Combining two drugs into one might create treatments that can overcome resistance to antimalarial therapies.

The Plasmodium parasites that cause malaria are beginning to show resistance to drugs that have long been used to fight the disease, such as chloroquine. The drug artemisinin still works well in combination with other drugs, but health officials fear that use of this therapy by itself is promoting resistance to it.

Svetlana Tsogoeva at the Friedrich-Alexander University of Erlangen-Nuremberg in Germany and her colleagues combined existing antimalarial drugs to generate a series of 17 hybrid molecules. The researchers then tested the compounds on multidrug-resistant Plasmodium strains and on mice infected with malaria.

The hybrids were more likely than their individual components to kill resistant parasites, and they were more effective. One hybrid cured all of the mice on which it was tested; the same dose of one of its components cured only one-third.

The researchers suggest that hybrid treatments are more potent because cells take up the active parts of both drugs simultaneously.