Abstract
Iatrogenic bleeding tendencies due to procainamide (PA) were observed in two male hemodialysis patients. One was a 55 year old patient who had been receiving 250 mg/day of PA for about one month for his supraventricular premature beats. Another was a 26 year old patient who had been receiving 750 mg/day of PA for about one year for his paroxysmal supraventricular tachycardia. Their prothrombin time, partial thromboplastin time and fibrinogen were within normal ranges in all. Serum levels of PA and N-acetyl PA (NAPA), an active metabolite of PA, were 1.5 μg/ml and 16.8 μg/ml in the former and 5.5 μg/ml and 42.0 μg/ml in the latter, respectively. In both cases, NAPA was markedly accumulated in the serum when compared with PA. Their bleeding tendencies disappearedd after the withdrawal of PA. Their platelet functions assessed by platelet aggregability were moderately to severely impaired when compared with those of male hemodialysis patients not receiving PA. This abnormal platelet aggregability was markedly improved after the withdrawal of PA. With the administration of PA (750 mg/day) to another patient on chronic hemodialysis for five days, platelet aggregability was suppressed moderately and it took two weeks after its withdrawal to return back to its pre-value. PA suppressed in vitro platelet aggregability at a final concentration of 50 μg/ml and severely at 500 μg/ml. The effect of NAPA was almost the same as that of PA. These data suggest that PA induces bleeding tendencies through its action on platelet function. In hemodialysis patients, PA should be administered with caref ull monitoring of serum levels of PA and NAPA or platelet aggregability because a marked accumulation of NAPA is always possible.
