaesthesia period there was a reduction in antipyrine half-life and the clearance of antipyrine increased. Analysis of the data in groups failed to detect these changes because of the wide variation in metabolism between subjects. Exposure to anaesthetic agents under non-scavenging operating theatre conditions appears to enhance hepatic metabolism.

Adult↗
PubMed1977

Semi-automated catecholamine assay.

Three semi-automated procedures are described for the estimation of the catecholamine contents of urine, tissue and plasma samples. The three procedures are based on the fluorometric tri-hydroxyindole assay which has been modified for automatic analysis. These techniques offer several advantages over currently available assays in that they are more convenient, provide for faster analysis rate and give increased sensitivity. The results of the present studies in which the catecholamine contents of urine, tissue and plasma samples were determined using the semi-automated assay provided a range of values which was identical to that obtained using other methods.

Adrenal Glands↗
PubMed1977

The effect of aspirin pretreatment on the sweating response of older female subjects.

Seven healthy female volunteers (aged 50 to 67 years) have been subjected to a thermal stress and their sweat rates evaluated using hygrosensors on five different locations on their body surface. It was found that the sweating rate was highest on the forehead in all but one of the subjects with the chest being the next most prominent site for the response. Five of the subjects were restudied after aspirin pretreatment. In the presence of this drug, resting body temperature was lowered, sweating occurred at a lower oral temperature and the mean sweating rate at a standardized body temperature was significantly higher. These findings are consistent with aspirin's known pharmacological actions, although in this study the increased sweating rate have been demonstrated in afebrile subjects.

Age Factors↗