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Biomedical subjects

L M Lopez

Publications and source records attributed to L M Lopez.

At least 19 recordsLinked to original sources
PubMed1992

Isradipine--another calcium-channel blocker for the treatment of hypertension and angina.

OBJECTIVE: To review the pharmacology, pharmacokinetic disposition, dose recommendations, adverse effects, drug interactions, and efficacy of isradipine in patients with hypertension or ischemic heart disease. DATA SOURCES: Data from scientific literature were extracted, evaluated, and summarized for presentation. A MEDLINE search was conducted using the following indexing terms: isradipine, calcium-channel blockers, hypertension, and angina pectoris. Experiences from studies evaluating isradipine reported in the form of articles, abstracts, or proceedings involving patients or healthy subjects were considered for inclusion. STUDY SELECTION: Special consideration was given to clinical studies that had been designed in a blind, randomized fashion. Studies that compared the effectiveness and safety of isradipine with another antihypertensive or antianginal agent or placebo were included. DATA EXTRACTION: Data from human studies published in the English language were evaluated. Trials were evaluated according to sample size, design, and adequacy of description of therapeutic response. DATA SYNTHESIS: Isradipine is a new dihydropyridine calcium-channel blocker that appears to exert less negative inotropic activity than nifedipine and to selectively inhibit sinoatrial conduction. Pharmacokinetic parameters are quite variable and considerably more work is needed to better describe the kinetic disposition of isradipine. Antihypertensive efficacy has been demonstrated extensively in a number of short-term trials. Antianginal efficacy also has been observed in a few short-term trials and is comparable to that of isosorbide dinitrate and nifedipine. Extensive experience with isradipine is minimal and no clear-cut advantages over existing compounds have been noted thus far. CONCLUSIONS: The place of isradipine in the therapy of hypertension and myocardial ischemia is unclear and its routine use cannot yet be recommended based solely on clinical grounds.

Angina Pectoris↗
PubMed1992

Comparison of body mass indexes and cutoff points for estimating the prevalence of overweight in Hispanic women.

The anthropometric standards used for estimating the prevalence of overweight among Hispanic groups are generally developed in other populations. Our purpose was to identify appropriate anthropometric indicators and cutoff points for Hispanic women. Data from the Hispanic Health and Nutrition Examination Survey HHANES (1982-1984) included 1,784 Mexican American, 479 Cuban American, and 750 Puerto Rico women aged 25 to 74 years. The body mass indexes examined were weight/standing height1.5, weight/standing height2, weight/sitting height1.5, and weight/sitting height2. Appropriateness was based on correlation of the index with triceps and subscapular skinfold measurements and lack of association with standing or sitting height. The most appropriate indicator was weight/standing height2. To estimate overweight, the 85th percentiles for weight/standing height2 were obtained from the 20- to 29-year-olds in HHANES and the second National Health and Nutrition Examination Survey (NHANES II). For 10-year age intervals, the differences in proportions of women above those cutoff points were compared with a modified t test. The mean estimated prevalences of overweight were significantly higher with the NHANES II standard compared with the HHANES cutoff points (P < .05) for Mexican American women (43% vs 29%) and Puerto Rican women (40% vs 28%). They were slightly lower for the Cuban American women (36% vs 39%). Cutoff points are relative, not absolute, standards that must have biologic meaning. Before our results are used for assessing populations, the cutoff points should be tested for predictive validity with chronic disease rates.

Adult↗
PubMed1991

Around the beta-blockers, one more time.

We review the pharmacology, pharmacokinetics, and relative costs of beta-blockers, as well as indications for and therapeutic controversies surrounding their use. It is hoped that this discussion will assist clinicians in making informed decisions when choosing a drug for a hospital formulary or a particular patient. Beta-blockers are indicated for a variety of noncardiovascular and cardiovascular conditions, including hypertension, ischemic heart disease, arrhythmias, and prophylaxis of myocardial infarction (MI). These agents compete with catecholamines at beta-adrenoreceptors. They have different ancillary properties, including intrinsic sympathomimetic activity (ISA), cardioselectivity, and membrane stabilizing-activity, and vary in their duration of action, route of elimination, and lipophilicity. Beta-blocking agents decrease oxygen demand by exerting a negative inotropic and chronotropic effect. They also reduce blood pressure and possess antiarrhythmic effects. Beta-blockers penetrate the central nervous system (CNS) to different degrees and can cause a wide variety of CNS adverse effects. Nonselective beta-blockers have been noted to slightly reduce renal blood flow. Nadolol is an exception in that either no change, or even a small increase in renal blood flow, is observed upon initiation of therapy. Beta-blockers also act on the pulmonary bed by preventing beta 2-mediated bronchodilation, thereby exacerbating bronchospastic disease in some patients. Beta-adrenergic blocking agents can potentiate both hypoglycemia and hyperglycemia in diabetic patients. Their effects on total peripheral resistance (TPR) are controversial. Initially it appears that beta-blockade increases TPR. After chronic therapy, however, TPR decreases to or below baseline values. These agents appear to be equally efficacious in the treatment of hypertension, arrhythmias, and ischemic heart disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1991

Felodipine: a new dihydropyridine calcium-channel antagonist.

