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Table 5 Top 20 QT drug-drug interaction (QT-DDI) along with their levels, therapeutic class and TdP risks of drugs involved in QT-DDIs

From: Frequency, characteristics and risk factors of QT interval prolonging drugs and drug-drug interactions in cancer patients: a multicenter study

QT-DDIs

Therapeutic class

TdP riska

Levels of QT-DDIsb

Frequency

Drug 1

Drug 2

Drug 1

Drug 2

Severity

Documentation

QT-DDIs: n (%)c

Ondansetron-Prochlorperazine

Antiemetic

Antipsychotic

Known risk of TdP

Not included in listsd

Major

Fair

88 (30.6)

Ciprofloxacin-Ondansetron

Antimicrobial

Antiemetic

Known risk of TdP

Known risk of TdP

Major

Fair

71 (24.7)

Ciprofloxacin-Prochlorperazine

Antimicrobial

Antipsychotic

Known risk of TdP

Not included in lists

Major

Fair

64 (22.2)

Ciprofloxacin-Metronidazole

Antimicrobial

Antimicrobial

Known risk of TdP

Conditional risk of TdP

Major

Fair

10 (3.5)

Ciprofloxacin-Dolasetron

Antimicrobial

Antiemetic

Known risk of TdP

Possible risk of TdP

Major

Fair

6 (2.1)

Dolasetron -Ondansetron

Antiemetic

Antiemetic

Possible risk of TdP

Known risk of TdP

Major

Fair

5 (1.7)

Dolasetron-Metronidazole

Antiemetic

Antimicrobial

Possible risk of TdP

Conditional risk of TdP

Major

Fair

5 (1.7)

Metronidazole-Ondansetron

Antimicrobial

Antiemetic

Conditional risk of TdP

Known risk of TdP

Major

Fair

4 (1.4)

Fluconazole-Metronidazole

Antimicrobial

Antimicrobial

Known risk of TdP

Conditional risk of TdP

Major

Fair

3 (1)

Prochlorperazine-Promethazine

Antipsychotic

Antiemetic

Not included in lists

Possible risk of TdP

Major

Fair

2 (0.7)

Ondansetron-Promethazine

Antiemetic

Antiemetic

Known risk of TdP

Conditional risk of TdP

Major

Fair

2 (0.7)

Metronidazole-Nilotinib

Antimicrobial

Kinase inhibitor

Conditional risk of TdP

Conditional risk of TdP

Major

Fair

2 (0.7)

Dolasetron-Octreotide

Antiemetic

Antidiarrheal

Possible risk of TdP

Not included in lists

Major

Fair

2 (0.7)

Clarithromycin-Ondansetron

Antimicrobial

Antiemetic

Known risk of TdP

Known risk of TdP

Major

Fair

2 (0.7)

Ciprofloxacin-Ketoconazole

Antimicrobial

Antimicrobial

Known risk of TdP

Conditional risk of TdP

Major

Fair

2 (0.7)

Ciprofloxacin-Fluconazole

Antimicrobial

Antimicrobial

Known risk of TdP

Known risk of TdP

Major

Fair

2 (0.7)

Prochlorperazine-Trimethoprim

Antipsychotic

Antimicrobial

Not included in lists

Not included in lists

Major

Fair

1 (0.3)

Prochlorperazine-Sulfamethoxazole

Antipsychotic

Antimicrobial

Not included in lists

Not included in lists

Major

Fair

1 (0.3)

Ondansetron-Tizanidine

Antiemetic

Muscle relaxant

Known risk of TdP

Not included in lists

Major

Fair

1 (0.3)

Nilotinib-Tizanidine

Kinase inhibitor

Muscle relaxant

Conditional risk of TdP

Not included in lists

Major

Fair

1 (0.3)

Metronidazole-Tizanidine

Antimicrobial

Muscle relaxant

Conditional risk of TdP

Not included in lists

Major

Fair

1 (0.3)

Metronidazole-Prochlorperazine

Antimicrobial

Antipsychotic

Conditional risk of TdP

Not included in lists

Major

Fair

1 (0.3)

Metronidazole-Norfloxacin

Antimicrobial

Antimicrobial

Conditional risk of TdP

Possible risk of TdP

Major

Fair

1 (0.3)

  1. AZCERT Arizona Center for Education and Research on Therapeutics, TdP torsades de pointes, QT DDIs QT prolonging drug-drug interactions
  2. aTdP risk was based on AZCERT QT drugs list
  3. bLevels i.e., severity and documentation were based on Micromedex DrugReax® classification
  4. cPercentage calculated in total number of QT-DDIs i.e., 288
  5. dDrugs involved in QT-DDIs were not included in the AZCERT QT drugs lists