Thesis suggests new alternative for malaria treatment in the Amazon

Publicação: 23 de February de 2015

According to the doctor in Tropical Diseases Andre Siqueira, the drug chloroquine is losing its effectiveness in a “worrisome” way in the Manaus area

Pros for drug association: lower daily drug ingestion, active substance have high effectiveness and the pediatric formulation

Pros for drug association: lower daily drug ingestion, active substance have high effectiveness and the pediatric formulation

The parasite known as Plasmodium vivax, the species that causes most malaria cases in the Amazon, has as its greatest enemy a drug called chloroquine, used for about 50 years in the Country against the disease. However, the effects of time show the drug is not as effective and there must have alternatives for the treatment. One of these possibilities was described in the PhD thesis by the infectious disease expert Dr. Andre Siqueira, under the supervision of Prof. Marcus Lacerda, who studied the treatment effects with the combination of artesunate and amodiaquine.

This drug combination (Coarsucam™/WintropR), result of a partnership between DNDi and Sanofi, is already successfully being used in African and Asian countries in the treatment against Plasmodium falciparum. “We had the opportunity to be the first group in the world to evaluate its use against malaria by Plasmodium vivax’, points Siqueira, Tropical Diseases PhD.

Among the pros of medicinal interaction – also known as ASAQ – regarding chloroquine is the smaller daily drug ingestion, besides the active substance presenting a high effectiveness. Another positive aspect is the availability of a pediatric formulation, what dismisses the need to fraction chloroquine pills for children at risk of inadequate administration and therapeutic flaw, as shown in an earlier paper.

Dr. Siqueira’s work, conducted in the Dr. Heitor Vieira Dourado Tropical Medicine Foundation, in Manaus, counted with 190 patients in each treatment branch, being accompanied for 42 days. During the first 28 days, no patients who received the ASAQ presented flaws. However, among those who received chloroquine, 7.6% presented flaws. This last drug presented even greater effectivity differences when considered the period until day 42, when this difference was of 22.6% (26.5% flaw in the chloroquine group versus 3.9% in the ASAQ).

“Our surprise was because chloroquine has a half-life considerably larger that amodiaquine, this is, the drug remains in the blood for a longer period, what would result, if the drug was effective, in greater protection”, explains the expert.

The difference in the cure rates, according to the expert, is due to the increase in the prevalence of Plasmodium vivax resistance to chloroquine in the research area. “Our study’s results – which’s team was highly active and involved, I must say – showed that chloroquine has been losing its effectiveness in a worrisome way in Manaus”, says.

Especially due to drug resistance, the physician suggests that alternatives should be actively evaluated and discussed in the Amazon. “The parasites evolve very rapidly, developing resistance. Replacing chloroquine, in my opinion, is a matter of time, demanding well-defined criteria for this shift, as well as choosing among the available drugs, the most adequate for our region”, explains.

The search for new drugs is needed especially because Plasmodium vivax is responsible for over 80% of the malaria cases in the Amazon. According to the annual report from the World Health Organization (WHO), released in December 2014, Brazil alone responds for 52% of all cases in the Americas, much ahead of Colombia (13%), the second country with most cases.…