Anticoagulation and elective surgery.
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Anticoagulants↗
Biomedical subjects
S M Mohiuddin
Publications and source records attributed to S M Mohiuddin.
Cost-minimization analysis of intravenous adenosine and dipyridamole in thallous chloride TI 201 SPECT myocardial perfusion imaging.
OBJECTIVE: To conduct a cost-minimization analysis of intravenous adenosine and intravenous dipyridamole in thallous chloride TI 201 single-photon emission computed tomography (SPECT) myocardial perfusion imaging. DESIGN: A retrospective, open-label, cost-minimization analysis. SETTING: University hospital, outpatient nuclear medicine department. PATIENTS: Eighty-three patients undergoing dipyridamole TI 201 SPECT and 166 patients undergoing adenosine TI 201 SPECT. MAIN OUTCOME MEASURES: A cost-minimization analysis was conducted using a direct cost accounting approach estimating institutional costs. For the purpose of this study, sensitivity and specificity between adenosine SPECT and dipyridamole SPECT were assumed to be identical. Key costs evaluated included acquisition, administration, monitoring, treatment of adverse effects, follow-up care, and repeat tests. RESULTS: Adenosine increased heart rate and lowered blood pressure to a significantly greater extent than dipyridamole. The frequency of adverse reactions was not significantly different (p = 0.103) between adenosine (1.64 +/- 1.32 per patient) and dipyridamole (1.36 +/- 1.23 per patient). The frequency of prolonged and late-onset adverse effects was significantly greater for dipyridamole than for adenosine (p < 0.001). The frequency of adverse events requiring medical intervention was statistically greater for dipyridamole (24%) compared with adenosine (5%) (p < 0.00001). Total cost was significantly less for adenosine ($378.50 +/- $128.20 per patient) compared with dipyridamole ($485.60 +/- $230.40). Although adenosine had a significantly greater acquisition cost than dipyridamole (p < 0.0001), administration, monitoring, and adverse reaction costs were significantly less for adenosine than for dipyridamole. CONCLUSIONS: The cost of using dipyridamole is significantly greater than the cost of using adenosine despite adenosine's high acquisition cost. Adenosine is less expensive to use because of lower administration costs, monitoring costs, and adverse effect costs. Adenosine should be the agent of choice for pharmacologic vasodilation in the setting of myocardial perfusion imaging.
Adenosine↗
Further elucidation of pharmacokinetic interaction between diltiazem and warfarin.
Diltiazem and warfarin are both highly protein-bound providing the opportunity for a protein-binding displacement interaction to occur. Additionally, diltiazem has demonstrated the ability to inhibit the metabolic clearance of hepatically cleared drugs (e.g. warfarin). We evaluated these pharmacokinetic mechanisms for a potential interaction. A single warfarin 25 mg oral dose was given with and without oral diltiazem 30 mg 3 times daily to 20 healthy male volunteers in a randomized crossover design with a washout period of at least 6 days. Serial blood samples for INRs and free and total warfarin concentrations were obtained over 144 hours after each warfarin dose. Free fraction was extracted by equilibrium dialysis and free and total warfarin concentrations were analyzed by HPLC. Anticoagulation was assessed using AUC0-6,INR (days). Diltiazem was found not to potentiate anticoagulation by warfarin. Furthermore, warfarin protein binding displacement did not occur. Diltiazem inhibited both free and total warfarin clearance, though not statistically significant. Although slightly inhibiting metabolism of warfarin, based on warfarin clearance, diltiazem did not increase warfarin's anticoagulant effect making it an acceptable addition to therapy if required.
Adult↗
Stress testing with closed-loop arbutamine as an alternative to exercise. The International Arbutamine Study Group.
