title: Fetal supraventricular tachycardia treated with high-dose quinidine: toxicity associated with marked elevation of the metabolite, 3(S)-3-hydroxyquinidine.
abstract: We observed a patient at 33 weeks' gestation who was administered exceptionally large doses of quinidine to treat a fetal supraventricular tachycardia. The patient had clinical evidence of quinidine toxicity at low to mid-therapeutic levels of quinidine, but markedly elevated levels of the metabolite 3(S)-3-hydroxyquinidine (3-hydroxyquinidine). This pattern is consistent with a "fast metabolism" of quinidine. There is substantial evidence that 3-hydroxyquinidine has pharmacologic activity. We conclude that elevated levels of 3-hydroxyquinidine can be associated with a clinically significant quinidine toxicity. This can occur in the presence of a nontoxic serum quinidine level. We also measured the levels of quinidine and 3-hydroxyquinidine in the amniotic fluid and cord blood. The levels in the cord blood were 31 and 27%, respectively, of those in a simultaneously drawn maternal blood sample.
mesh_terms: D000328:Adult; D000653:Amniotic Fluid / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D005260:Female; D005312:Fetal Blood / Q000032:analysis; D005315:Fetal Diseases / Q000188:drug therapy*; D005318:Fetal Heart / Q000187:drug effects; D006801:Humans; D009325:Nausea / Q000139:chemically induced; D011247:Pregnancy; D011802:Quinidine / Q000009:adverse effects* / Q000031:analogs & derivatives* / Q000378:metabolism / Q000627:therapeutic use; D013617:Tachycardia, Supraventricular / Q000188:drug therapy*; D014839:Vomiting / Q000139:chemically induced
chemical_list: C013569:3-hydroxyquinidine; D011802:Quinidine