rmation to be gained through use of intravenous dipyridamole thallium imaging (see indications and usage noting the rate of false positive and false negative results) must be weighed against the risk to the patient. patients with a history of unstable angina may be at a greater risk for severe myocardial ischemia. patients with a history of asthma may be at a greater risk for bronchospasm during dipyridamole injection use. when thallium myocardial perfusion imaging is performed with intravenous dipyridamole, parenteral aminophylline should be readily available for relieving adverse events such as bronchospasm or chest pain. vital signs should be monitored during, and for 10-15 minutes following, the intravenous infusion of dipyridamole and an electrocardiographic tracing should be obtained using at least one chest lead. should severe chest pain or bronchospasm occur, parenteral aminophylline may be administered by slow intravenous injection (50-100 mg over 30-60 seconds) in doses ranging from 50 to 250 mg. in the case of severe hypotension, the patient should be placed in a supine position with the head tilted down if necessary, before administration of parenteral aminophylline. if 250 mg of aminophylline does not relieve chest pain symptoms within a few minutes, sublingual nitroglycerin may be administered. if chest pain continues despite use of aminophylline and nitroglycerin, the possibility of myocardial infarction should be considered. if the clinical condition of a patient with an adverse event permits a one-minute delay in the administration of parenteral aminophylline, thallium-201 may be injected and allowed to circulate for one minute before the injection of aminophylline. this will allow initial thallium perfusion imaging to be performed before reversal of the pharmacologic effects of dipyridamole on the coronary circulation.

discoloration prior to administration, whenever solution and container permit.

ents within the study included: cardiovascular system electrocardiographic abnormalities unspecified (0.8%), arrhythmia unspecified (0.6%), palpitation (0.3%), ventricular tachycardia (0.2%-see warnings ), bradycardia (0.2%), myocardial infarction (0.1%–see warnings ), av block (0.1%), syncope (0.1%), orthostatic hypotension (0.1%), atrial fibrillation (0.1%), supraventricular tachycardia (0.1%), ventricular arrhythmia unspecified (0.03%–see warnings ), heart block unspecified (0.03%), cardiomyopathy (0.03%), edema (0.03%). central and peripheral nervous system hypothesia (0.5%), hypertonia (0.3%), nervousness/anxiety (0.2%), tremor (0.1%), abnormal coordination (0.03%), somnolence (0.03%), dysphonia (0.03%), migraine (0.03%), vertigo (0.03%). gastrointestinal system dyspepsia (1%), dry mouth (0.8%), abdominal pain (0.7%), flatulence (0.6%), vomiting (0.4%), eructation (0.1%), dysphagia (0.03%), tenesmus (0.03%), appetite increase (0.03%). respiratory system pharyngitis (0.3%), bronchospasm (0.2%–see warnings ), hyperventilation (0.1%), rhinitis (0.1%), coughing (0.03%), pleural pain (0.03%). other myalgia (0.9%), back pain (0.6%), injection site reaction unspecified (0.4%), diaphoresis (0.4%), asthenia (0.3%), malaise (0.3%), arthralgia (0.3%), injection site pain (0.1%), rigor (0.1%), earache (0.1%), tinnitus (0.1%), vision abnormalities unspecified (0.1%), dysgeusia (0.1%), thirst (0.03%), depersonalization (0.03%), eye pain (0.03%), renal pain (0.03%), perineal pain (0.03%), breast pain (0.03%), intermittent claudication (0.03%), leg cramping (0.03%). in additional postmarketing experience, there have been rare reports of allergic reaction including urticaria, pruritus, dermatitis and rash. adverse

n fully elucidated, but may result from inhibition of uptake of adenosine, an important mediator of coronary vasodilation. the vasodilatory effects of dipyridamole are abolished by administration of the adenosine receptor antagonist theophylline. how dipyridamole-induced vasodilation leads to abnormalities in thallium distribution and ventricular function is also uncertain but presumably represents a “steal” phenomenon in which relatively intact vessels dilate and sustain enhanced flow, leaving reduced pressure and flow across areas of hemodynamically important coronary vascular constriction. pharmacokinetics and metabolism plasma dipyridamole concentrations decline in a triexponential fashion following intravenous infusion of dipyridamole, with half-lives averaging 3-12 minutes, 33-62 minutes and 11.6-15 hours. two minutes following a 0.568 mg/kg dose of dipyridamole injection administered as a 4-minute infusion, the mean dipyridamole serum concentration is 4.6 ± 1.3 mcg/ml. the average plasma protein binding of dipyridamole is approximately 99%, primarily to α1-glycoprotein. dipyridamole is metabolized in the liver to the glucuronic acid conjugate and excreted with the bile. the average total body clearance is 2.3-3.5 ml/min/kg, with an apparent volume of distribution at steady state of 1-2.5 l/kg and a central apparent volume of 3-5 liters.