OBJECTIVES: This study compared exercise and pharmacologic stress testing using arbutamine delivered by a closed-loop device for the detection of coronary artery disease. BACKGROUND: Arbutamine, an agent designed to simulate exercise, has been developed in conjunction with a closed-loop delivery device that modulates the rate of administration on the basis of physiologic feedback. METHODS: Two hundred ten patients (180 men, 30 women) with symptoms and angiographic evidence of coronary artery disease were studied. Ischemia was categorized in three ways: 1) the presence of angina; 2) the occurrence of > or = 0.1-mV horizontal or downsloping ST segment depression or elevation at 60 ms after the J point; or 3) the presence of either condition 1 or 2. RESULTS: In the 210 patients, the mean increase in heart rate and systolic blood pressure evoked by arbutamine and exercise was 51 and 53 beats/min (p = NS) and 36 and 44 mm Hg (p < 0.0001), respectively. Arbutamine detected ischemia more often than exercise with each of the three ischemic end points. Sensitivity for detecting ischemia by either angina or ST segment change was 84% (95% confidence interval ¿ change was 84% (95% confidence interval [CI] 79% to 89%) for arbutamine and 75% (95% CI 69% to 81%) for exercise testing (p = 0.014). For angina alone, sensitivity was 73% (95% CI 67% to 79%) for arbutamine and 64% (95% CI 57% to 71%) for exercise (p = 0.026). For ST segment change alone, sensitivity was 47% (95% CI 40% to 54%) for arbutamine and 44% (95% CI 37% to 51%) for exercise (p = 0.426). Cardiac events occurred in five patients (1.8%) within 24 h of the arbutamine test. CONCLUSIONS: In detecting documented coronary artery disease, the sensitivity of arbutamine testing was equal to that of exercise for the electrocardiographic end point of ST segment change alone. Arbutamine testing was significantly superior to exercise testing for either ST change or angina or for angina alone.
Aged↗
Comparison of fixed-dose transdermal nicotine, tapered-dose transdermal nicotine, and buspirone in smoking cessation.
The authors compared the outcome of 208 smokers treated with fixed-dose transdermal nicotine (n = 69), tapered-dose transdermal nicotine (n = 71), or buspirone (n = 68). At baseline, there were no significant differences among the three treatment groups with regard to age, gender, educational level, duration of smoking, number of cigarettes smoked per day, concomitant disease states or drug use, or Fagerstrom score. All smokers participated in a behavior modification program. Fixed-dose transdermal nicotine was given at a dose of 21 or 22 mg/day for 6 weeks. Tapered-dose transdermal nicotine was given at a dose of 21 or 22 mg/day for 4 weeks, 14 mg/day for 4 weeks and 7 mg/day for 4 weeks. Both transdermal nicotine regimens were initiated on the evening before the attempted quit date. Buspirone was started 21 days before the quit attempt and continued for 7 days after the quit attempt. Buspirone was initiated at 5 mg TID for 7 days and then 10 mg TID for 21 days. Smoking cessation was assessed by patient diaries and random plasma thiocyanate determinations. Dropouts for any reason were considered treatment failures. Quit rates were as shown in the Table I. Discontinuation of treatment for perceived side effects and dropouts for all reasons were not significantly different among the treatment groups. The authors conclude that fixed-dose transdermal nicotine, tapered-dose transdermal nicotine, and buspirone are associated with similar efficacy and safety when combined with behavior modification in smoking cessation.
Administration, Cutaneous↗
Inversion of the left atrial appendage: clinical and echocardiographic correlates.
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Adult↗
Safety of esmolol in patients with acute myocardial infarction treated with thrombolytic therapy who had relative contraindications to beta-blocker therapy.
