By intramuscular injection, or by slow intravenous injection. For Adult. 25–30 micrograms/kg every 6 hours if required; usual dose 1.5–2.5 mg every 6 hours if required, intravenous injection to be administered into a large vein, only use intramuscular route when oral and intravenous routes not possible. and a medication induced long qt interval ( now resolved) was told I am fine , but I know nearly all my ecg show non specific t wave changes , however I had to have an ecg to check qt before starting on a new med ( I just moved to new town , new doc etc) ecg computer printed out the words consider possible prior heart attack wich the doctor told me. reports of QTc prolongation involve ami-triptyline and maprotiline.9 Risk factors include demographics (eg, female sex, age), personal or family history (congeni-tal long QT syndrome, cardiovascular dis-ease), and concurrent conditions or drug use, particularly those associated with QTc prolongation.3 Desipramine and nortripty- Drugs associated with QT Prolongation, QTc prolongation Long QT syndrome incidence is increasing in general population. A careful pre-, peri- and post-operative management is needed for patients with this syndrome because of the risk of Torsades de Pointes and malignant arrhythmias. The available data regarding. Der obere Grenzwert der QTc beträgt 450 msec. für Männer beziehungsweise 460 msec. für Frauen8). Die Beziehung zwischen Dauer der QTc und dem Auftreten von Torsa-de de pointes-Tachykardien ist jedoch nicht linear. Beim kongenitalen Long-QT Syndrom werden grosse intrafamiliäre Variationen der QTc beobachtet. Weiterhin ist die QTc should be given to dose reduction of QT prolonging drugs or changing to an alternative non QT prolonging drug. Prolonged QTc Interval 500 ms. A QTc interval 500 ms is clinically significant and likely to confer an increased risk of arrhythmia. Any drugs which prolong the QT interval should be reviewed immediately. 4,5,6,7 Background: Recent regulatory and clinical concerns have brought into sharp focus antipsychotic drug-induced QTc interval prolongation, torsades de pointes, and sudden cardiac death. Several new generation (atypical) antipsychotic drugs have either been withdrawn from clinical use or delayed in reaching the marketplace due to these concerns. Practice Points. Screen patients for risk factors for prolonged QTc interval, such as congenital long QT syndrome, family history of cardiac conduction abnormalities, and previous occurrences of medication-mediated QTc prolongation.; Obtain baseline and steady state ECG when initiating high-risk agents, particularly when administering combination therapy. Intramuscular Haloperidol or Lorazepam and QT Intervals in Schizophrenia Article in The Journal of Clinical Pharmacology 44(10):1173-84 · November 2004 with 430 Reads How we measure 'reads'.