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Biomedical subjects

L M Lopez

Publications and source records attributed to L M Lopez.

At least 55 records · Page 3Linked to original sources
PubMed1990

Nitrendipine: a new dihydropyridine calcium-channel antagonist for the treatment of hypertension.

Nitrendipine, an investigational dihydropyridine calcium-channel antagonist for the treatment of hypertension, is reviewed. Clinical trials report efficacy equal to that of hydralazine, diuretics, beta-blockers, and other calcium-channel blockers such as nifedipine, verapamil, and isradipine. Nitrendipine has a favorable pharmacokinetic profile in that it is well absorbed and has a half-life long enough to allow once-daily administration in some patients. However, considerable variation observed with some pharmacokinetic parameters has consequently delayed marketing approval by the Food and Drug Administration. Adverse effects are generally mild and transient, and result from nitrendipine's vasodilatory properties. Nitrendipine may increase digoxin plasma concentrations in some patients, but this may not be clinically significant. Other studies are required to ascertain which drugs interact with nitrendipine. In summary, nitrendipine is safe and effective for treatment of hypertension, and because of its longer duration of action as well as lack of metabolic side effects, may provide an alternative to the present antihypertensive armamentarium.

Animals↗
PubMed1988

Lisinopril versus lisinopril plus hydrochlorothiazide in essential hypertension.

The efficacy of a new angiotensin converting enzyme inhibitor, lisinopril, used alone (group A) was compared with lisinopril plus hydrochlorothiazide (group B) in 26 patients with essential hypertension. Therapy with both regimens was equally effective in lowering blood pressure compared to placebo. Mean antihypertensive dose of lisinopril was lower when given in combination with hydrochlorothiazide than when given alone (48 +/- 6 vs 68 +/- 12 mg daily). Plasma renin activity increased in both groups of patients, but more in group B (p less than 0.05). Plasma aldosterone concentrations and serum uric acid levels were also higher in the group receiving lisinopril plus hydrochlorothiazide (p less than 0.05). Serum potassium concentrations were unaffected in either group. The incidence of side effects was similar in groups A and B (44% and 38%, respectively). This study suggests that lisinopril alone or in combination with hydrochlorothiazide effectively lowers blood pressure in patients with essential hypertension without any major side effects.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1988

Dietary supplementation with omega-3 polyunsaturated fatty acids in patients with stable coronary heart disease. Effects on indices of platelet and neutrophil function and exercise performance.

It has been suggested that omega-3 polyunsaturated fatty acids (PUFAs) may alter the course of coronary artery disease by influencing platelet and neutrophil function, arachidonic acid metabolism, and circulating lipid concentrations. To examine this hypothesis, placebo or omega-3 PUFAs as Max-EPA (equivalent to 3.2 g of eicosapentaenoic acid and 2.2 g of docosahexaenoic acid daily) was administered to eight patients with stable coronary artery disease and positive exercise stress test results in a randomized, double-blind, crossover fashion over a 12-week period. With Max-EPA administration, platelet aggregation threshold to epinephrine was increased in only two patients, but neutrophil aggregation and chemotaxic functions decreased consistently (both p less than or equal to 0.01 compared with preceding placebo phase) in all eight. Serum and platelet-rich plasma thromboxane B2 concentrations decreased 40 percent and 28 percent, respectively (both p less than or equal to 0.05). Neutrophil leukotriene B4 formation decreased 23 percent (p less than or equal to 0.01) and synthesis of leukotriene B5 became apparent in all subjects. Serum triglyceride concentrations fell 52 percent (p less than or equal to 0.05) without significant change in total cholesterol, high-density lipoprotein-cholesterol, or low-density lipoprotein-cholesterol concentrations. Systolic blood pressure and the double product (heart rate X systolic blood pressure) were lower (p less than or equal to 0.05) at the end of the Max-EPA phase than in the preceding placebo phase. Heart rate, systolic blood pressure, and the double product were also lower (p less than or equal to 0.05) at three as well as at six minutes of an exercise stress test, indicating a significant reduction in myocardial oxygen demand. Despite these alterations in platelet and neutrophil function, arachidonic acid metabolism, serum triglyceride concentrations, and myocardial oxygen demand, there were no significant changes in subjective parameters of coronary artery disease during the Max-EPA phase (angina frequency 3.7 versus 2.8 episodes per week, nitroglycerin consumption 3.0 versus 1.9 tablets per week, both p = NS). Similarly, exercise times to ST-segment depression (6.5 versus 4.1 minutes) and to onset of angina (5.4 versus 5.0 minutes) were not altered by administration of Max-EPA. Thus, short-term dietary supplementation with omega-3 PUFAs to patients with stable coronary artery disease does not appear to alter subjective or objective parameters of myocardial ischemia.

