摘要:

The effects of ouabain and furosemide on the unidirectional efflux of sodium and phosphate ions were studied in freshly drawn human red blood cells (RBCs). In the presence of physiologic concentrations of sodium and potassium the rate of sodium efflux was reduced by 74% due to ouabain sensitivity. Furosemide (1.0 mmol/l) reduced ouabain‐insensitive sodium transport rate by a further 50%. Thus, 13% of total sodium efflux was inhibited by furosemide when ouabain was present. In the absence of ouabain, however, furosemide inhibited 31% of total sodium transport, indicating that it also affected ouabain‐sensitive sodium efflux. Phosphate transfer of RBCs was almost 1.0 mmol/l RBCs per hour. Erythrocyte concentration of orthophosphate, however, was only 0.59 mmol/l RBCs. Organic phosphate esters must therefore have been cleaved to maintain constant phosphate elimination. The hydrolysis of adenosine triphosphate (ATP) by Na‐K‐ATPase might be involved because the phosphate transfer of almost 0.12 mmol/l RBCs per hour was ouabain sensitive. Furosemide reduced phosphate efflux by 50% due to reduction in passive permeability of the RBC membrane. Additional inhibition of any phosphate ester hydrolyzing enzymatic activity cannot, however, be excluded.Clinical Pharmacology and Therapeutics(1981)30, 709–717; doi:10.1038/clp

ISSN:0009-9236    

DOI:10.1038/clpt.1981.227

年代:1981

数据来源: WILEY

摘要:

We examined the effect of pergolide, a semi synthetic ergot alkaloid, alone or combined with carbidopa and levodopa (Sinemet), on the cardiac rhythm of 12 patients with Parkinson's disease. The patients were selected on the basis of severe Parkinson's disease and stable cardiac rhythm as determined by I to 5 days of Hoher monitoring. Monitoring was then carried out for an additional period of between 2 and 10 wk while the patients were on pergolide. Seven of the 12 patients had repetitive ventricular rhythms (RVRs). These were isolated, infrequent, and not associated with increases in premature ventricular contractions. The dose at which the RVRs occurred may be a function of the presence or absence of heart disease, but the significance of RVRs remains to be determined.Clinical Pharmacology and Therapeutics(1981)30, 718–723; doi:10.1038/clpt.1981.2

ISSN:0009-9236    

DOI:10.1038/clpt.1981.228

年代:1981

数据来源: WILEY

摘要:

After intravenous bolus injections of clonidine HCl (150 μg) to 12 patients with congestive heart failure, peak effects appeared in 5 to 20 min. Clonidine reduced heart rate from 94 ± 14 to 82 ± 14 bpm (x± SD, P<0.05), left ventricular filling pressure from 31 ± 5 to 23 ±5 mm Hg (P<0.001), mean systemic arterial pressure from 98 ± 13 to 82 ± 13 mm Hg (P<0.001), mean pulmonary artery pressure from 46 ± 6 to 38 ± 6 mm Hg (P<0.001), and right atrial pressure from 14 ± 5 to 11 ±5 mm Hg (P<0.05). Cardiac index increased from 1.6 ± 0.4 to 1.8 ± 0.6 l/min/m2(P<0.05) and stroke volume from 32 ± 10 to 43 ± 12 ml/beat (P<0.05). Systemic vascular resistance decreased from 2,342 ± 800 to 1,795 ± 345 dynes sec cm−3(P<0.05) and pulmonary vascular resistance from 365 ± 158 to 263 ± 114 dynes sec cm−3(P<0.05). We conclude that clonidine decreases heart rate and left ventricular preload and afterload in congestive heart failure.Clinical Pharmacology and Therapeutics(1981)30, 724–728;

ISSN:0009-9236    

DOI:10.1038/clpt.1981.229

年代:1981

数据来源: WILEY

摘要:

Analysis of sequential plasma samples in 14 hypertensive subjects receiving their usual oral dose of clonidine (0.1 to 0.6 mg twice daily) indicated that clonidine plasma concentration increased for the first 2 hr and then decreased and stabilized over the next 12 hr. Percent fall in diastolic blood pressure, but not side effects, correlated well with plasma concentration. Our study indicates a potential role for plasma clonidine determination in the treatment of patients with hypertension. It also demonstrates that clonidine can probably be given at 12‐hr intervals and be effective.Clinical Pharmacology and Therapeutics(1981)30, 729–734; doi:10.1038/clpt.1981

