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Biomedical subjects

J W Paterson

Publications and source records attributed to J W Paterson.

At least 73 records · Page 4Linked to original sources
PubMed1978

Antiarrhythmic potency of procainamide and N-acetylprocainamide in rabbits.

The antiarrhythmic potency of procainamide (PA) and N-acetylprocainamide (NAPA) has been investigated in rabbits using isolated atrial preparations and ouabain-induced ventricular fibrillation in vivo. At concentrations in the range 3 x 10(-5) to 1 x 10(-3) M, both PA and NAPA decreased the maximum following frequency (MFF) of isolated atria. The dose--response curves were not parallel but at a concentration of 10(-3) M, NAPA had only one tenth of the potency of PA. Threshold level voltage of the atria were increased by PA but NAPA had no significant effect on this parameter. When atria were preincubated with NAPA (1.6 x 10(-4) or 8.0 x 10(-4) M), the dose--response curve for PA on MFF was displaced to the right. Pretreatment of anaesthetised rabbits with either PA (25 mg/kg i.v.) or NAPA (75 mg/kg i.v.) prolonged the time to onset of ouabain-induced ventricular fibrillation. NAPA (25 mg/kg) did not affect the response to PA (25 mg/kg). The data support the view that NAPA is less potent than PA and suggest that, under certain circumstances, NAPA may antagonise the actions of PA.

Animals↗
PubMed1978

A comparison of salbutamol given by pressure-packed aerosol or nebulization via IPPB in acute asthma.

Salbutamol was given by pressure-packed aerosol or nebulizer via IPPB to patients with acute asthma to compare the effectiveness of these methods of inhalation. The results show that both methods produce significant bronchodilatation even in patients admitted with moderately severe asthma (FEV1 about 38% predicted) but a slightly greater improvement may be achieved by IPPB nebulization. Our findings indicate that supervised inhalation of a pressure-packed aerosol of salbutamol may be useful for the initial treatment of asthmatic attacks but confirm the marginal advantage of IPPB nebulization, which should be reserved for patients unable to inhale from a pressure-packed aerosol or failing to respond to its treatment.

Acute Disease↗
PubMed1978

Mechanism of the hypertensive effect of droperidol in pheochromocytoma.

Droperidol is used in the anaesthetic management of pheochromocytoma because of its sedative, anti-dysrhythmic and alpha-adrenoreceptor blocking properties. However, droperidol when used in pheochromocytoma, has been reported to produce a paradoxical hypertensive response. In vitro experiments with perfused rabbit ear arteries using a histochemical fluorescence technique, showed droperidol to be an inhibitor of noradrenaline uptake into sympathetic nerve endings, and this uptake inhibition was dose related. The uptake inhibition effect did not, however, produce pressor changes in experiments simulating pheochromocytoma in cats. The hypertensive response to droperidol may be due to blockade of presynaptic alpha-adrenoreceptors and this possible mechanism of action is discussed.

Adrenal Gland Neoplasms↗
PubMed1977

Plasma prednisolone levels in man following administration in plain and enteric-coated forms.

1 Prednisolone plasma levels were measured in seven patients by a competitive protein binding method after administration of prednisolone (20 mg) by mouth as plain or enteric-coated tablets. 2 The mean peak plasma prednisolone concentration after the enteric-coated preparation, 199 ng ml-1, was significantly lower than after the plain tablet, 268 ng ml-1, and occurred later, at 4.69 h compared with 1.72 h. The bioavailability of the two preparations was similar. 3 It is concluded that, although the plasma concentration versus time profiles are different, the absorption of prednisolone from plain and enteric-coated preparations is equal.

Humans↗
PubMed1977

The absorption and elimination of ICI 74,917 in man.

1 The pharmacokinetics of ICI 74,917 were studied in both asthmatic patients and normal volunteers. 2 The tritiated compound was administered to the lungs by inhalation from an aerosol and a bronchoscope, and by intravenous, oral and buccal routes. Radioactivity was measured in plasma, urine, faeces, sputum and exhaled air. 3 After bronchoscopic administration 63% of the available dose was absorbed; after aerosol administration 8% was absorbed from the lung and more than 50% swallowed. 5 Intravenous studies indicated that the drug is excreted in the bile and urine in the ratio 2:1. 5 Minimal oral and no buccal absorption occurred. 6 There was no evidence of tritium exchange or drug metabolism. 7 The mean terminal half-life following administration by all route was 16.1 hours. However, the majority of the dose was rapidly excreted. 8 Aerosol administration is the method of choice for the clinical use of ICI 74,917.

Absorption↗
PubMed1976

Plasma prednisolone levels after administration of prednisolone-21-phosphate as a retention enema in colitis.