OBJECTIVE: This study was conducted to evaluate the safety of esmolol in 114 patients treated with thrombolytic therapy for acute myocardial infarction who also had relative contraindications to beta-blockade, and the predictive value of patient tolerance to esmolol and subsequent patient tolerance of oral beta-blocker therapy. PATIENTS: One hundred and fourteen patients with myocardial infarction documented by enzyme concentrations and electrocardiographic changes who also had relative contraindications to beta-blockade. METHODS: Esmolol was initiated during acute myocardial infarction for myocardial ischemia (n = 88), hypertension (n = 13), or supraventricular tachycardia (n = 13). Relative contraindications to beta-blocker therapy included either active signs/symptoms of left ventricular dysfunction or a history of congestive heart failure (n = 40), a history of chronic obstructive pulmonary disease or asthma (n = 31), bradycardia (HR < 60 beats/min; n = 18), peripheral vascular disease (n = 15), or hypotension (systolic BP < 100 mm Hg; n = 14). RESULTS: During initial esmolol dose titration, 69 patients tolerated 300 micrograms/kg/min, 12 patients tolerated 200 micrograms/kg/min, 17 patients tolerated 100 micrograms/kg/min, and 16 patients tolerated 50 micrograms/kg/min. Twenty-eight patients (25 percent) developed dose-limiting adverse effects during esmolol maintenance infusions. Sixteen patients required esmolol dose reduction and 12 required esmolol discontinuation. Adverse effects reversed within 30-45 minutes following dose reduction or discontinuation. The 86 patients who tolerated esmolol infusions without dose reduction or drug discontinuation were subsequently treated with oral beta-blockers. Eleven of these patients (13 percent) developed adverse effects requiring oral beta-blocker discontinuation. Nine of these patients had tolerated only 50 micrograms/kg/min of esmolol, and the other 2 patients had tolerated only 100 micrograms/kg/min. CONCLUSIONS: Esmolol can be used safely in most patients treated with thrombolytic therapy for acute myocardial infarction who have relative contraindications to beta-blockers. Tolerance to higher maintenance doses of esmolol is a good predictor of subsequent outcome with oral beta-blocker therapy.
Adrenergic beta-Antagonists↗
Nonsteroidal antiinflammatory drug use in patients receiving warfarin: emphasis on nabumetone.
Phenylbutazone has been clearly demonstrated to interact pharmacokinetically and clinically with warfarin, although several other nonsteroidal antiinflammatory drugs (NSAIDs) also have the potential to interact with warfarin to cause alterations in prothrombin time. Aspirin is known to inhibit platelet aggregation irreversibly, whereas nonaspirin NSAIDs are thought to inhibit platelet aggregation reversibly. In contrast, nabumetone was not shown to cause significant inhibition of platelet aggregation, which may be related to the fact that nabumetone preferentially inhibits the prostaglandin synthase-2 isozyme instead of the prostaglandin synthase-1 isozyme. Furthermore, in studies in patients and normal volunteers stabilized on warfarin, nabumetone did not cause alterations in the prothrombin time or international normalized ratio. Based on data evaluating the concomitant use of nabumetone and warfarin, the relative lack of platelet inhibition, and the relatively lower risk of nabumetone-induced gastrointestinal mucosal damage as assessed by radiolabeled chromium-51 fecal blood loss studies and endoscopic evaluations, nabumetone may be preferred if concomitant therapy with warfarin is indicated.
Anti-Inflammatory Agents, Non-Steroidal↗
Loss of efficacy during long-term cifenline therapy: development of antiarrhythmic resistance?
OBJECTIVE: To describe the possible development of antiarrhythmic resistance to cifenline, an investigational Class I agent. METHODS: Forty patients with chronic ventricular premature depolarizations (VPDs) underwent dose-ranging studies with cifenline, an investigational Class I antiarrhythmic agent. Patients had a minimum of 30 VPDs/h detected by ambulatory electrocardiographic (ECG) monitoring over a 48-hour baseline placebo lead-in period. Twenty-two patients (55 percent) who initially responded received long-term cifenline therapy. Ambulatory ECG monitoring over 24 hours was repeated during active cifenline therapy at three-month intervals and during placebo reintroduction at six-month intervals. RESULTS: After an average follow-up of 28 months, VPD frequency during cifenline therapy was similar to that during initial baseline placebo therapy in 8 of the 22 patients (36 percent) who initially responded. Placebo reintroduction following cifenline failure showed a VPD frequency similar to that with active therapy. All patients had further cifenline dosage increases without success. Plasma cifenline concentrations increased in all patients and were in the high therapeutic range. All 8 patients were switched to other Class I antiarrhythmic agents with successful VPD suppression during treatment with the first alternative drug. CONCLUSIONS: We conclude that antiarrhythmic resistance occurred with cifenline in these patients as (1) initial efficacy was established for a minimum of two years, (2) VPD frequency was similar during cifenline therapy and placebo reintroduction, (3) cifenline therapy failure continued despite further dosage titration, and (4) alternative Class I antiarrhythmic therapy was successful in all patients. Repeat intermittent ambulatory ECG monitoring is necessary not only to assess the continued need for antiarrhythmic drug therapy, but also to establish continued long-term efficacy.