ISSN:0009-9236    

DOI:10.1038/clpt.1981.230

年代:1981

数据来源: WILEY

摘要:

To evaluate the effect of maturation on the renal disposition of digoxin, the ratio of digoxin clearance to creatinine clearance was determined in 35 patients who were 3 days to 79 yr old. All were at steady‐state levels for digoxin treatment. A mean ratio of 1.49 ± 0.67 (SD) was obtained in the group of prepubertal children and infants ≥2 mo of age. The mean ratio decreased to 0.82 ± 0.25 (SD) in the adult group; adults were defined as sexually mature adolescents or older (P<0.005). The decrease in net renal tubular secretion of digoxin appears to occur at puberty. This observation can provide one explanation for the apparently larger doses of digoxin required by infants and children than by adults. It may also represent a developmental change in renal tubular physiology with broader significance than for digoxin disposition alone.Clinical Pharmacology and Therapeutics(1981)30, 735–738; doi:10.1038/clpt.

ISSN:0009-9236    

DOI:10.1038/clpt.1981.231

年代:1981

数据来源: WILEY

摘要:

The effect of acebutolol as an antihypertensive beta receptor‐blocking drug was evaluated in 15 patients that remained hypertensive while on diuretics. Observations were made in a small randomized double‐blind trial in which the drug was compared to placebo and subsequently during a single‐blind phase when the drug was given to those who had not responded to placebo. The dose range for acebutolol was 200 to 600 mg twice daily. Pretreatment plasma renin activity (PRA) and the response to intravenous saralasin infusion were assessed as predictors of the antihypertensive effect of acebutolol. None of six patients receiving placebo had a response of goal blood pressure or below; six of nine receiving acebutolol did respond (P<0.01). Acebutolol treatment induced reduction in diastolic pressure, heart rate, and PRA during the double‐blind phase and a sustained therapeutic response over 18 wk in subjects pooled from both phases of the study. There were no significant correlations between pretreatment PRA, In PRA, or the response to saralasin, and the arterial pressure response to acebutolol therapy. Our data indicate that acebutolol is effective in diuretic‐resistant hypertensive patients and that indices of the renin‐angiotensin system are not predictors of the therapeutic response.Clinical Pharmacology and Therapeutics(1981)30, 739–744; doi:10.1038

ISSN:0009-9236    

DOI:10.1038/clpt.1981.232

年代:1981

数据来源: WILEY

摘要:

We evaluated changes in propranolol plasma levels before, during, and after cardiopulmonary bypass (CPB). Two groups of patients were studied, all of whom had been on long‐term propranolol and had received their last oral dose 10 to 15 hr before surgery. Approximately 100 min before CPB began group 1 patients (n = 7) received 0.1 mglkg propranolol intravenously while group 11 patients (n = 7) received a placebo. Before CPB the plasma propranolol levels fell in accordance with published descriptions for nonsurgical patients receiving oral and intravenous propranolol. Thereafter, the changes in the plasma levels were much the same in both groups. With the onset of CPB, the plasma levels decreased by approximately 50%. There was an insignificant fall in plasma levels during CPB, but the most interesting observation was made after: in each patient, the plasma levels obtained 5, 60, 120, and 240 min after CPB were higher than the last level during CPB. Mean plasma levels did not decline in either group during the 4‐hr period. Although the reason for the sustained rise in the propranolol levels after CPB is not known, we suggest that it is due to the redistribution of propranolol from the lungs to the plasma coupled with reduction in hepatic elimination.Clinical Pharmacology and Therapeutics(1981)30, 745–751; doi:10.1038/clpt.19

ISSN:0009-9236    

DOI:10.1038/clpt.1981.233

年代:1981

数据来源: WILEY

摘要:

