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Suspect Moxifloxacin Induced Torsades de
Pointes: A case report
Ya-Wen
*
Yang ,
Hui-Hsiung Lai, Hui-Chuan Lin
Department of Pharmacy, Ditmanson Medical Foundation Chia-Yi Christian Hospital
Introduction
Discussion
Torsade de pointes (TdP) is a potentially lifethreatening
polymorphic ventricular tachyarrhythmia associated with
QT prolongation. Causes of TdP include congenital
prolonged QT interval syndromes and acquired
diseases, most commonly associated with drug therapy
and electrolyte abnormalities. Fluoroquinolones have
been reported to prolong the QTc interval and
precipitate TdP, but moxifloxacin-induced TdP is still
rare. We present a patient with major depressvie
disorder who developed TdP during moxifloxacin
therapy for pneumonia.
Case report
A 64-year-old female presented to the emergency
department complaining of general weakness and
chillness since that morning. Medical history included
major depressvie disorder, hypertension and cerebral
ischemic disease. Her routine medications were
shown at Fig 1. On arrival, T/P/R:38.8/108/18,
BP:151/84mmHg. Chest X-ray revealed bilateral
infiltrates. Laboratory data showed hyponatremia
(Na:116 mmol/L) and hypo-osmolarity (245 mosm/L).
Moxifloxacin 400 mg was initiated intravenously for the
empirical treatment of pneumonia. Approximately 5
hours later, sudden onset of conscious loss and
trismus was noted. EKG showed ventricular
tachycardia, then CPCR applied immediately. A
diagnosis of TdP was made. She regained
spontaneous circulation and was intubated with
mechanical ventilator support. Moxifloxacin was
discontinued and replaced with amoxicillin/clavulanic
acid. Normal saline challenge was also given to
correct hyponatremia. Her consciousness was fully
recovered and became hemodynamic stable. No
further episodes of TdP were noted.
Drug
Aripiprazole
Venlafaxine
Zolpidem
Lorazepam
Flunarizine
Fexofenadine
Famotidine
Dosage
7.5 mg HS
75 mg TID
10 mg HS
1 mg PRHS
10 mg QN
60 mg BID
20 mg BID
Fig. 1 Medication record of the patient
Start & Stop Date
Over 10 years
102, Mar till now
102, Mar till now
102, Mar to 104, Jul
104, Apr to June
104, Apr to June
104, Apr to June
Like all fluoroquinolones, moxifloxacin has the
potential to prolong the QTc interval, but TdP is very
rare. Risk factors of TdP include female sex, advanced
age, underlying heart disease, electrolyte imbalance,
concomitant drug use that prolongs the QTc interval,
severe bradycardia and presence of other diseases.
This patient didn’t have previous underlying heart
disease, in addition, hyponatremia may not contribute
to TdP. But several routine medications have been
associated with QTc interval prolongation, including
aripiprazole, venlafaxine and famotidine. Concurrent
use of these drugs may have additive effects on the
QT interval, although there were no episodes of TdP
noted before. Therefore, moxifloxacin was assumed to
be the predisposing factor for the development of TdP.
It also had a strong temporal relationship with the
occurrence of TdP. The use of the Naranjo adverse
drug reaction probability scale indicated a possible
relationship (score of 4) between the TdP observed
and moxifloxacin therapy in this patient.
Naranjo Algorithm for ADR Causality Assessment
Yes
No
1. Are there previous conclusive reports of this reaction?
2. Did the adverse event appear after the suspect drug was administered?
3. Did the adverse reaction improve when the drug was discontinued?
4. Did the adverse reaction reappear when the drug was readministered?
5. Are there alternate causes that could have caused the reaction?
6. Did the reaction appear when a placebo was given?
7. Was the drug detected in any body fluid in toxic concentrations?
8. Was the reaction more severe when the dose was increased or less
severe when decreased?
9. Did the patient have a similar reaction to the same or similar drugs in
any previous exposure?
10. Was the adverse event confirmed by any objective evidence?
+1
+2
+1
+2
-1
-1
+1
0
-1
0
-1
+2
+1
0
Don't
Know
0
0
0
0
0
0
0
+1
0
0
+1
+1
0
0
0
0
Total score =
Conclusion
The drugs that have the potential to prolong the
QTc interval must be used cautiously in patients with
multiple risk factors for TdP. Careful assessment of
the risk/benefit ratio is important before prescribing
these drugs.
Reference
1. N Engl J Med. 2004 Mar 4;350(10):1013-22
2. Cardiol J. 2008;15(1):71-3.
3. Am J Med Sci. 2009 Aug;338(2):164-6
Score
+1
+2
+1
0
-1
0
0
0
0
+1
4