TdP). This risk is generally higher at elevated drugs concentrations of phenothiazines. Chlorpromazine is specifically associated with an established risk of QT prolongation and TdP; case reports have included patients receiving therapeutic doses of chlorpromazine. Agents that prolong the QT interval could lead to torsade de pointes when combined with a phenothiazine, and therefore are generally not recommended for combined use.
Cimetidine: Coadministration of dolasetron and cimetidine, a nonselective inhibitor of cytochrome P450, increased the blood concentrations of dolasetron's active metabolite by 24%.
Ciprofloxacin: Due to an increased risk for QT prolongation and torsade de pointes (TdP), caution is advised when administering dolasetron with ciprofloxacin. Ciprofloxacin has been associated with a possible risk for QT prolongation and TdP based on varying levels of documentation. Dolasetron has been associated with a dose-dependant prolongation in the QT, PR, and QRS intervals on an electrocardiogram. Dolasetron injection is contraindicated for use for the prevention of chemotherapy-induced nausea and vomiting because the risk of QT prolongation is higher with the doses used for this indication; when the injection is used at lower doses (i.e., those approved for post-operative nausea and vomiting) or when the oral formulation is used, the risk of QT prolongation is lower and caution is advised.
Cisapride: Dolasetron has been associated with a dose-dependant prolongation in the QT, PR, and QRS intervals on an electrocardiogram. Because of the potential for torsade de pointes (TdP), use of cisapride with dolasetron is contraindicated.
Citalopram: Due to a possible risk for QT prolongation and torsade de pointes (TdP), dolasetron and citalopram should be used together cautiously. Dolasetron has been associated with a dose-dependant prolongation in the QT, PR, and QRS intervals on an electrocardiogram. Use of dolasetron injection for the prevention of chemotherapy-induced nausea and vomiting is contraindicated because the risk of QT prolongation is higher with the doses required for this indication; when the injection is used at lower doses (i.e., those approved for post-operative nausea and vomiting) or when the oral formulation is used, the risk of QT prolongation is lower and caution is advised. Citalopram causes dose-dependent QT interval prolongation. According to the manufacturer, concurrent use of citalopram with other drugs that prolong the QT interval is not recommended. If concurrent therapy is considered essential, ECG monitoring is recommended.
Clarithromycin: Clarithromycin is associated with an established risk for QT prolongation and torsades de pointes (TdP). Clarithromycin should be used cautiously with other agents known to cause QT prolongation. Agents with potential to prolong the QT interval include: dolasetron.
Clobazam: A dosage reduction of CYP2D6 substrates, such as dolasetron, may be necessary during co-administration of clobazam. Limited in vivo data suggest that clobazam is an inhibitor of CYP2D6. If these agents are used in combination, it is advisable to monitor the patient for dolasetron-related adverse reactions.
Clomipramine: Tricyclic antidepressants should be used cautiously and with close monitoring with dolasetron. Dolasetron has been associated with a dose-dependant prolongation in the QT, PR, and QRS intervals on an electrocardiogram. Use of dolasetron injection for the prevention |