Adult↗
Randomized, controlled trial of transdermal clonidine for smoking cessation.
OBJECTIVE: To determine the efficacy and safety of clonidine versus placebo in smoking cessation. DESIGN: Single-center, randomized, double-blind, parallel-design comparison of transdermal clonidine with behavior modification, transdermal clonidine without behavior modification, placebo with behavior modification, and placebo without behavior modification. SETTING: Outpatient, university-based ambulatory care facility. PATIENTS: One hundred fifty generally healthy, highly nicotine-dependent cigarette smokers. INTERVENTION: Clonidine was given as the transdermal patch initiated 72 hours prior to smoking-cessation attempts and continued for six weeks thereafter. Clonidine was given at a dose of 0.2 mg/d for patients weighing more than 150 pounds (> 67.5 kg) and at a dose of 0.1 mg/d for patients weighing less than 150 pounds (< 67.5 kg). Behavior modification consisted of a total of 12 one-hour structured group training sessions. Patients not receiving behavior modification received printed material, which included the "Help Quit Kit" and the "I Quit Kit" from the American Cancer Society. MAIN OUTCOME MEASURES: Smoking-cessation rates were assessed at 6, 12, 24, and 52 weeks of follow-up. In addition, adverse reactions to clonidine or placebo were evaluated. RESULTS: Clonidine with behavior modification was statistically superior to the other three treatment groups but only at 6 weeks of follow-up. There were no differences in smoking-cessation rates among any of the treatment groups at any other follow-up intervals. Patients receiving behavior modification, regardless of whether they received clonidine, had better quit rates than patients not receiving behavior modification at all follow-up times except 52 weeks. Women receiving clonidine had significantly better quit rates than men receiving clonidine at all follow-up visits. Clonidine was associated with a significantly higher incidence of adverse effects than placebo (52 vs. 11 percent). However, the number of smokers withdrawing from the study was not greater with clonidine compared with placebo (9 vs. 7 percent, respectively). CONCLUSIONS: Clonidine is probably not effective as a pharmacologic adjunct to behavior modification in smoking cessation. It may have a potential role in women smokers who do not respond to or cannot tolerate more traditional smoking-cessation therapies.
Administration, Cutaneous↗
Pharmacology of the class III antiarrhythmic agent sematilide in patients with arrhythmias.
Sematilide, a close structural analog of N-acetylprocainamide, prolongs cardiac action potentials in vitro, whereas it does not depress maximum action potential upstroke slope, a "class III" action. This report outlines an evaluation of the clinical pharmacologic actions of sematilide in 14 patients with chronic high-frequency nonsustained ventricular arrhythmias. In all, 36 intravenous infusions (range 0.15 to 1.5 mg/kg over 15 minutes) were administered in a dose-ranging, placebo-controlled study design. Sematilide prolonged rate-corrected QT (QTc) in a dose- and concentration-related fashion, did not alter PR or QRS, and slowed heart rate at high concentrations (greater than or equal to 2 micrograms/ml). The relations between dose and total area under the time-concentration curve, dose and peak plasma concentration, and peak plasma concentration and increase in QTc were linear (r = 0.66 to 0.92; p less than 0.001). QTc increases of approximately equal to 25% were seen at plasma concentrations of approximately equal to 2.0 micrograms/ml. The mean elimination half-life (+/- SD) was 3.6 +/- 0.8 hours, and most of a dose (77 +/- 13%) was recovered unchanged in the urine. Plasma concentrations greater than or equal to 0.8 micrograms/ml suppressed arrhythmias (5 patients) or aggravated them (3), including 1 patient who needed cardioversion for an episode of torsades de pointes (2.7 micrograms/ml). Thus, sematilide exerts class III actions in patients. Further studies to evaluate the role of this antiarrhythmic mode of action should be conducted at doses designed to limit QTc increases.
