SciDev.Net

[BEIJING] An old malaria drug that is cheap but increasingly ineffective could still play a role in the fight against the disease, according to research presented on 3 July at the 15th World Congress of Pharmacology in Beijing.

Chloroquine, previously one of the commonest anti-malaria drugs, is proving ineffective because malaria parasites are becoming resistant to it.

But according to Moshe Hoshen of the Braun Hebrew University-Hadassah in Israel, it could be combined with two drugs the World Health Organization (WHO) already recommends be used together to treat malaria.

Amodiaquine is similar to chloroquine and is used as a substitute for the older drug, while artesunate is the mostly widely used drug based on the plant extract artemisinin.

Artemisinin-based therapies are the newest generation of anti-malaria drugs, but there have been reports that malaria parasites are growing resistant to them (see 'Resistance is emerging' to antimalarial drug of choice).

Hoshen told SciDev.Net that in addition to the short supply of the plant from which artemisinin is extracted, its loss as an effective drug because of parasite resistance would mean that "many lives will be lost".

To limit the chance of resistance emerging, the WHO recommends combining artesunate with other drugs, mainly amodiaquine (see WHO warns against misuse of key malaria drug).

While the drugs work better in combination than singly, Hoshen says they still fail to treat malaria in about nine per cent of cases, especially in young children.

His research looked at factors such as the length of time a drug stays in the body, and where and how long it is active for.

He predicts that combining the three drugs would be much more effective than just using the amodiaquine-artesunate combination. He says that adding chloroquine, which costs just a few US cents per dose and has few side effects, could create "a radical cure".

Hoshen says the WHO should do clinical trials to test the effectiveness of the three drugs in combination.