Warnings & Precautions

Myocardial Ischemia—Fatal cardiac arrest, life-threatening ventricular arrhythmias, and myocardial infarction may result from the ischemia induced by pharmacologic stress agents. Cardiac resuscitation equipment and trained staff should be available before administering Lexiscan. If serious reactions to Lexiscan occur, consider the use of aminophylline, an adenosine antagonist, to shorten the duration of increased coronary blood flow induced by Lexiscan.

Sinoatrial (SA) and Atrioventricular (AV) Nodal Block—Adenosine receptor agonists, including Lexiscan, can depress the SA and AV nodes and may cause first-, second-, or third-degree AV block, or sinus bradycardia requiring intervention. In clinical trials, first-degree AV block (PR prolongation >220 msec) developed in 3% of patients within 2 hours of Lexiscan administration; transient second-degree AV block with 1 dropped beat was observed in 1 patient receiving Lexiscan. In postmarketing experience, third-degree heart block and asystole within minutes of Lexiscan administration have occurred.

Hypotension—Adenosine receptor agonists, including Lexiscan, induce arterial vasodilation and hypotension. In clinical trials, decreased systolic blood pressure (>35 mm Hg) was observed in 7% of patients, and decreased diastolic blood pressure (>25 mm Hg) was observed in 4% of patients, within 45 minutes of Lexiscan administration. The risk of serious hypotension may be higher in patients with autonomic dysfunction, hypovolemia, left main coronary artery stenosis, stenotic valvular heart disease, pericarditis or pericardial effusions, or stenotic carotid artery disease with cerebrovascular insufficiency. In postmarketing experience, syncope and transient ischemic attacks have been observed.

Bronchoconstriction—Adenosine receptor agonists, including Lexiscan, may cause bronchoconstriction and respiratory compromise. For patients with known or suspected bronchoconstrictive disease, chronic obstructive pulmonary disease (COPD) or asthma, appropriate bronchodilator therapy and resuscitative measures should be available prior to Lexiscan administration.

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