CASE FILE-6

A 70-Year-old man is seen in follow-up at your office after he has been hospitalized for a myocardial infarction. He underwent successful angioplasty and is currently asymptomatic. Prior to his MI, he was not on medications. He is not a smoker and is not diabetic. During his hospitalization, he was noted to have persistently elevated blood pressure readings. He had asthma as a child, but has not had any recent wheezing episodes . While in the hospital, he was started on oral metoprolol.

Questions 1. Metoprolol is selective for which

adrenoceptor?2. What effects do agents such as metoprolol

have on the cardiovascular system?3. In which organ is metoprolol primarily

metabolized?4. Why must beta adrenergic antagonists be

used with caution in asthmatics?

Summary A 70-year-old hypertensive man

with a childhood history of asthma had a recent myocardial infarction and is prescribed metoprolol

Adrenoceptor selectively antagonized by metaprolol

Beta 1

Effect of beta adrenoceptor antagonists on the cardiovascular system

Reduction of sympathetic-stimulated increases in heart rate, contractility and cardiac output

Lower BP as a result of effects on heart, renin-angiotensin system, and CNS

Increased atrioventricular (AV) conduction time and refractoriness.

Organ in which metoprolol is metabolized

Liver

Reason for caution in use in asthhmaticsBlockade of beta 2 adrenoceptor in

bronchial smooth muscle may cause increased airway resistance and bronchospasm