A competitive protein-binding assay was used to measure plasma prednisolone levels after administration of prednisolone-21-phosphate retention enemas to seven patients with colitis. Prednisolone appeared in the plasma of all patients after the enema, and concentrations rose to a peak within three hours. In five of the patients plasma prednisolone levels were also measured after the same dose of prednisolone by mouth. Although in individual patients the plasma levels achieved by enema were often quite different from those achieved by mouth, overall the levels achieved by each mode of administration were of a similar order. These findings suggest that 20 mg prednisolone given by retention enema may well exert a systemic effect.

Adult↗
PubMed1976

The pharmacokinetics of ephedrine after oral dosage in asthmatics receiving acute and chronic treatment.

1 Ephedrine plasma levels have been measured in ten asthmatic patients given a singel dose of ephedrine hydrochloride (22 mg) along and in combination with theophylline and a barbiturate. 2 Pharmacokinetic assessment of the data indicated no significant intra-subject changes in kinetic parameters before or after chronic treatment with ephedrine HCl (11 mg three times a day) alone or in combination. 3 Tolerance to these therapeutic doses, if it occurs, is therefore not disposition-related but rather to pharmacodynamic changes.

Administration, Oral↗
PubMed1975

Potassium supplements in patients treated with corticosteroids.

1. Preliminary studies are reported on 8 patients with lung disease given prednisone both with and without potassium supplements. 2. There were no abnormalities of plasma potassium but there was a relationship between the dose of prednisone and the urinary excretion of potassium whilst off supplements: higher doses were associated with increased potassium excretion. 3. Patients who had been on treatment for a short period retained more of their supplements than did those who had been on treatment for several years. 4. It is suggested that with prolonged treatment control of potassium homeostasis may be altered, and that more detailed metabolic studies should be carried out.

Adult↗
PubMed1975

Patterns of response to isoprenaline in asthmatic patients.

Six asthmatic patients whose airway obstruction improved significantly during a trial of prednisone have been studied in detail. Serial measurements of forced expiratory volume in 1 second (FEV1) were made at specific times each day before and after isoprenaline, for 8 days. Peak response was at 5 minutes in the majority of tests. In contrast to previous studies no clear pattern of response emerged in relation either to type of asthma, length of history or initial FEV1.

Adult↗
PubMed1975

Effect of intravenous injection of salbutamol in asthma.

The effect of i.v. salbutamol was compared with aerosol salbutamol in ten asthmatic patients. 2 A cumulative dose of salbutamol (300 mug) given in three separate injections over 45 min resulted in a mean increase in peak expiratory flow rate (PEFR) of 38.3% and FEV1 of 36%. 3 There was no significant difference in degree of bronchodilatation to the same dose of salbutamol administered intravenously or by aerosol. 4 Palpitations, tremor, and postural hypotension were common when the drug was injected intravenously over one minute, but did not occur after aerosol administration. 5 It is suggested that sulbutamol by intravenous injection is a useful addition to the treatment of acute asthma.

Adult↗
PubMed1975

The acute and chronic bronchodilator effects of ephedrine in asthmatic patients.

In eight asthmatic patients, there was no change in the bronchodilator response to a single dose of ephedrine (22 mg) given alone or in a compound tablet, after treatment with ephedrine (11 mg three times a day) or one tablet three times a day for 2 weeks. 2 There was no deterioration in lung function during the 2 week treatment period with either ephedrine or the compound tablet. 3 An inter-patient variation was noted in the plasma ephedrine concentraition required for bronchodilatation. 4 The half-life of theophylline did not change after chronic treatment with the tablets, one three times a day for 2 weeks.

Administration, Oral↗
PubMed1975

Measurement of plasma prednisolone in man.

1. A modification of the competitive protein binding assay for prednisolone described by English, Chakraborty & Marks (1974) is presented. 2. Addition of pg quantities of [3H]-prednisolone following oral dosage with prednisone or prednisolone. 3. Mean plasma half-life and peak plasma concentrations in patients with respiratory disease seen following prednisolone administration agree well with previous studies in healthy volunteers performed by other workers using competitive protein binding and radioimmunoassay techniques. 4. A considerable inter-patient variation in bioavailability after a standard dose of prednisolone (20 mg) was noted.

Administration, Oral↗
PubMed1975

Interaction of corticosteroids and catecholamines in the treatment of asthma.

Twelve patients with airways obstruction (due to asthma and/or chronic bronchitis) were given a trial of prednisone therapy to assess reversibility. Six asthmatic patients responded well but no predictive criteria were found. In three patients improvement in forced expiratory volume in 1 second (FEV1) was detectable at 6 hours but not at 3 hours. One patient took 36 hours to show any sign of improvement. None of the patients who improved reached their peak FEV1 before six days treatment with prednisone, which suggests that a 'trial of steroids' should last for at least one week. Potentiation, as measured by either a greater peak rise or a more sustained increase in FEV1 after isoprenaline, was observed in five of the six asthmatic patients responding to steroids. It is concluded that potentiation of catecholmines is one of the mechanisms by which corticosteroids may act in asthma.

Adult↗