Elongated QT Interval


  • Drugs which inc QT interval
  • Other antidepressants: tricyclics plus trazodone and venlafaxine.
  • Antibiotics:
  • Macrolides (erythromycin, clarithromycin, azithromycin).
  • Ampicillin.
  • Co-trimoxazole.
  • Quinolones (ciprofloxacin, levofloxacin, norfloxacin, moxifloxacin).
  • Antiarrhythmics including amiodarone, dronedarone, sotalol and quinidine.
  • Antipsychotics: all antipsychotics, but highest risk with haloperidol and pimozide.
  • Lithium, with greater risk if lithium levels are raised.
  • Methadone, especially doses above 100mg.
  • Antimalarials: mefloquine, chloroquine, artemether/lumefantrine.
  • Quinine: especially at higher doses.
  • Azoles: including fluconazole.
  • Antihistamines: particularly astemizole and mizolastine.
  • Discuss choice of antidepressant, covering:
  • anticipated adverse events – for example, side effects and discontinuation symptoms (see stopping or reducing antidepressants).
  • potential interactions with concomitant medication or physical illness2
  • Normally choose an SSRI in generic form. Take the following into account:
  • SSRIs are associated with an increased risk of bleeding. Consider prescribing a gastroprotective drug in older people who are taking NSAIDs or aspirin.
  • Fluoxetine, fluvoxamine and paroxetine have a higher propensity for drug interactions2.
  • For people who also have a chronic physical health problem, consider using citalopram or sertraline as these have a lower propensity for interactions.
  • Paroxetine is associated with a higher incidence of discontinuation symptoms.
  • Take into account toxicity in overdose for people at significant risk of suicide. Be aware that:
  • compared with other equally effective antidepressants recommended in primary care, venlafaxine is associated with a greater risk of death from overdose
  • the greatest risk in overdose is with TCAs, except for lofepramine.
  • When prescribing drugs other than SSRIs, take into account:
  • the increased likelihood of the person stopping treatment because of side effects, and the consequent need to increase the dose gradually, with venlafaxine, duloxetine and TCAs
  • the specific cautions, contraindications and monitoring requirements for some drugs2
  • that non-reversible MAOIs, such as phenelzine, combined antidepressants and lithium augmentation of antidepressants should normally be prescribed only by specialist mental health professionals (for more information see sequencing treatments).
  • that dosulepin should not be prescribed.
  • When prescribing antidepressants for older adults:
  • prescribe at an age-appropriate dose taking into account physical health and concomitant medication
  • monitor carefully for side effects.

(Cochrane 2008, CD 000448)

fluoxetine Amiodarone Dronedarone Quinidine Clarithromycin Erythromycin Fluconazole paroxetine venlafaxine Sertraline Citalopram Duloxetine phenelzine fluvoxamine dosulepin trazodone azithromycin Ampicillin Co-trimoxazole ciprofloxacin levofloxacin moxifloxacin sotalol haloperidol pimozide Methadone mefloquine chloroquine artemether lumefantrine astemizole mizolastine

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