Anti-Arrhythmia Agents↗
Impact of chronic oral H2-antagonist therapy on left ventricular systolic function and exercise capacity.
It has been suggested that H2-antagonists may adversely affect left ventricular systolic function. To assess the effects of cimetidine, famotidine, and ranitidine on exercise capacity and left ventricular systolic function, the authors conducted a randomized, double-blind, four-way crossover study in 15 healthy male volunteers with placebo control. Each subject underwent a maximal upright treadmill exercise test, aerobic metabolic assessment, and two-dimensional stress echocardiography on six separate occasions. The initial two treadmill exercise tests with aerobic metabolic assessment and stress echocardiography were performed to minimize the learning effect. In the final four evaluations, subjects were randomized to receive 7 days of oral treatment with cimetidine 400 mg twice daily, famotidine 40 mg daily, ranitidine 150 mg twice daily, and placebo. A comparison of exercise tests, aerobic metabolic assessment, and stress echocardiography results found no significant differences between any of the H2-antagonists and placebo. In addition, there were no significant differences in test results between cimetidine, famotidine, and ranitidine. Specifically, exercise treadmill time, maximal oxygen consumption, respiratory quotient, maximal exercise systolic and diastolic blood pressure, maximal exercise heart rate, left ventricular end-diastolic dimension, left ventricular end-systolic dimension, and ejection fraction were not different between treatments. The authors conclude that 7 days of oral treatment with cimetidine, famotidine, or ranitidine has no deleterious effect on exercise capacity or left ventricular systolic function in healthy subjects.
Administration, Oral↗
Impact of food on the bioavailability of encainide.
The bioavailability of drugs that undergo extensive presystemic hepatic metabolism may be increased by concomitant ingestion with food. The effect of food on the bioavailability of encainide, a class IC antiarrhythmic agent, was evaluated in 14 healthy subjects in this randomized crossover study. The subjects received encainide 35 mg every 8 hours for 7 days and were randomized to receive their test dose of encainide with food or after an overnight fast. Encainide area-under-the-concentration versus time curve (AUCs) were detectable in 3 of 14 subjects after fasting and in 7 of 14 after feeding. Although food increased the mean encainide AUC by more than threefold, this increase did not reach statistical significance because of the large number of subjects with indeterminate encainide AUCs. Food did significantly increase the AUC of O-demethyl-encainide (ODE), but not the AUC of methoxy-O-demethyl-encainide (MODE). Despite the increase in ODE AUC, no significant effect on the surface electrocardiogram 2 hours after dose administration could be detected. Food may increase the bioavailability of encainide and one of its active metabolites (ODE). The clinical relevance of this pharmacodynamic effect warrants further evaluation.
Adult↗
Efficacy and safety of early versus late initiation of warfarin during heparin therapy in acute thromboembolism.
There is no universally accepted approach to the initiation of systemic anticoagulant therapy. In an open, randomized study, two anticoagulant regimens that differed only in the timing of warfarin therapy after the start of heparin were compared. We randomized 119 patients with acute thromboembolic events to receive warfarin either within 48 hours of the start of heparin (early group, n = 63) or 96 hours or later after the start of heparin (late group, n = 56). Heparin was given as a 5000 IU bolus as a constant infusion titrated to maintain the activated partial thromboplastin time at 1.5 to 2 times control values. Warfarin was started at 10 mg daily for 3 days and the dose was titrated to maintain the prothrombin time at 1.2 to 1.5 times control values. There were no significant differences between the early and late warfarin groups with regard to age, sex, indication for anticoagulation, heparin dose, mean activated partial thromboplastin time during heparin, warfarin dose at discharge, length of warfarin therapy before discharge, bleeding, recurrent thromboembolic events, or mortality rates. Time to the start of warfarin after heparin was 31 hours and 108 hours in the early and late groups, respectively. Length of hospitalization, hospital costs, and the incidence of heparin-induced infusion phlebitis and thrombocytopenia were significantly less in the early group compared with the late group. Early initiation of warfarin after heparin is safer, less expensive, and as effective as the late initiation of warfarin.
