Signs and Symptoms Overdosage of TOPROL-XL may lead to severe hypotension, sinus bradycardia, atrioventricular block, heart failure, cardiogenic shock, cardiac arrest, bronchospasm, impairment of consciousness coma, nausea, vomiting, and cyanosis. In vitro and in vivo animal studies have shown that it has preferential effect on beta1 adrenoreceptors, chiefly located in cardiac muscle. This medicine may cause some people to become cheap metoprolol online less alert than they are normally. Both formulations were given in dose range equivalent to 100-400 mg of immediate release metoprolol per day. In patients with angina pectoris, plasma concentration measured at hour is linearly related to the oral dose within the range of 50 to 400 mg. Report unresolved swelling of extremities, respiratory difficulty or new cough, unresolved fatigue, unusual weight gain, unresolved constipation, or unusual muscle weakness.