4. Drug-Drug Interactions
Patient profiles will be reviewed to identify those drug regimens, which may result in clinically significant drug-drug interactions. The following drug-drug interactions summarized in Table 4 are considered clinically relevant for serotonin 5-HT3 receptor antagonists. Only those drug-drug interactions classified as clinical significance level 1 or those considered life-threatening which have not yet been classified will be reviewed.
| Target Drug | Interacting Drug | Interaction | Recommendation | Clinical Significance Level* |
|---|---|---|---|---|
| dolasetron, granisetron, ondansetron, palonosetron | QTc interval-prolonging medications (e.g., class Ia anti-arrhythmic agents†, class III anti-arrhythmic agents††, erythromycin, gemifloxacin, ziprasidone, tricyclic antidepressants, phenothiazines, pimozide) | increased risk of cardiotoxicity (QTc prolongation, torsades de pointes, cardiac arrest) due to potential for additive QT interval prolongation | monitor for interaction; alternative drug therapy may be preferred | contraindicated, major (DrugReax) 1-severe, 2-major (CP) |
| dolasetron, granisetron, ondansetron, palonosetron | apomorphine | potential for profound hypotension and loss of consciousness due to additive hypotensive effects | avoid concurrent use | contraindicated (DrugReax) 1-severe (CP) |
| dolasetron, granisetron, ondansetron, palonosetron | serotonergic agents | potential for serotonin syndrome with combined therapy due to additive serotonergic effects | monitor for signs/ symptoms of serotonin syndrome (e.g., hyperthermia, hypertension, rigidity) and discontinue combined therapy, if symptoms present | major (DrugReax) 2-major (CP) |
Legend:
- † Class Ia anti-arrhythmic agents include quinidine, disopyramide, procainamide
- †† Class III anti-arrhythmic agents include amiodarone, sotalol, dofetilide
- * CP = Clinical Pharmacology