Aged↗
PubMed1988

Lisinopril: a new angiotensin-converting enzyme inhibitor.

Lisinopril is a new, nonsulfhydryl angiotensin-converting enzyme inhibitor approved for the treatment of hypertension. After oral administration, 25-29 percent of the dose is absorbed intact; biotransformation is not required for pharmacological activity. Onset of action occurs one to two hours after administration, with effects still present 24 hours later. The major route of elimination is through renal excretion and an elimination half-life of 12.6 hours has been reported in normotensive individuals. In patients with impaired renal function (creatinine clearance less than or equal to 30 ml/min) a longer half-life and accumulation have been observed. Lisinopril 20-80 mg/d has been shown to be as effective as hydrochlorothiazide, nifedipine, and beta-blocking agents in the treatment of essential hypertension. Its efficacy in renovascular hypertension has also been demonstrated. In congestive heart failure (CHF) doses of 2.5-20 mg/d appear to provide hemodynamic effects comparable to those of captopril. Dizziness and cough have been the most frequently reported side effects; rash and proteinuria have also been reported in a small number of patients. Interactions with diuretics, potassium supplements, and possibly with nonsteroidal antiinflammatory agents may occur. Lisinopril appears to be similar in efficacy to other antihypertensive agents in the treatment of essential hypertension and to captopril in the treatment of CHF. Whether lisinopril is safer or more effective than captopril or enalapril in the treatment of hypertension or CHF requires further investigation. Prolonged duration of action of lisinopril allows once daily dosing, unlike captopril for which dosing is required every 8-12 hours or enalapril which may necessitate twice daily dosing.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1988

Comparative evaluation of enalapril and hydrochlorothiazide in elderly patients with mild to moderate hypertension.

Initial treatment of elderly hypertensive patients with an angiotensin-converting enzyme inhibitor is currently discouraged due to such patients' typical low-renin profile. To validate this principle, we studied 38 elderly males (aged greater than or equal to 65 years) with mild to moderate hypertension, comparing hemodynamic responses to and subjective impressions of enalapril or hydrochlorothiazide (HCTZ). After gradual withdrawal of existing antihypertensive therapy and a four-week, single-blind placebo period, each patient was randomized in a double-blind fashion to receive either enalapril 10-20 mg/d or HCTZ 12.5-25 mg/d for two to four weeks. Combination therapy with both agents was employed if either alone failed to reduce seated diastolic BP to less than or equal to 90 mm Hg. Equivalent proportions of patients receiving enalapril or HCTZ (8 of 19 and 10 of 19, respectively; p = ns) responded with significant reductions in systolic and diastolic BP in seated and standing positions. Combination therapy was most effective in patients receiving HCTZ prior to enalapril. In patients receiving enalapril before HCTZ, BP changes were minimal. No adverse effects were observed in the enalapril group but occurred in an equivalent fraction of patients in the other groups (4 of 10 HCTZ alone, 6 of 20 enalapril + HCTZ; p = ns). We conclude that enalapril may be considered a reasonable monotherapeutic antihypertensive agent in some elderly patients. Combination with HCTZ is beneficial in patients who fail to respond adequately to HCTZ alone.

Aged↗
PubMed1988

Management of congestive heart failure in the elderly.

A universally accepted description of appropriate therapy for treatment of congestive heart failure (CHF) has yet to be agreed upon, especially in the elderly. Numerous studies have provided data that question use of a digitalis glycoside as the agent of choice in treatment of chronic CHF. Several clinicians have suggested that diuretics, particularly thiazide diuretics, be used as initial agents in the treatment of this condition. Evidence now demonstrates that drug therapy with enalapril or the combination of hydralazine and isosorbide dinitrate reduces the mortality related to chronic CHF. Additional studies are required to clarify respective roles of diuretics, digitalis glycosides, and vasodilators in the management of chronic CHF.

