PubMed Health⌕ Search

Biomedical subjects

D R Geraets

Publications and source records attributed to D R Geraets.

12 recordsLinked to original sources
PubMed1994

Digoxin disposition in elderly humans with hypochlorhydria.

Digoxin (D3) metabolism is partially mediated by the gastrointestinal tract via acid hydrolysis of digitoxose sugar moieties and bacterial reduction of the lactone. The hypothesis that hypochlorhydria influences digoxin disposition was tested in six normochlorhydric (NC) and four hypochlorhydric (HC) subjects. D3 tablets were administered daily for 19 to 28 days, and quantitative urine and fecal samples were collected over the last 3 days (steady state). Samples were analyzed for D3 and its extractable metabolites by fluorescence-derivatization HPLC. Excretion of D3 in urine increased from 37% of the dose in NC to 46% in HC, whereas excretion of D3 in feces decreased from 29 to 14%. These changes were statistically significant (P < .05) and consistent with decreased hydrolysis of D3 by stomach acid and increased intestinal metabolism in HC. In each subject, D3 was added to anaerobic cultures of both feces and jejunal fluid. Digoxin was reduced in all but two of the fecal incubates, and was not reduced in any jejunal fluid incubates. Because dihydrodigoxin (DHD3) was found in only two hypochlorhydric subjects, in vitro measures of bacterial reduction of D3 were not predictive of in vivo excretion of reduced metabolites. Sugar-hydrolyzed, reduced metabolites were not found in any subjects. It is concluded that D3 disposition is altered by hypochlorhydria, and that an understanding of the metabolic mechanisms requires further study.

Achlorhydria↗
PubMed1993

Atrial fibrillation and atrial flutter.

The epidemiology, pathophysiology, diagnosis, evaluation, and treatment of atrial fibrillation (AF) and atrial flutter (AFl) are reviewed, and recent developments and controversies in the approach to these arrhythmias are addressed. AF and AFl are the arrhythmias most frequently encountered in clinical practice. Although occasionally unaware of their arrhythmia, patients usually complain of palpitations, weakness, dyspnea, and decreased exercise tolerance. The initial goal of therapy is control of the ventricular rate. Rate control is accomplished with atrioventricular node-blocking agents such as digoxin, calcium-channel blockers, or beta-adrenergic blockers. Along with a rapid, irregular ventricular response, other detrimental outcomes of AF and AFl include compromised hemodynamics and increased vulnerability to thromboembolism. After the cause of the patient's arrhythmia has been evaluated, pharmacologic treatment is directed at converting the rhythm to normal sinus rhythm and maintaining it. Antiarrhythmic drugs have proved effective in about 50% of cases but may be associated with increased mortality. More effective and safer forms of drug therapy for AF and AFl are needed. Nonpharmacologic alternatives to antiarrhythmic medications for refractory AF and AFl include radio-frequency catheter ablation of the bundle of His with pacemaker placement and surgery. Patients who remain in AF despite therapy should receive long-term warfarin treatment. Drugs may be used to control the ventricular response in patients with AF and AFl, terminate and prevent the arrhythmias, and prevent thromboembolism. Nonpharmacologic treatments are reserved for patients whose arrhythmias are poorly controlled by drugs.

Adrenergic beta-Antagonists↗
PubMed1992

Toxicity potential of oral lidocaine in a patient receiving mexiletine.

OBJECTIVE: To report a case of toxicity from orally administered lidocaine in a patient with cardiomyopathy receiving concurrent mexiletine therapy. DATA SOURCES: Case reports, review articles, and studies identified by search of the MEDLINE database and Current Contents. STUDY SELECTION: All reports of toxicity from orally administered lidocaine were reviewed. DATA SYNTHESIS: Lidocaine, a local anesthetic, is widely used to treat cardiac arrhythmias. Toxicity with the parenteral form occurs frequently. In contrast, there are few reports of toxicity with oral lidocaine, most of them occurring in children receiving large doses relative to body weight. We report a case of intoxication in an adult with severe cardiomyopathy and concurrent mexiletine therapy who received only two doses of oral lidocaine. CONCLUSIONS: Although it is rarely reported in adults, clinicians must be alert to the possibility of toxicity from orally administered lidocaine. This is most likely to occur in patients with conditions known to reduce lidocaine clearance, when higher-than-usual doses are administered, or when concurrent therapy with oral lidocaine analogs may be present.

Administration, Oral↗
PubMed1991

Inhibitory effects of procainamide on sympathetic nerve activity in humans.

