Metoprolol

INTRODUCTION

Indications

Hypertension. Angina pectoris. Prevention of MI and decreased mortality in patients with recent MI. Management of stable, symptomatic (class II or III) heart failure due to ischemic, hypertensive, or cardiomyopathic origin (may be used with ACE inhibitors, diuretics, and/or digoxin; Toprol-XL 25 mg only).

Unlabeled Use: Ventricular arrhythmias/tachycardia. Migraine prophylaxis. Tremors. Aggressive behavior. Drug-induced akathisia. Anxiety.

Action

Blocks stimulation of beta₁ (myocardial)–adrenergic receptors. Does not usually affect beta₂ (pulmonary, vascular, uterine)–adrenergic receptor sites. Therapeutic Effects: Decreased blood pressure and heart rate. Decreased frequency of attacks of angina pectoris. Decreased rate of cardiovascular mortality and hospitalization in patients with heart failure.

Adverse Reactions/Side Effects

CNS: fatigue, weakness, anxiety, depression, dizziness, drowsiness, insomnia, memory loss, mental status changes, nervousness, nightmares. EENT: blurred vision, stuffy nose. Resp: bronchospasm, wheezing. CV: BRADYCARDIA, CHF, PULMONARY EDEMA, hypotension, peripheral vasoconstriction. GI: constipation, diarrhea, drug-induced hepatitis, dry mouth, flatulence, gastric pain, heartburn, increased liver function studies, nausea, vomiting. GU: erectile dysfunction, decreased libido, urinary frequency. Derm: rashes. Endo: hyperglycemia, hypoglycemia. MS: arthralgia, back pain, joint pain. Misc: drug-induced lupus syndrome.

PHYSICAL THERAPY IMPLICATIONS

Examination and Evaluation

• Assess heart rate, ECG, and heart sounds, especially during exercise (See Appendices G, H). Although intended to treat certain arrhythmias, this drug can unmask or precipitate new arrhythmias (proarrhythmic effect). Report an unusually slow heart rate (bradycardia) or signs of other arrhythmias, including palpitations, chest pain, shortness of breath, fainting, and fatigue/weakness.

• Watch for signs of CHF and pulmonary edema, including dyspnea, rales/crackles, weight gain, peripheral edema, and jugular venous distention. Report any new or increased signs of heart failure, but also determine if drug therapy is effective in reducing these symptoms in patients with preexisting heart failure.

• Assess blood pressure periodically and compare to normal values (See Appendix F) to help document antihypertensive effects. Report low blood pressure (hypotension), especially if patient experiences dizziness or syncope.

• If used to prevent migraine headaches, monitor the incidence and severity of migraine attacks to document whether this drug is successful in helping manage the patient's pain.

• Assess exercise tolerance and episodes of angina pectoris. Document improvements in these variables, but also report any decline in exercise tolerance or increased frequency/severity of anginal attacks.

• Assess symptoms of bronchospasm (wheezing, coughing, tightness in chest). Perform pulmonary function tests to quantify suspected changes in ventilation and respiration (See Appendices I, J, K). Repeated or prolonged bronchoconstriction may require a change in dose or medication.

• Monitor signs of peripheral vasoconstriction, such as extreme coldness in the hands and feet, cyanosis, ...