Atropine is a tertiary amine. The naturally occurring levorotatory form is active, but the commercial mixture is racemic (Figure 13-1).
As a premedication, atropine is administered intravenously or intramuscularly in a range of 0.01-0.02 mg/kg, up to the usual adult dose of 0.4-0.6 mg. Larger intravenous doses up to 2 mg may be required to completely block the cardiac vagal nerves in treating severe bradycardia. Atropine sulfate is available in a multitude of concentrations.
has particularly potent effects on the heart and bronchial smooth muscle and is the most efficacious anticholinergic for treating bradyarrhythmias. Patients with coronary artery disease may not tolerate the increased myocardial oxygen
demand and decreased oxygen
supply associated with the tachycardia caused by atropine
. A derivative of atropine
bromide, is available in a metered-dose inhaler for the treatment of bronchospasm. Its quaternary ammonium structure significantly limits systemic absorption. Ipratropium
solution (0.5 mg in 2.5 mL) seems to be particularly effective in the treatment of acute chronic obstructive pulmonary disease when combined with a β-agonist drug (eg, albuterol
). The central nervous system effects of atropine
are minimal after the usual doses, even though this tertiary amine can rapidly cross the blood-brain barrier. Atropine
has been associated with mild postoperative memory deficits, and toxic doses are usually associated with excitatory reactions. An intramuscular dose of 0.01-0.02 mg/kg reliably provides an antisialagogue effect. Atropine
should be used cautiously in patients with narrow-angle glaucoma, prostatic hypertrophy, or bladder-neck obstruction.