Cardiac toxicity after oral phenytoin overdose in an otherwise healthy patient has not been reported and, if observed, requires assessment for other causes (e.g., hypoxia and other drugs). Cardiovascular complications have been almost entirely limited to cases of intravenous administration. Complications include hypotension with decreased peripheral vascular resistance, bradycardia, conduction delays progressing to complete AV nodal block, ventricular tachycardia, primary ventricular fibrillation, and asystole. Electrocardiographic changes include increased PR interval, widened QRS interval,and altered St-segments and T-waves. Bradycardia, hypotension, and syncope in healthy volunteers have been reported even after small undiluted intravenous doses. Some of these complications can be attributed to rapid intravenous administration of the preparation containing propylene glycol and are avoidable with cautious administration ( T.a.ble.,.1Z2.-3). Even slowly administered intravenous phenytoin (less than 25 mg/min) has also been reported to cause arrest in critically ill patients receiving dopamine infusions to support blood pressure.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.