Biomedical subjects
William P Leary
Publications and source records attributed to William P Leary.
Hypertension, diuretics, and uric acid.
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Pharmacokinetics and pharmacodynamics of intranasal insulin administered to patients with type 1 diabetes: a preliminary study.
BACKGROUND: The pharmacokinetics and pharmacodynamics of a Bentley Pharmaceuticals (Exeter, NH) proprietary insulin formulation designed for intranasal administration were studied in patients with type 1 diabetes, using subcutaneous insulin or placebo as comparator. METHODS: Seven fasting volunteer patients with type 1 diabetes (five men, two women; body mass index 23.54+/-1.32 kg/m2) received up to four doses of medication (placebo, subcutaneous insulin, or intranasal insulin) at least 3 days apart. Serum insulin and plasma glucose were measured in the 5-h period after dosing. RESULTS: The relative bioavailability of intranasal insulin compared with subcutaneous insulin was 16.6-19.8% over 2 h and 14.0-19.8% over 5 h. The formulation was generally well tolerated. At doses of 25 IU and above, a rise in serum insulin levels accompanied by a decrease in plasma glucose was seen. Peak insulin levels were generally attained in 15-20 min and remained elevated for approximately 1 h; the resultant effect upon glucose peaked at 40 min and waned 1.5-2 h post-dosing. The effect was dose related. Mean peak insulin levels increased with dose escalation. As reported in other insulin studies, the inter-individual responsiveness to insulin was variable. CONCLUSIONS: This intranasal formulation was generally well tolerated, and relatively well absorbed as demonstrated by a rapid rise in serum insulin level and concomitant reduction of plasma glucose levels.
Allopurinol or oxypurinol in heart failure therapy - a promising new development or end of story?
The plasma level of the uric acid is frequently elevated in heart failure, due to increased production and/or to reduced renal excretion of this antioxidant metabolite. The transformation of hypoxanthine to xanthine and the conversion of the latter into uric acid, which occur in purine catabolism, are catalysed by xanthine oxidoreductase. The constitutive xanthine dehydrogenase form of this enzyme generally uses NAD(+) as an electron acceptor, whereas the post-translational xanthine oxidase form uses molecular oxygen and yields four units of reactive oxygen species per unit of transformed substrate. Allopurinol and oxypurinol inhibit xanthine oxidoreductase and thus diminish the generation of reactive species and decrease plasma uric acid. In a recent study in patients with NHYA class II-III heart failure, add-on treatment with allopurinol 300 mg/day for 3 months lowered plasma uric acid but failed to improve laboratory exercise performance or the distance walked in 6 minutes. In another recent trial, which was carried out in patients with NHYA class III-IV heart failure, add-on treatment with oxypurinol 600 mg/day for 24 weeks decreased plasma uric acid concentration but did not change a composite of patient outcome and state. These results indicate that the reduction in plasma uric acid caused by allopurinol or oxypurinol does not benefit patients with heart failure. Moreover, the hypothesis that the diminution in the renal excretion of the antioxidant uric acid caused by diuretics may be salutary in cardiac failure is strengthened by the study results considered.
The aldosterone antagonist and facultative diuretic eplerenone: a critical review.
Eplerenone is a new aldosterone-receptor blocker that differs from spironolactone by virtue of higher selectivity for the aldosterone receptor. Therefore, eplerenone treatment is associated with comparative and absolute low incidences of gynecomastia, mastodynia, and abnormal vaginal bleeding. Similarly, a lower incidence of sexual impotence than that associated with spironolactone administration may be anticipated. Eplerenone and spironolactone increase natriuresis and cause renal retention of potassium when plasma aldosterone is high, i.e., both agents are facultative diuretics. Eplerenone reduces high blood pressure effectively. The results of a recent large study and an ensuing meta-analysis on antihypertensive treatment suggest that a diuretic should be the first-choice agent in most circumstances. Low-dose eplerenone combinations with a low-dose thiazide-type diuretic appear to be options worth investigating, since the overall cardiovascular benefit brought about by reducing blood pressure with the thiazide would be increased, inter alia, by the antikaliuretic action and by the blockade of extrarenal aldosterone receptors provoked by eplerenone. Eplerenone should replace spironolactone as a natriuretic and antikaliuretic in heart failure and as add-on treatment in severe systolic cardiac insufficiency, and it is indicated after an acute myocardial infarction complicated by left ventricular dysfunction and heart failure. The finding that hypertension control with diuretic-based pharmacotherapy results in better prevention of heart failure than pressure reduction with other drugs makes it pertinent to investigate whether diuretics in general, and eplerenone in particular, should constitute part of the initial pharmacotherapy for heart failure when there is no overt fluid retention and independent of the etiology. Eplerenone may cause hyperkalemia, and it might favor the development of metabolic acidosis or hyponatraemia in some circumstances.
The increase in serum uric acid induced by diuretics could be beneficial to cardiovascular prognosis in hypertension: a hypothesis.
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The ALLHAT and the cardioprotection conferred by diuretics in hypertensive patients: a connection with uric acid?
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