Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0012833 (dizziness)
 9,689 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Exercise myocardial-thallium scintigraphy plays a fundamental role in the diagnosis of coronary artery disease. Once exercise is not always feasible, pharmacological stress became a possible alternative. The authors review the mechanism of action, administrations protocols, indications and side effects of the drugs used for this purpose: dipyridamole, adenosine and dobutamine. Dipyridamole causes coronary hyperemia by increasing the interstitial levels of endogenous adenosine. Perfusion defects result from the mismatch of coronary reserve in different coronary territories. The drug administration is classically performed with a 0.142 mg/kg/min dosage e.v. for 4 minutes, total of 0.56 mg/kg. It is possible to use a greater dose of 0.84 mg/kg e.v. for 10 minutes, increasing sensitivity without loss of specificity for diagnosis of coronary artery disease. Oral dipyridamole protocols with 300 and 400 mg were used with similar results for sensitivity and specificity. The oral protocol has the disadvantage of delayed onset and longer action. Including several dipyridamole studies, 87% was obtained for sensitivity and 84% for specificity, in the diagnosis of CAD. Dipyridamole scintigraphy has been applied to myocardial infarction risk stratification, cardiac risk evaluation of patients proposed to noncardiac surgery and therapeutic efficacy evaluation of reperfusion techniques (angioplasty and surgery). The secondary effects of dipyridamole are frequent, however mild and well tolerated. They occur in half the patients, the most frequent, facial flushing (2%), dizziness (5%), nausea (4%), vomiting (1%), headaches (11%) and chest pain (26%). Some important complications were reported although rare: myocardial infarction, ventricular fibrillation and bronchospasm.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Role of pharmacologic stimulation with myocardial perfusion scintigraphy in the evaluation of patients with ischemic cardiopathy]. 129 Jun 55

Dipyridamole is a well known anti-aggregating agent characterized by poor water solubility as well as scant and variable bioavailability. Recently, the compound was complexed with beta-cyclodextrin forming a molecular encapsulation resulting in better oral absorption and stronger biological activities in animals. In the present study, a randomized double blind cross-over comparison between dipyridamole-beta-cyclodextrin complex (dip-beta-CD) and dipyridamole was performed in 12 healthy subjects after single (75mg) and multiple oral treatments (75mg TID). Dip-beta-CD showed better bioavailability and less interindividual variability than dipyridamole either after single or multiple doses. In particular, dip-beta-CD had a greater AUC and Cmax, and a smaller Tmax even at the steady state. In addition, 100% of the subjects receiving a single dose of dip-beta-CD, as compared to 66.7% of those treated with dipyridamole, had plasma levels superior to 1 microgram/ml (which is the supposed anti-aggregating threshold level). In contrast, 0 and 33.03% of the subjects showed plasma levels superior to 2.5 micrograms/ml (which might cause the appearance of side-effects) on the 7th day of the multiple treatment with dip-beta-CD and dipyridamole, respectively. In fact, the subjects presenting higher levels after uncomplexed dipyridamole also complained of headache and/or dizziness on occasion. No adverse side effects were reported for dip-beta-CD.
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PMID:Pharmacokinetics of dipyridamole-beta-cyclodextrin complex in healthy volunteers after single and multiple doses. 181 37

Dipyridamole thallium-201 imaging, using single-photon emission computed tomography, was evaluated for its safety and diagnostic efficacy in 109 patients with angiographically documented coronary artery disease and 35 normal subjects. The most common side effects after the intravenous administration of dipyridamole thallium-201 (0.56 mg/kg) included chest pain in 41 patients, dizziness in 20 patients, headache in 16 patients, and ST segment depression > or = 1 mm in 15 patients. Aminophylline was required to reverse the side-effects in 46 patients, and 45 of the 46 patients experienced complete relief of symptoms. Of the 109 patients with coronary artery disease, 104 had abnormal dipyridamole thallium images. The per patient sensitivity was 95%. Of the 35 normal subjects, 27 had normal thallium images. The per patient specificity was 77%. The sensitivity and specificity for the individual vessels were 84% and 87% for the left anterior descending artery, 67% and 97% for the left circumflex artery, and 89% and 85% for the right coronary artery, respectively. Dipyridamole thallium-201 imaging is a relatively safe noninvasive method and is an effective alternative to exercise thallium-201 scintigraphy for the diagnosis of coronary artery disease.
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PMID:Diagnosis of coronary artery disease using dipyridamole thallium-201 imaging. 763 92

Dipyridamole-induced coronary hyperemia with 201Tl myocardial perfusion scintigraphy can detect ischemic regions in individuals unable to perform adequate exercise, but it has several limitations. Symptom-limited exercise supplementation to intravenous dipyridamole can potentially overcome them, but the safety and diagnostic accuracy for this combination has not been established. Between 1987 and 1991, 441 consecutive patients were assessed for combined symptom-limited exercise test preceded by i.v. dipyridamole. Clinical records could not be obtained for 37 patients, and 40 patients were not exercised because they were unable; therefore 384 patients (mean age 58 +/- 9.8 yr, 278 men) underwent symptom-limited exercise preceded by 0.56 mg/kg of dipyridamole and followed by planar 201Tl perfusion scintigraphy. Following dipyridamole infusion, systolic blood pressure fell by 10 +/- 14 mmHg and heart rate increased by 8 +/- 11 bpm. Adverse effects were experienced by 77 people (dizziness in 44; headache in 11; nausea in 9; syncope in 2 and chest pain in 11). Exercise heart rate was 69% +/- 16% of predicted maximum and ST shift was -0.9 +/- 0.9 mm. Following exercise, seven patients required aminophylline (four after dizziness, two after headache, one after chest pain), which was uniformly successful. There were no episodes of prolonged chest pain, MI, death or serious arrhythmia. Safety was maintained for people with severe triple coronary artery disease, the elderly (> 70 yr) and those with significant pulmonary disease. Sensitivity was 95% for at least one with > 70% luminal stenosis and 94% for at least one with > 40% luminal stenosis. Specificity was 28% and 53% respectively. The addition of a symptom-limited exercise test to i.v. dipyridamole is safe for all groups of patients referred for 201Tl study.
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PMID:Safety and clinical utility of combined intravenous dipyridamole/symptom-limited exercise stress test with thallium-201 imaging in patients with known or suspected coronary artery disease. 825 87