Aged↗
Comparison of adenosine and exercise thallium-201 single-photon emission computed tomography (SPECT) myocardial perfusion imaging. The GE SPECT Multicenter Adenosine Study Group.
Pharmacologic stress with dipyridamole has provided useful diagnostic, as well as prognostic, information in patients undergoing thallium-201 myocardial perfusion imaging. With its ultrashort half-life and a potent and consistent vasodilator effect, adenosine may be the coronary vasodilator of choice with myocardial perfusion imaging. Fifty-one healthy subjects and 93 patients with suspected coronary artery disease constituted the study group. In this multicenter study the comparative safety and diagnostic efficacy of single-photon emission computed tomography (SPECT) thallium imaging during adenosine-induced coronary hyperemia was compared with exercise treadmill stress. There was a mean increase in heart rate of 37% and a mean decrease in diastolic blood pressure of 5% during the adenosine infusion of 140 micrograms/kg per min for 6 min. Adenosine infusion was well tolerated in 95% of the subjects. Side effects requiring intervention occurred in seven subjects (5%). None of the subjects experienced a life-threatening complication. The sensitivity, specificity and predictive accuracy for detection of coronary artery disease with use of quantitative analysis was 83%, 87% and 84% for adenosine SPECT and 82%, 80% and 81% for exercise SPECT studies, respectively. Most false negative results with adenosine, as well as exercise SPECT studies, occurred in patients with single-vessel disease. The first-order concordance (no defect vs. defect) and second-order concordance (no defect vs. irreversible vs. reversible defect) was 89% and 78% between the two studies, respectively. Thus, the results of adenosine SPECT imaging are highly concordant with exercise SPECT thallium imaging. Adenosine SPECT thallium imaging provides a safe and highly accurate imaging mode for the detection of coronary artery disease.
Adenosine↗
Comparative pharmacodynamics of intravenous lidocaine in patients with acute and chronic ventricular arrhythmias.
OBJECTIVE: To evaluate the pharmacodynamics of intravenous lidocaine in patients with acute-onset and chronic ventricular arrhythmias. DESIGN: Open-label, pharmacodynamic evaluation. SETTING: Private, university-affiliated, hospital coronary-care unit. PATIENTS: Twenty cardiac patients with acute-onset ventricular ectopy and 20 with chronic ventricular ectopy. INTERVENTIONS: Intravenous lidocaine was administered to all patients as a 1-mg/kg bolus, a 0.5-mg/kg bolus, and a 2.8-mg/min constant infusion for 48 hours. MAIN OUTCOME MEASURES: Changes in ventricular premature beat (VPB) frequency against total treatment period frequency and by an hour-to-hour assessment of changes in VPB frequency compared with total baseline frequencies. Response was defined as greater than or equal to 80 percent total VPB reduction, greater than or equal to 90 percent paired VPB reduction, and total abolition of nonsustained ventricular tachycardia events. RESULTS: A statistically significant difference in the pharmacodynamic effects of lidocaine were observed during the first eight hours of treatment in patients with acute-onset and chronic VPBs. The number of patients with acute-onset VPBs who responded to lidocaine in the first hour of treatment did not change significantly over the remaining hours of treatment. Response to lidocaine was less in patients with chronic VPBs than in patients with acute-onset VPBs. The response rate to lidocaine was significantly less during the first eight hours in patients with chronic VPBs than in patients with acute-onset VPBs. Following eight hours of treatment, the response rates between acute-onset and chronic VPB patients were not significantly different. Mean lidocaine plasma concentrations were not different between the groups. In addition, there were no significant differences in the incidence of adverse effects between the two groups. CONCLUSIONS: The onset of antiarrhythmic effect as measured by suppression of ventricular ectopy is delayed in patients with chronic VPBs compared with patients with acute-onset VPBs. Decisions about lidocaine response in patients with chronic VPBs cannot be made accurately in the first eight hours of therapy.
