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Adverse Drug Reactions - Part I

Course Number: 536

ADRs Affecting the Cardiovascular System

Hypotension (ADR #18) was the most common ADR related to the cardiovascular system in 2008.15 It is defined as blood pressure (BP) below normal for the individual. Orthostatic hypotension is a decline from baseline of ≥ 20 mm Hg in the systolic BP and/or a decline of ≥ 10 mm Hg in the diastolic BP with symptoms of cerebral ischemia (syncope) following postural change.14,36 Common drugs that produce orthostatic hypotension include diuretics, α1 and β1-receptor blockers, nitrates, digitalis, ACE-inhibitors, and calcium channel blockers.36

Syncope is defined as the sudden brief loss of consciousness due to decreased cerebral perfusion.14,37 In a young adult it is usually precipitated by stressful situations (e.g., prolonged standing, crowded places, hot environment, severe pain, extreme fatigue and stress) followed by vasodilatation (sympathetic withdrawal) and bradycardia (parasympathetic activity). Prodromal signs and symptoms consist of blurred vision, diaphoresis, nausea, dizziness, weakness and eventual bradycardia, hypotension, and loss of consciousness. More worrisome causes of syncope include cardiovascular disorders (e.g., dysrhythmia, postural hypotension), hypoglycemia, anemia, or cerebrovascular insufficiency.37

Palpitation (ADR #22) is a general term used by patients to describe an unpleasant awareness of forceful, rapid, or irregular heartbeat.8,38, The potential etiologies are extensive and include cardiac conditions, psychiatric, metabolic disorders, medications, and illicit drugs. Importantly, palpitations may indicate the presence of an arrhythmia. Atrial fibrillation is the most common arrhythmia resulting in hospitalization and is associated with an increased risk of stroke. All patients with palpitations should be medically evaluated to determine the etiology.39

Arrhythmia may result from drug-induced abnormal impulse generation or abnormal impulse conduction in the heart, and potentially lead to life-threatening torsades de pointes.39 Implicated drugs include amphetamines, antiarrhythmics, anticholinergics, antihistamines, decongestants, diuretics, fluoroquinolones, macrolides antibiotics, phenothiazines, protease inhibitors, SSRIs, sympathomimetics, tricyclic antidepressants, and vasodilators.39