Mebendazole Drug Interactions
Cimetidine is the most clinically significant drug interaction with mebendazole, as it inhibits mebendazole metabolism and increases plasma concentrations, requiring dose monitoring when co-administered. 1
Primary Drug Interaction: Cimetidine
- Cimetidine inhibits mebendazole metabolism, resulting in increased plasma concentrations and maximum concentration (Cmax) of mebendazole 1, 2
- This interaction occurs through inhibition of hepatic metabolism pathways 2
- Clinical management: Monitor for enhanced mebendazole effects and potential toxicity when these drugs are used together; consider alternative H2-blockers if possible 1
Anticonvulsant Interactions
- Enzyme-inducing anticonvulsants (phenytoin, carbamazepine, phenobarbital) decrease mebendazole exposure by increasing hepatic metabolism 2
- These interactions reduce the area under the plasma concentration-time curve (AUC) of mebendazole, potentially compromising efficacy 2
- Clinical management: Consider using higher doses of mebendazole or alternative anthelmintics in patients on chronic anticonvulsant therapy 2
Antiretroviral Interactions
- Ritonavir decreases the AUC of mebendazole through enzyme induction mechanisms 2
- This interaction may reduce mebendazole efficacy in HIV-infected patients requiring anthelmintic therapy 2
- Clinical management: Monitor treatment response closely and consider dose adjustments or alternative agents 2
Other Documented Interactions
Dexamethasone
- Increases albendazole (related benzimidazole) exposure but specific mebendazole interaction data is limited 2
- May theoretically affect mebendazole similarly given structural similarities 2
No Significant Interactions
- Ivermectin, azithromycin, diethylcarbamazine, praziquantel, and levamisole show no major pharmacokinetic interactions with mebendazole when co-administered 2
- These combinations can be safely used for polyparasitic infections 2
Hepatic Metabolism Considerations
- Mebendazole has poor systemic absorption, which limits the clinical significance of many potential drug interactions 3
- The drug's primary site of action is in the gastrointestinal tract, where it exerts its anthelmintic effects through microtubular destruction 3
- Prolonged therapy (>14-28 days) may increase risk of hepatotoxicity, particularly when combined with other hepatotoxic agents 4
Monitoring Recommendations
- Periodic assessment of hepatic function is advisable during prolonged mebendazole therapy, especially when combined with interacting medications 1
- No routine therapeutic drug monitoring is typically required for short-term anthelmintic courses 1
- Hematopoietic function monitoring should be considered during extended treatment periods 1
Special Populations
Pregnancy
- Mebendazole is Pregnancy Category C and has shown embryotoxic and teratogenic effects in rats at doses approximately equal to human doses 1
- Use is not recommended in pregnant women, particularly during the first trimester 1
- Drug interactions become particularly relevant when considering alternative agents in pregnant patients 1