The efficacy, safety, and tolerability of lofexidine, a centrally acting imidazoline derivative, were compared to that of clonidine in a randomized double‐blind trial in 28 patients with moderate essential hypertension. The study consisted of a washout phase, a placebo phase, a drug titration phase (0.2 to 1.6 mglday, with hydrochlorothiazide added at 0.4 mg daily for supine and erect diastolic blood pressure above 90 mm Hg), and a maintenance phase lasting 3 mo. During the titration phase supine systolic and diastolic pressures fell in lofexidine patients from 143 ± 4198 ± 3 to 122 ± 3181 ± 2 mm Hg and in clonidine patients from 154 ± 61101 ± 2 to 124 ± 4/81 ± 2 mm Hg (P<0.01), and erect systolic and diastolic pressures fell in lofexidine patients from 143 ± 31105 ±2 to 116 ± 3185 ± 2 mm Hg and in clonidine patients from 156 ± 6/104 + 2 to 117 ± 4/82 ± 2 mm Hg (P<0.01). Maximal doses of lofexidine and clonidine in combination with hydrochlorothiazide had equivalent antihypertensive effects, but when the effects of lofexidine and clonidine were compared at each dose level, larger doses of lofexidine were needed to control blood pressure. There was no change in heart rate in lofexidine patients in either the supine or erect position during the titration phase but heart rate fell in the clonidine patients (P<0.05) over the same period. Dry mouth and drowsiness were reported in both groups but were both less frequent and less severe in the lofexidine group than the clonidine group.Clinical Pharmacology and Therapeutics(1981)30, 752–757; doi:10

ISSN:0009-9236    

DOI:10.1038/clpt.1981.234

年代:1981

数据来源: WILEY

摘要:

Propranolol, 20 mg, was given orally four times daily for 5 days and placebo four times daily for 5 days in a randomized, double‐blind fashion to nine healthy subjects. At the beginning of the study and on the last day of each medication pulse rate, blood pressure, airways resistance, maximum expiratory flow versus volume (using air and using 80% helium and 20% oxygen), spirometry before and after inhaled isoproterenol, and ventilatory and occlusion pressure responses to rebreathing carbon dioxide were measured. Results were compared by the Wilcoxon signed‐rank test. Propranolol was associated with decreases in pulse rate (P = 0.002), systolic blood pressure (P = 0.024), and diastolic blood pressure (P = 0.027). There were no differences in airway resistance or the change of expiratory flow with helium‐oxygen. Propranolol did not alter the preisoproterenol spirometry values but did reduce the response to isoproterenol. There were decreases in ventilatory responses (P = 0.004) and occlusion pressure responses (P = 0.006) at an end‐tidal carbon dioxide of 60 mm Hg. Propranolol's beta‐adrenergic blockade supresses central ventilatory response to carbon dioxide.Clinical Pharmacology and Therapeutics(1981)30, 758–764; doi:10.1038/c

ISSN:0009-9236    

DOI:10.1038/clpt.1981.235

年代:1981

数据来源: WILEY

摘要:

The short and long‐term antihypertensive action of timolol, a beta blocker, was assessed in 36 mild hypertensives in a 32‐wk, double‐blind, placebo‐controlled study followed by an additional 96 wk of timolol in 17 responders. Diastolic blood pressure (DBP) and heart rate (HR) declined during the first phase from 103 to 93 mm Hg and from 73 to 61 bpm (P<0.01) but there was no change in systolic blood pressure (SBP). The initial hypotensive responses continued in 17 long‐term timolol subjects (DBP 89 mm Hg at 32 wk and 88 mm Hg at 96 wk [NS] and HR 62 and 65 bpm [MS],). Although stimulated plasma renin activity in the entire group decreased from 1.08 to 0.28 nglmllhr (P<0.001), blood pressure reduction did not correlate with this decline (r = 0.29) or with serum timolol level (r = 0.29). In 20 patients who underwent treadmill exercise evaluation, timolol limited exercise HR and duration and work capacity but peak SBP was not altered. Thus, timolol is effective in reducing mild high blood pressure during short‐term therapy and in maintaining this effect over the long term in responsive subjects. It is therefore potentially useful in chronic essential hypertension.Clinical Pharmacology and Therapeutics(1981)30, 765–772; doi:10.1038

ISSN:0009-9236    

DOI:10.1038/clpt.1981.236

年代:1981

数据来源: WILEY