Australasian Science: Australia's authority on science since 1938

New Life for Old Malaria Drug

Chloroquine could be given a new lease of life as an anti-malarial treatment simply by being administered differently.

The parasite that causes malaria has developed resistance to chloroquine, but research carried out at the Australian National University has shown that the parasite protein that causes resistance has an Achilles’ heel. “We studied diverse versions of this protein, and in all cases found that it is limited in its capacity to remove the drug from the parasite,” said Dr Rowena Martin. “This means malaria could once again be treated with chloroquine if it is administered twice-daily rather than just once a day.”

Martin and her colleagues also revealed how the protein may have developed resistance to chloroquine. “We found that the protein gains the ability to move chloroquine out of the parasite through one of two evolutionary pathways, but that this process is rigid – one wrong turn and the protein is rendered useless,” she said. “This indicates that the protein is under conflicting pressures, which is a weakness that could be exploited in future antimalarial strategies.”

Martin said the findings, published in the Proceedings of the National Academy of Sciences (USA), could be used to help millions of people in developing nations who are at risk of catching malaria. While chloroquine has been withdrawn from use in many developed countries, it is still used in developing nations in the South Pacific, Africa, Asia and South America.

Martin said that there is also potential to apply the findings to several chloroquine-like drugs that are also becoming less effective as the malaria parasite builds up resistance.

Martin does not recommend taking large doses of chloroquine. “The key is to increase the frequency of chloroquine administration, for example by taking a standard dose in the morning and another at night. If you take too much all at once it can kill you,” she cautions.