Aged↗
PubMed1987

Similar efficacy of nitrendipine in young and elderly hypertensive patients.

Calcium channel blockers have been postulated to be more effective as monotherapeutic antihypertensive agents in the elderly than in younger patients. To determine if a new dihydropyridine derivative, nitrendipine, is more effective in the elderly (older than 60 years) than in younger hypertensive subjects (younger than 60 years), nitrendipine was administered in a multicentered study to 21 elderly and 33 younger subjects with essential hypertension. After gradual discontinuation of previous antihypertensive therapy and 2 weeks of placebo, the daily dose of nitrendipine (10 to 40 mg) was titrated over 3 weeks to achieve a 10 mm Hg decrease in supine diastolic blood pressure (BP) for patients entering with 90 to 99 mm Hg. For patients entering with at least 100 mm Hg, the dose was titrated to diastolic BP no greater than 90 mm Hg. Titrated dose of nitrendipine was maintained for 4 additional weeks. Propranolol was added for "symptomatic" tachycardia. Nitrendipine reduced BP in 90% of patients completing all phases of the study (n = 49). The proportion of responders was 47% among the elderly and 44% among young subjects. Change in heart rate was similar in both groups (-0.1 +/- 9.9 and +2.9 +/- 8.8 beats/min, mean +/- standard deviation). Two elderly and 1 younger subject required addition of propranolol (difference not significant). There was no correlation between the age of patients and changes in supine systolic and diastolic BP or heart rate (r = 0.21, -0.15 and -0.21, respectively). Adverse effects occurred with equal frequency in older and younger subjects (19 of 21 vs 23 of 33 patients, difference not significant).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Serum lidocaine concentrations following application to the oropharynx: effects of cimetidine.

Solutions of lidocaine hydrochloride are widely used for anesthesia of the oropharynx and respiratory tract prior to endoscopic procedures. It is commonly believed that this route of administration is not associated with clinically significant systemic absorption of the drug, and large doses of topical lidocaine are routinely used in this setting. Serious adverse effects, including seizures, occasionally occur. The extent of absorption of lidocaine from the oropharynx was studied in eight healthy volunteers. Wide variation in serum lidocaine concentrations was observed. A 14-fold range of peak lidocaine concentrations occurred following identical, accurately metered doses of a lidocaine aerosol spray preparation. The effects of cimetidine on lidocaine pharmacokinetics were also studied. Therapeutic doses of oral cimetidine significantly increased the area under the lidocaine time-concentration curve (p = 0.019), but no effect on the terminal-phase elimination rate constant was observed. Serum concentrations of alpha 1-acid glycoprotein, a major binding protein of lidocaine, were significantly elevated following cimetidine (p = 0.030). Maximum lidocaine concentration, time to reach maximum concentration, and mean residence time of lidocaine were unchanged following cimetidine. These observations suggest an effect of cimetidine on the volume of distribution of lidocaine. Because of the wide variability in lidocaine pharmacokinetics and the potentially serious nature of adverse reactions, caution is advised in the use of topical lidocaine solutions in "standard" doses.

Administration, Topical↗
PubMed1987

Effect of new Vacutainer blood collection tubes on plasma lidocaine concentrations.

This study was designed to establish whether plasma lidocaine concentrations changed subsequent to contact with a new formulation of rubber-stopper Vacutainer collection tubes. Plasma lidocaine concentrations from blood samples exposed to rubber stoppers for one hour were compared with concentrations from blood samples which were not exposed to rubber stoppers. Plasma lidocaine concentrations remained essentially unchanged following one-hour exposure to Vacutainer rubber stoppers. The new formulation of "red-top" Vacutainer may be used reliably in lidocaine therapeutic drug monitoring.

Blood Specimen Collection↗
PubMed1987

Food stamps and the iron status of the U.S. elderly poor.

