Rifampicin and vitamin D metabolism.

A 2-wk course of rifampicin orally (600 mg/day) in 8 male subjects resulted in a consistent fall in plasma 25-hydroxycholecalciferol (25-OHD) levels of around 70%, accompanied by increased oxidation of antipyrine and 6 beta-hydroxycortisol (indicative of hepatic enzyme induction). Plasma levels of 1,25-dihydroxycholecalciferol, parathyroid hormone, and calcitonin were not altered. The fall in 25-OHD may represent the earliest lesion of drug-induced osteomalacia.

Plasma levodopa, dopamine and therapeutic response following levodopa therapy of Parkinsonian patients.

In a double blind placebo controlled study of 6 Parkinsonian patients given a single dose of oral levodopa, the plasma levodopa and dopamine as measured by a radioenzymatic method both correlated with clinical improvement. There was a closer correlation with plasma dopamine than with plasma levodopa and it is proposed that peripheral decarboxylation may reflect central decarboxylation.

Human lung adrenoreceptors studied by radioligand binding.

1. Direct radioligand-binding techniques have been used to characterize and quantify adrenoreceptors in human peripheral lung tissue removed at thoracotomy from ten patients, nine of whom had evidence of obstructive airways disease. 2.

Hydralazine-induced systemic lupus erythematosus: influence of HLA-DR and sex on susceptibility.

26 patients with systemic lupus erythematosus (SLE) induced by treatment with the antihypertensive drug hydralazine were investigated to determine if predisposition to the toxic effect was associated with an HLA-DR antigen. 25 of the 26 patients were slow acetylators. The group was compared with three others (1) 113 healthy subjects, untested for acetylator phenotype, (2) 16 slow-acetylator hypertensive patients treated with hydralazine for more than a year without developing SLE, and (3) 20 patients with idiopathic SLE.

Antipyrene clearance in Indian villagers.

1 Antipyrine clearance has been measured using saliva samples in 50 Maharashtrans from a village to the north of Bombay. 2 All subjects were very lean and were also anaemic probably as a result of hookworm infestation. 3 Antipyrine clearance was 36% faster than in White Londoners studied previously and more than twice as fast as in Asian immigrants living in London.

Effect of propranolol on plasma norepinephrine during sodium nitroprusside-induced hypotension.

The possibility of an action of propranolol which reduces traffic in the sympathetic nervous system and/or reduces release of norepinephrine at sympathetic nerve endings has been investigated in normal subjects. Plasma norephinephrine was measured in resting supine subjects before and during infusions of sodium nitroprusside which reduced the systolic blood pressure by approximately 10 and later by 20 mm Hg. In 5 subjects these observations were repeated 2 hr after a single 200-mg oral dose of propranolol and in 3 they were repeated after 2 to 8 wk of propranolol 320 mg twice daily.

The biochemical diagnosis, localization and follow up of phaeochromocytoma: the role of plasma and urinary catecholamine measurements.

The diagnosis of phaeochromocytoma is dependent on combined biochemical and radiological investigation, the biochemical studies being performed initially and followed later by both non-invasive and invasive radiological techniques. In 23 patients studied, a selection of biochemical studies allowed diagnosis and accurate localization of phaeochromocytoma in 16. In some patients, tumour localization was confirmed by radiographic methods.

Long-term antihypertensive drug treatment and blood pressure control in three hospital hypertension clinics.

Prescribing patterns and blood pressure control have been studied in 1101 patients treated at three specialist hypertension clinics in Britain. Seventy-four per cent of the patients were already receiving treatment at the time they were referred by their general practitioners. Though the initial improvement in blood pressure control was satisfactory, there was often some deterioration of control over the long term.

Single-dose captopril administration in DOCA/salt rats: reduction of hypotensive effect by indomethacin.

The effect of an oral angiotensin I converting enzyme inhibitor, SQ 14225 (Captopril) on blood pressure and plasma renin activity (PRA) was studied in deoxycorticosterone-salt (DOCA/salt) hypertensive rats. Intraperitoneal (ip) injection of captopril (1 mg/kg) produced a significant fall in systolic blood pressure (23.4 +/- 5.

Centrally acting drugs in antihypertensive therapy.

The brain plays an important role in the regulation of blood pressure. Noradrenaline-containing cell bodies are present in several areas of the medulla. The nucleus of the solitary tract, an important centre for regulating baroreceptor and chemoreceptor reflexes, has a particularly rich innervation with adrenergic nerve endings.