Felodipine, a dihydropyridine calcium-channel antagonist, significantly reduces systolic and diastolic blood pressure (BP) in patients with hypertension and has been associated with beneficial hemodynamic effects in patients with chronic stable angina pectoris or congestive heart failure (CHF). In hypertensive patients, felodipine does not appear to significantly affect glomerular filtration rate, creatinine clearance, glucose tolerance, or plasma lipoprotein concentrations. Studies comparing felodipine with other agents as monotherapy in mild to moderate hypertension have demonstrated felodipine to be at least as efficacious as hydrochlorothiazide (HCTZ) and HCTZ plus amiloride hydrochloride in combination. Comparisons of felodipine with other agents as adjuncts to beta-blocker or diuretic therapy have shown felodipine to be at least as effective as HCTZ, propranolol hydrochloride, prazosin hydrochloride, and nifedipine. Evaluations of patients with chronic stable angina are limited, and additional studies are needed before felodipine can be recommended for the routine management of angina pectoris. Similarly, additional studies are essential to delineate the role of felodipine, if any, in the management of CHF. In the management of hypertension, felodipine 5-40 mg/d significantly reduces systolic and diastolic BP. Although some patients may be controlled throughout the entire dosing interval when felodipine is administered bid, many patients will require more frequent dosing to obtain adequate BP control. Adverse effects associated with felodipine are similar to those of other dihydropyridine calcium-channel antagonists and include peripheral edema, headache, dizziness, flushing, and fatigue. A potentially clinically important drug interaction was observed when felodipine was administered concomitantly with theophylline aminopropanol; significant decreases in theophylline concentrations were noted. In summary, felodipine appears to be safe and effective for the management of hypertension when used alone or in combination with other antihypertensive agents. The efficacy of felodipine in the management of chronic stable angina pectoris and CHF requires further investigation.

Angina Pectoris↗
PubMed1991

Hypertension in the elderly: conventional wisdom revisited.

Elevated systolic and/or diastolic blood pressure in the elderly is a problem the extent of which may be somewhat overstated. In those elderly with definite hypertension, pathophysiology may differ from that of younger counterparts. The contribution of elevated plasma renin activity to hypertension and to the choice of therapy also appears to be exaggerated. The risks of ignoring hypertension in the elderly are similar to those in younger patients, and therefore excessively elevated blood pressure should no longer be considered a normal consequence of aging. Notably, elevated systolic pressure is a better predictor of future adverse occurrences than is elevated diastolic pressure. Unfortunately, there is no well defined therapeutic regimen to manage isolated systolic hypertension. Conservative reduction of elevated systolic and diastolic pressures may nevertheless be accomplished safely and effectively. Individualization of therapy is recommended based primarily on concomitant disease(s). Thus no single agent or combination of agents is preferable in all elderly hypertensive patients. Aggressive use of non-pharmacologic therapy preferably precedes judicious of antihypertensive medication. Aggressive blood pressure reduction with potent drugs is not recommended.

Adrenergic beta-Antagonists↗
PubMed1990

Simultaneous determination of propranolol and 4-hydroxypropranolol enantiomers after chiral derivatization using reversed-phase high-performance liquid chromatography.

A reversed-phase high-performance liquid chromatographic method is described, which allows the simultaneous quantification of propranolol and 4-hydroxypropranolol enantiomers in human plasma. After extraction from plasma (pH 10.5) using ethyl acetate, the enantiomers are derivatized with R-(+)-phenylethylisocyanate as chiral derivatization reagent and triethylamine as basic catalyst in chloroform. Ascorbic acid is used to prevent 4-hydroxypropranolol from oxidation during the extraction. Chromatographic separation on ODS columns and fluorescence detection (228 nm/greater than 340 nm) allows sensitive quantitation of all derivatives. Incubation of the plasma samples with beta-glucuronidase/arylsulfatase and the use of the specific beta-glucuronidase inhibitor saccharo-1,4-lactone allows the quantitation of both the sulfate and glucuronide conjugates of the enantiomers. The method was applied to human plasma samples from a subject after administration of 60 mg racemic propranolol three times daily.

Animals↗
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↗