H2blockers and heart

Q; 42 years old male is admitted to ICU with Small Bowel Obstruction. Patient is made NPO. Also, famotidine is prescribed as an intravenous bid dose. During the administration of IV famotidine, the patient became hypotensive, and cardiac arrhythmia was noted on the monitor, which degenerated into cardiac arrest. H2-blockers (H2B) tend to cause? - select one

A) Sinus bradycardia

B) Sinus tachycardia

Answer: A

The use of anti-ulcer medications is common in the ICU. Although not common, rapid infusion of H2B may cause sinus bradycardia, hypotension, atrioventricular (AV) blocks, prolongation of the QT interval, and cardiac arrest. If possible, it is preferred to use the oral route as its bioavailability is not much affected by food, though first-pass metabolism may cause some decreased effects. Unfortunately, our patient in question can not have it. In such cases, slow administration is preferred. 

Risk factors for cardiac arrest are rapid intravenous infusion, high dose, renal or hepatic dysfunction(delays clearance), and underlying heart condition.

#pharmacology

#cardiology

References:

1. Hinrichsen H, Halabi A, Kirch W. Clinical aspects of cardiovascular effects of H2-receptor antagonists. Eur J Clin Invest 1995; 25 Suppl 1:47.

2. Lee KW, Kayser SR, Hongo RH, et al. Famotidine and long QT syndrome. Am J Cardiol 2004; 93:1325.