Inquiries about Biotechnological agents over a 15 year period: a descriptive study

August 2015 e89 increased repolarization beyond the increase seen with DHE; in contrast, no TdP was induced. In cAVB dogs, 0.33 mg/kg/5 min DHE (plasma level 1.2 μ M) increased QT duration by 48 ± 10% (P < 0.05*) and induced TdP in 3/4 dogs, which was comparable to dofetilide in the same animals. Surprisingly, a higher dose of DHE induced a similar increase in QT duration (51 ± 10%*) but this did not culminate in TdP (0/4), while dofetilide induced TdP in 3/4. Conclusions: DHE blocks IKr, which is responsible for prolonged repolarization and pro-arrhythmic effects. However, DHE seems to affect other ion currents and/or has extra cardiac effects that could limit its pro-arrhythmic potential and explain the self-protecting properties observed at higher concentrations.