Acute Disease↗
Thallium-201 myocardial imaging in patients with coronary artery disease: comparison of intravenous adenosine and oral dipyridamole.
OBJECTIVE: To compare thallium-201 (201Tl) myocardial perfusion imaging following intravenous adenosine and oral dipyridamole. DESIGN: Open-label, randomized, comparison. SETTING: Outpatient, university-affiliated clinic. PATIENTS: Fifteen patients with angiographically documented coronary artery disease. INTERVENTIONS: Planar 201Tl myocardial perfusion imaging following both intravenous adenosine 140 micrograms/kg/min for six minutes and oral dipyridamole suspension 300 mg. MAIN OUTCOME MEASURES: A comparison between adenosine and dipyridamole was made in the following areas: concordance in interpretation of 201Tl scintigrams, cardiac and noncardiac 201Tl uptake and clearance, hemodynamic and electrocardiographic changes, and adverse effects. RESULTS: The scintigraphic studies showed perfusion defects in 13 patients (87 percent) after dipyridamole and in 15 patients (100 percent) after adenosine. 201Tl uptake and clearance were quantitated in nine myocardial segments and in four extracardiac segments in each patient. 201Tl uptake was not significantly different between adenosine and dipyridamole studies in most cardiac regions. Extracardiac 201Tl uptake was significantly less in the liver and splanchnic regions following adenosine compared with dipyridamole. 201Tl clearance was not significantly different following adenosine and dipyridamole except in the anterolateral region in the anterior view. Hemodynamic changes following administration of intravenous adenosine and oral dipyridamole were not significantly different. Adverse effects were more common with adenosine than with dipyridamole. Adverse effects with adenosine were transient; however, adverse effects with dipyridamole were prolonged and required reversal with aminophylline in 2 patients. No patients required termination of the adenosine infusion or administration of aminophylline. CONCLUSIONS: These preliminary data suggest that adenosine 201Tl imaging may be a useful alternative to dipyridamole 201Tl imaging. Although adenosine produces more frequent adverse effects, they are generally better tolerated than those associated with dipyridamole.
Adenosine↗
Effect of buspirone on withdrawal symptoms associated with smoking cessation.
BACKGROUND: Preliminary information suggests that buspirone hydrochloride ameliorates symptoms of nicotine withdrawal. In a double-blind, randomized, placebo-controlled trial, we determined the effects of buspirone on the withdrawal symptoms associated with smoking cessation in 40 long-term cigarette smokers. METHODS: Subjects were randomized to 4 weeks of treatment with either buspirone (n = 20) or placebo (n = 20). Subjects were instructed to maintain their usual cigarette intake during the first 21 days of treatment and to cease smoking on day 22 of treatment. Withdrawal symptoms were subjectively rated before and during smoking cessation. RESULTS: Before smoking cessation, there were no significant differences in the intensity of any withdrawal symptom between the buspirone- and placebo-treated subjects, with the exception of a significantly higher rating for drowsiness in the buspirone group. During the smoking cessation period, the ratings for craving, anxiety, irritability, restlessness, and sadness were significantly lower in the buspirone group than the placebo group. There were no significant differences between the groups in their ratings for hunger, inability to concentrate, or drowsiness. Fifteen buspirone-treated subjects and nine placebo-treated subjects were able to abstain from cigarettes during the entire 7-day smoking cessation period. No subject dropped out of the study for perceived drug side effects. Eight buspirone-treated subjects and five placebo-treated subjects reported side effects, all of which were mild. CONCLUSIONS: Buspirone ameliorated most of the short-term withdrawal symptoms associated with smoking cessation. Further controlled studies will be needed to define the benefit in smoking cessation.
Adult↗