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Biomedical subjects

B J Materson

Publications and source records attributed to B J Materson.

At least 91 records · Page 5Linked to original sources
PubMed1984

Potassium and diuretic-induced ventricular arrhythmias in ambulatory hypertensive patients.

We studied 17 hypertensive men to determine the relationship of diuretic-induced hypokalemia to ventricular ectopic activity ( VEA ). Blood values and 24-hour ambulatory ECG monitoring were done at baseline, after diuretic and after serum potassium normalization. Two subgroups of patients were identified: group A patients were older (63.0 vs. 53.8 years) and had clinical evidence of organic heart disease compared to group B. Group A had increased frequency and complexity of VEA with diuretic which reverted to baseline after potassium normalization. Group B had no changes. Serum and intra-red blood cell potassium decrements were equal in both groups. We conclude that clinical in addition to laboratory observation should be used to identify those hypertensive patients most susceptible to diuretic-induced VEA and their serum potassium level should be normalized in order to minimize this complication.

Adult↗
PubMed1983

Insights into intrarenal sites and mechanisms of action of diuretic agents.

Effective diuresis requires both sufficient glomerular filtrate and adequate delivery of the diuretic drug to the lumen of the renal tubule. Diuretics will not "force open" the kidney. Diuretics that work primarily in the proximal tubule include osmotic diuretics (e.g., mannitol), diuretics that interfere with the adenyl cyclase system (e.g., xanthines), and those which inhibit carbonic anhydrase (e.g., acetazolamide). Some thiazide and thiazide-like diuretics have a secondary site of action in the proximal tubule based on either carbonic anhydrase inhibition or other mechanisms, such as inhibition of sodium phosphate reabsorption. The diuretics that work primarily in the medullary diluting segment of the loop of Henle, furosemide and ethacrynic acid, block the active reabsorption of chloride and interfere with the tubular reabsorption of free water. The exact mechanism remains unknown. These diuretics tend to have a "high ceiling," to be potent and rapidly acting, and to have a short duration of effect. They are excellent for the treatment of severe fluid overload or pulmonary edema but are not ideal for the treatment of uncomplicated hypertension. Furosemide is a sulfonamide derivative; ethacrynic acid can be used in patients who are allergic to sulfa drugs. Diuretics that work primarily in the cortical diluting segment include the thiazides and thiazide-like drugs. They inhibit sodium transport by an undetermined mechanism. Most of them seem to reach a dose-response plateau beyond which little additional effect is gained by increasing the dose. Most of them appear to lose efficacy as the glomerular filtration rate decreases, except for metolazone and indapamide. The thiazides are most commonly used to treat hypertension. Diuretics that work primarily in the distal tubule and collecting tubule include the aldosterone inhibitor spironolactone and two drugs that impair tubular reabsorption of sodium by direct action, triamterene and amiloride. These drugs are primarily used for their potassium-sparing effect.

Animals↗
PubMed1983

Comparison of propranolol or hydrochlorothiazide alone for treatment of hypertension. III. Evaluation of the renin-angiotensin system.

In this study, the relation between renin activity and therapeutic response to hydrochlorothiazide or propranolol was studied. Patients with a diastolic blood pressure of 95 to 114 mm Hg were treated with propranolol (40 to 320 mg twice daily) or hydrochlorothiazide (25 to 100 mg twice daily). The initial renin profiles were: low, 56 percent (n = 300); normal, 33 percent (n = 174); high, 11 percent (n = 60). A greater incidence of low and fewer high renin profiles (p less than 0.001) were observed in blacks. After furosemide administration (40 mg intravenously), 55 percent of patients (n = 291) had a low renin response and 45 percent (n = 240) had a normal renin response. No correlation between renin profile and renin response was observed, although low renin response and low renin profile occurred more frequently in older patients. Hydrochlorothiazide administration resulted in a greater decrement in diastolic blood pressure (p less than 0.05) in the total group. Irrespective of renin activity, both hydrochlorothiazide and propranolol reduced diastolic blood pressure. When renin profile was considered, no significant variation in response to hydrochlorothiazide therapy was observed, and there was a greater reduction in diastolic blood pressure in the patients with a high renin profile receiving propranolol. In comparing therapeutic response, patients with a low renin profile had a better response to hydrochlorothiazide, and propranolol was more effective in patients with a high renin profile. The anticipated effect of therapy on plasma renin activity was observed. Although these results are consistent with a volume-vasoconstrictor analysis of hypertension, the results of therapy could not have been prejudged from renin profile or responsivity. The slight differences observed do not warrant the expense of renin determinations when a simple determination of therapeutic response is sufficient.

Blood Pressure↗
PubMed1983

Slow-release oxprenolol compared with oxprenolol in hypertensive patients: a multicenter clinical trial.

Oxprenolol (OX) is a nonselective, beta-adrenergic blocking agent with intrinsic sympathomimetic activity. We studied 178 patients in five centers to determine whether a polymer-matrix-based, slow-release preparation of oxprenolol (SR-OX) given once daily was as effective as the standard preparation given twice daily for the treatment of patients with mild to moderate hypertension. After a placebo washout phase, patients were treated with OX until blood pressure was controlled. They were then randomized in a double-blind fashion to continue the same dose, given as either OX bid or SR-OX qd with a placebo as the second dose. All patients took hydrochlorothiazide 50-100 mg/d throughout the study. Blood pressure was reduced 23/15 mm Hg (p less than 0.001) and pulse 8 beats/min in the SR-OX group (n = 67) and 24/17 mm Hg (p less than 0.001) and 8 beats/min in the OX group (n = 72) by titrating standard OX. After randomization to SR-OX or OX, there were no further changes over six weeks. Home-determined blood pressures showed no loss of control in the evening. There were no unexpected adverse effects. We conclude that SR-OX given once daily is as effective as OX given twice daily for the treatment of hypertension.