In experimental animals, procainamide causes hypotension and reductions in efferent vasoconstrictor sympathetic outflow that may result from ganglionic blockade or central nervous system sympathetic inhibition. To test the hypothesis that procainamide decreases sympathetic nerve activity (SNA) in humans, we recorded postganglionic SNA in seven normal subjects in the baseline state and during infusions of procainamide HCl at 50 mg/min (loading) and 8 mg/min (maintenance). At the end of the loading infusion, mean arterial pressure (MAP) had decreased from 88.5 +/- 2.4 (mean +/- SEM) to 81.5 +/- 3.2 mm Hg (p less than 0.05), central venous pressure from 6.7 +/- 0.7 to 5.4 +/- 0.9 mm Hg (p less than 0.05), forearm vascular resistance (FVR) from 28 +/- 4.8 to 22.3 +/- 5.1 resistance units (p less than 0.05), and SNA from 259 +/- 47 to 94 +/- 26 units/min (p less than 0.05). These changes persisted during the maintenance infusion. Increased levels of SNA, FVR, and MAP provoked by the cold pressor test were reduced significantly by intravenous procainamide. In eight other subjects, intravenous procainamide HCl (15 mg/kg at 50 mg/min) caused dose-dependent inhibition of SNA that reversed as blood concentrations fell during drug washout. To determine if procainamide causes direct vasodilation, in nine subjects, graded infusions were delivered into the brachial artery at doses that produced no systemic effect. Ipsilateral FVR tended to increase during local intra-arterial infusion of procainamide. These data show that intravenous procainamide causes hypotension, vasodilation, and sympathetic withdrawal. Vasodilation does not result from a direct vasorelaxant effect of the drug.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Apparent failure of edetic acid chelation therapy for the treatment of coronary atherosclerosis.

Patients diagnosed with incurable or fatal diseases may seek alternatives to standard medical therapy and spend significant amounts of money for these therapies. One alternative medical therapy, chelation therapy with edetic acid (EDTA), has gained considerable popularity for the alleged treatment of atherosclerotic vascular disease; however, its efficacy for this indication remains unproven and its use is controversial. We present a case in which chelation therapy was unsuccessful in treating coronary atherosclerosis and review reports that substantiate a lack of efficacy using chelation therapy in the treatment of coronary atherosclerosis. Treatment of atherosclerotic-related diseases using chelation therapy should be discouraged by health professionals. Patients should be counseled regarding the risk of improper diagnosis and treatment of their disease.

Aged↗
PubMed1990

Reports of erythematous macular skin eruptions associated with diltiazem therapy.

Diltiazem is a commonly prescribed calcium-channel antagonist for hypertension and ischemic heart disease. The incidence of rash associated with diltiazem therapy is reported to be 1.3 percent. We describe two patients who developed erythematous, macular skin eruptions, approximately two weeks following institution of diltiazem. The skin eruptions resolved after symptomatic treatment and the patients received further therapy with another calcium-channel antagonist. Diltiazem-associated skin eruptions are a rare adverse effect; however, the incidence of rash may occur more frequently than reported in postmarketing surveillance studies.

Aged↗
PubMedDate not supplied

Thrombolytic-associated cholesterol emboli syndrome: case report and literature review.

Thrombolytics can cause cholesterol embolization syndrome (CES). This adverse effect has received less attention than other risks of thrombolytic therapy, such as systemic bleeding and hemorrhage, with only sporadic reports of CES in the literature. Risk factors have not been consistently identified and emphasized; therefore, occurrence of CES after thrombolysis remains difficult to predict, it results in substantial morbidity and mortality, and it lacks effective pharmacologic treatment. Heightened awareness of the disorder can aid in its correct identification and reporting.

Central Nervous System Diseases↗
PubMedDate not supplied

Disposition of tablet and capsule formulations of digoxin in the elderly.

STUDY OBJECTIVE: To compare digoxin tablets and liquid-filled capsules with respect to excretion of the drug and its metabolites in urine and feces at steady state. DESIGN: A randomized, crossover trial, each period lasting 3 weeks, with no washout period. SETTING: A university hospital. PATIENTS: Six patients, five of whom were elderly, with histories of gastrointestinal disorders, such as hypochlorhydria, intestinal bacterial overgrowth, and inflammatory bowel disease. INTERVENTIONS: The patients received digoxin once/day in either tablet or capsule form for 3 weeks, and then were switched to the other formulation. Total urinary and fecal excretion from the last 3 days of each regimen were analyzed for the drug and metabolites. MEASUREMENTS AND MAIN RESULTS: No statistically significant differences were found between tablets and capsules in recovery of digoxin or its metabolites in urine or feces (p = 0.05). One subject had a 4-fold increase in urinary drug excretion and 50% decrease in fecal excretion after taking the capsules compared with tablets. Intersubject variability in extent and type of metabolite excretion was greater than intrasubject variability. CONCLUSIONS: Fecal analyses may be an accurate way to classify patients as formers of digoxin reduction products.

Aged↗