With the use of data from NHANES I and II, the iron status of poor elderly persons was examined by comparing it with that of nonpoor elderly persons. Within the poor group, the iron status of Food Stamp Program participants was compared with that of nonparticipants. The poor were those below the poverty line; the nonpoor were those with incomes at least twice the poverty line. The indicators of iron status were: hemoglobin, hematocrit, free erythrocyte protoporphyrin, transferrin saturation, total iron-binding capacity, serum iron, and iron intake. Iron status was examined by analyses of variance. The effects associated with sex, race, age, geographic region, and other potentially confounding factors were included in the model. In both surveys, there were interactions with race. That is, the poor whites had lower transferrin saturation and iron intake means than the nonpoor whites, while the Food Stamp Program participants were no different from the nonparticipants in transferrin saturation. Within the nonwhites, the poor had a lower hemoglobin mean than the nonpoor, and the program participants had a lower hemoglobin mean than the nonparticipants. Therefore, the Food Stamp Program was not consistently associated with better iron nutrition of the elderly poor in NHANES I and II.

Aged↗
PubMed1987

Food stamps and the energy status of the U.S. elderly poor.

The energy status of poor elderly individuals in relation to the nonpoor elderly was examined using data from NHANES I and II. Within the poor population, the status of Food Stamp Program participants was compared with that of nonparticipants. The indicators of energy status used were weight (adjusted for height), triceps skinfold, subscapular skinfold, and energy intake. Energy status was examined by analyses of variance; the effects associated with sex, race, age, geographic region, and other potentially confounding variables were included in the model. In both surveys, there were interactions of income and food stamp use with sex. That is, poor women had greater means for weight and triceps skinfold than the nonpoor. Among the poor women, the Food Stamp Program participants weighed more than the nonparticipants, and their triceps skinfold mean was greater in NHANES II than in NHANES I. The poor men had a lower mean for triceps skinfold than the nonpoor, but there was no difference between the program participants and nonparticipants. Hence, for the poor elderly in NHANES I and II, food stamp use was not consistently associated with differences in energy status, as indicated by weight, skinfold, and energy intake.

Aged↗
PubMed1987

Rebound hypertension following abrupt cessation of clonidine and metoprolol. Treatment with labetalol.

Abrupt withdrawal of adrenergic blockers in a hypertensive subject may result in acute hypertensive crisis. This crisis results from marked increase in adrenergic discharge and upregulation of adrenoceptors. In a patient with hypertensive crisis following abrupt cessation of clonidine hydrochloride and metoprolol tartrate, intravenous administration of labetalol hydrochloride rapidly reduced blood pressure and heart rate to precrisis levels. The patient was subsequently maintained in a normotensive state by continued oral use of labetalol. This case study demonstrates that alpha- and beta-blocking activities of labetalol may be particularly beneficial in a hyperadrenergic state following abrupt withdrawal of adrenergic blockers.

Aged↗
PubMed1986

Calcium-blocker withdrawal phenomenon: increase in affinity of alpha 2 adrenoceptors for agonist as a potential mechanism.

Precipitation of myocardial ischemia after withdrawal of calcium channel blocking drugs has been observed in some patients, but the mechanism of this phenomenon is not known. Among 15 patients with coronary artery disease who had been treated with nisoldipine, onset of severe unstable angina was observed in 2 and evolution of acute myocardial infarction in 1 patient after abrupt withdrawal of nisoldipine therapy. To determine a mechanism of myocardial ischemia after cessation of nisoldipine therapy, the status of alpha 2 adrenoceptors and platelet sensitivity to epinephrine was examined in 5 patients. After 6 weeks of therapy, there were no changes in the number of alpha 2 adrenoceptors (199 +/- 45 vs 188 +/- 35 fmol/mg protein, mean +/- standard error of the mean) or affinity for antagonist (dissociation constant 5.78 +/- 0.99 vs 4.70 +/- 0.87 nM), but there was a significant (p less than 0.01) increase in the affinity of alpha 2 adrenoceptors for agonist epinephrine. In vitro platelet sensitivity to epinephrine, but not ADP, also increased markedly. It is postulated that an increase in alpha 2-adrenoceptor affinity for agonist may relate to platelet hyperactivity, which may result in severe myocardial ischemia upon withdrawal of calcium blocking drugs in some patients.

Adult↗