Adult↗
PubMed1983

Angiotensin converting enzyme inhibitors in the treatment of hypertension.

Converting enzyme inhibitors appear to be a safe and effective class of drug for treating the entire spectrum of hypertension, from very mild to severe. For the vast majority of patients who do not experience adverse side effects, these drugs appear to be remarkably well tolerated and are without the adverse metabolic and depressive effects associated with other antihypertensive drugs. Many patients report an enhanced feeling of well-being and may even experience euphoria. Whenever possible, CEIs should be used in the lowest possible effective dose in order to achieve maximum therapeutic benefit with a minimum or complete absence of adverse effects.

Antihypertensive Agents↗
PubMed1980

Laxative abuse syndrome.

Laxative abuse syndrome (LAS) is a type of Münchausen syndrome characterized by surreptitious abuse of purgatives. Clinical findings are often perplexing and may mimic inflammatory bowel disease or malabsorption syndromes. Patients frequently complain of diarrhea alternating with constipation and may have nausea, vomiting and weight loss. Psychiatric disturbances are common and may include anorexia nervosa. Melanosis coli and cathartic colon, acid-base disturbances (usually metabolic alkalosis), sodium, potassium and water depletion, hyperuricemia, hyperaldosteronism and other electrolyte changes are possible complications. Diagnosis may be extremely difficult and may require special chemical analysis of urine and feces and search of the patient's possessions. Treatment is frustrating because the patient is rarely willing to admit to laxative abuse let alone cooperate in attempting to stop it. Physicians must be aware of the LAS in order to avoid harming the patient with extensive, expensive and often invasive (including laparotomy) procedures.

Acid-Base Imbalance↗
PubMed1978

Dose response to chlorthalidone in patients with mild hypertension. Efficacy of a lower dose.

A multicenter study of chlorthalidone was performed to determine the relative antihypertensive efficacy and side effects of doses lower than those usually recommended for therapy. After a 4-wk placebo control period 100 patients with mild hypertension were randomly assigned doubleblind to 12.5-, 25-, 50-, or 75-mg regimens of chlorthalidone or to placebo for 12 wk. The groups of patients taking 25, 50, and 75 mg had declines in blood pressure which were not significantly different from each other. Serum potassium decreased in the 50- and 75-mg groups but not significantly in the 25-mg group. We conclude that chlorthalidone, 25 mg daily, was at least as effective for hypertension as 50 and 75 mg with less perturbation of potassium. Use of smaller initial diuretic doses may provide equal efficacy with fewer side effects for many patients.

Adult↗
PubMed1976

Antihypertensive effectiveness of oxprenolol administered twice daily.

Oxprenolol, a beta-blocker, is an effective antihypertensive when administered 3 or 4 times daily. We evaluated the antihypertensive effect of oxprenololgiven twice daily (bid). The subjects were 15 ambulatory men whose standing diastolic blood pressure (BP) was at least 100 mm Hg after 3 wk of treatment with hydrochlorothiazide and oxprenolol placebo. Oxprenolol 40 mg twice daily was then substituted for the placebo. On subsequent weekly vists oxprenolol was titrated to 80 and 160 mg bid if the standing diastolic BP was greater than 90 mm Hg. BLood pressures on the last visit on placebo were compared to those on the last visit on oxprenolol. Standing BP declined from 145 +/- 4/108 +/- 1 to 130 +/- 4/98 +/- 4 on a mean dose of 256 mg of oxprenolol (p less than 0.001 syst.; p less than 0.01 diast.). Recumbent BP fell from 146 +/- 4/107 +/- 1 to 138 +/- 5/93 +/- 2 (p less than 0.06 syst.; p less than 0.01 diast.). During the final week, 13 of the 15 patients were admitted to the hospital for 24-hr monitoring of BP. The 24-hr BP readings showed a mean coefficient of variation of 6.6% recumbent and 7.2% standing. we conclude that bid oxprenolol will maintain 24 hr BP control in most patients.

Administration, Oral↗
PubMed1976

Antihypertensive effects of oxprenolol and propranolol.

The antihypertensive effects of the beta blockers oxprenolol and propranolol were compared in a randomized double-blind study of patients with standing diastolic pressures (SDP) exceeding 99 mm Hg when receiving hydrochlorothiazide alone. After 3 wk of hydrochlorthiazide with placebo, the latter was replaced with oxprenolol (n= 12) or propranolol (n = 14), 20 mg three times daily. Beta blocker was increased subsequently to 40 and 80 mg three times daily if SDP exceeded 89 mm Hg. Nine oxprenolol and 7 propranolol subjects were hospitalized for 24-hr monitoring. With oxprenolol, standing pressure declined from 135 +/- 2 (SE)/104 +/- 1 MM Hg to 128 +/- 3/90 +/- 2. SDP declined to under 91 mm Hg in 7 of 12 subjects, and to from 91 to 95 in 3 subjects. With propranolol, findings were 138 +/- 3/106 +/- 2 to 123 +/- 3/89 +/- 3; in 7 of 12 to less than 91 mm Hg and from 91 to 95 in 4 subjects. Decrements in supine and SDP were slightly (4 mm Hg) greater for propranolol than for oxprenolol. Both drugs gave similar 24-hr blood pressure control. We conclude that oxprenolol and propranolol used to supplement hydrochlorothiazide provide comparable reductions in blood pressure and smooth control over a 24-hr period in most patients with hypertension.

Adult↗