The activity of combinations of currently used antigiardial drugs against Giardia duodenalis.

BACKGROUND

Drug-combination therapies are needed to combat treatment refractory giardiasis. However, data describing the activity of combinations of currently used drugs against Giardia duodenalis are unavailable.

METHODS

The in vitro activity of combinations of currently used antigiardial drugs were investigated against G. duodenalis.

RESULTS

Combinations of metronidazole with albendazole or quinacrine, and quinacrine with nitazoxanide, behaved additively, whereas combinations of metronidazole with nitazoxanide, albendazole or quinacrine behaved synergistically. Combinations of albendazole with nitazoxanide behaved antagonistically.

CONCLUSIONS

While combinations of metronidazole with nitazoxanide, or albendazole with quinacrine, may be effective treatments of giardiasis, combinations of albendazole with nitazoxanide are likely to result in negative pharmacodynamic interactions.