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Biomedical subjects

C J Roberts

Publications and source records attributed to C J Roberts.

At least 235 records · Page 13Linked to original sources
PubMed1978

Antipyrine disposition and liver size in the elderly.

This study has examined the contribution of decrease in liver size to the decline in drug metabolising capacity which occurs with ageing. Liver volume and antipyrine kinetics were measured in two groups of healthy individuals aged 20 to 29 years and 75 to 86 years and in a group of hospitalised patients aged 70 to 89 years. Liver volume was reduced in both groups of elderly people compared to the young group. Antipyrine plasma half-life was prolonged and antipyrine clearance was reduced in the group of elderly normal individuals. In this group the index--antipyrine clearance per unit liver volume--was also reduced in comparison to that of the young group. Measurements of antipyrine elimination in the hospitalised elderly group did not differ significantly from those in the young group. It is concluded that both decreased liver mass and decreased hepatic enzyme activity contribute to the impairment of drug oxidation which occurs in the elderly and which may warrant a reduction in dosage of some drugs. However, differences have been demonstrated between groups of elderly people suggesting that under certain circumstances standard doses of such drugs may be normally tolerated.

Adult↗
PubMed1978

Decreased first-pass metabolism of labetalol in chronic liver disease.

The effect of chronic liver disease on the rate of elimination and extent of "first-pass" metabolism of labetalol was studied. Pharmacokinetic measurements were made after both oral and intravenous administration to seven healthy subjects and to 10 patients with chronic liver disease. Plasma half life was similar in the two groups. Plasma concentrations were considerably higher in the patients than in the healthy subjects after oral administration but similar after intravenous injection. Thus the bioavailability of labetalol was increased in liver disease due to reduced first-pass metabolism. Bioavailability in the group of patients correlated negatively with serum albumin concentration. There were falls in supine heart rate and blood pressure which tended to be greater after oral administration in the patients with liver disease, suggesting an exaggerated response related to the increased bioavailability. Oral dosage requirements of labetalol and possibly other drugs susceptible to first-pass metabolism are reduced in the presence of liver disease.

Administration, Oral↗
PubMed1978

Effects of piretanide, bumetanide and frusemide on electrolyte and urate excretion in normal subjects.

1. The pharmacological actions of a new short acting loop diuretic were investigated in nine healthy male subjects and compared with those of frusemide and bumetanide. Subjects received 6 mg piretanide/day, 40 mg frusemide/day or 1 mg bumetanide/day for a period of 1 week. 2. Comparison of effects following the first dose administered showed that 6 mg piretanide is of similar potency to 40 mg frusemide in terms of diuresis, natriuresis and kaliuresis but is less potent than 1 mg bumetanide. 3. All three diuretics caused a decrease in urate excretion and a rise in serum uric acid. 4. Piretanide was well tolerated. Further investigation is required to ascertain what clinical advantage it offers over frusemide and bumetanide.

Adult↗
PubMed1978

The features of hepatic enzyme induction with glutethimide in man.

1 Sequential measurements of D-glucaric acid excretion were made in six healthy volunteers before, during and after 3 weeks' daily medication with glutethimide 500 mg. 2 There was a rapid rise in D-glucaric acid excretion within 2 days of starting medication and a rapid decline when it was stopped. 3 Antipyrine clearance and indocyanine green clearance were measured before and at the end of the 3 weeks' medication. 4 There was a 55% increase in antipyrine clearance but no change in indocyanine green clearance. 5 There was no correlation between antipyrine clearance and D-glucaric acid excretion. 6 Glutethimide causes rapid enzyme induction in man without concomitant rise in hepatic blood flow.

Antipyrine↗
PubMed1977

Spina bifida and anencephaly: are miscarriages a possible cause?

The marriage-to-conception interval in 151 pregnancies producing infants with anencephaly or spina bifida was not significantly different from that in 218 pregnancies resulting in normal infants. Significantly more miscarriages occurred before than after the birth of 285 infants with anencephaly or spina bifida, but in 133 controls no before-after difference was observed. These observations seem to favour the idea that miscarriages are a manifestation rather than a cause of anencephaly and spina bifida.

Abortion, Spontaneous↗
PubMed1976

Prospective comparison of double-contrast barium meal examination and fibreoptic endoscopy in acute upper gastrointestinal haemorrhage.

Fibre-optic endoscopy was compared prospectively with double-contrast radiology in 53 consecutive patients admitted with acute gastrointestinal haemorrhage. The bleeding site was correctly identified by endoscopy in 94% of patients and the final diagnosis was correctly given in 89%. The corresponding figures with radiology were 83% and 74%. Among the 50 patients with a final diagnosis of a bleeding site in the upper gastrointestinal tract endoscopy indicated the site of bleeding in all and radiology indicated it in 88%. Both investigations were well tolerated by patients. Endoscopy is the investigation of choice, but when it is not available double-contrast radiology will show the site of bleeding in 80-90% of patients.

Aged↗
PubMed1976

Raynaud's phenomenon as side effect of beta-blockers in hypertension.

A series of 102 hypertensive patients were assessed for the frequency of symptoms of Raynaud's phenomenon and absent peripheral pulses. Out of 21 patients receiving methyldopa alone only one had cold hands and feet whereas among patients on beta-blockers the incidence was 50%. The frequency of both symptoms and absent pulses was highest in patients taking propranolol compared with those taking atenolol or oxprenolol. Patients without a foot pulse were much more likely to have cold hands. A change from propranolol to oxprenolol in some symptomatic patients resulted in improvement. In two patients the skin temperature fell after an 80-mg dose of propranolol. The mechanism by which beta-blockers induce Raynaud's phenomenon is still not clear.

Adrenergic beta-Antagonists↗