Two anti-malaria drugs have fewer side effects

NEW YORK (Reuters Health) - Two drugs used to prevent malaria in travelers appear to have a lower risk of side effects than a third commonly prescribed medication, according to a research review published Tuesday.

The review looked at eight clinical trials of various anti-malaria drugs -- including mefloquine, atovaquone-proguanil and the antibiotic doxycycline. All three are considered drugs of choice for travelers heading to most malaria-endemic regions.

However, the study found, both atovaquone-proguanil -- sold under the brand-name Malarone -- and doxycycline appear to have fewer side effects.

With these two drugs, there is lower risk of nausea, stomach pain and other gastrointestinal side effects, and also neurological and psychiatric side effects, such as dizziness, sleep disturbances, anxiety and depression.

There were no severe side effects -- problems that were life-threatening or required hospitalization -- in any of the studies.

The investigators did, however, find published case reports linking mefloquine to 22 deaths, including five suicides. No other anti-malaria drugs have been linked to deaths when taken at prescribed doses, the researchers note in their review, published in the Cochrane Library, a publication of the Cochrane Collaboration, an international organization that evaluates medical research.

Despite the higher risk of side effects with mefloquine, the findings do not necessarily mean that travelers should avoid this drug, according to the researchers.

Doctors prescribe anti-malaria medications based on a number of factors -- including which country travelers are visiting -- and mefloquine may still be appropriate, particularly for people who have taken it before without problems.

"The main message is that you have to take some malaria chemoprophylaxis (preventive treatment) if you go to an endemic area," lead researcher Dr. Frederique Jacquerioz, of Tulane University in New Orleans, noted in a written statement. "It's one of the best preventive measures we have."

Caused by a mosquito-borne parasite, malaria is endemic in large areas of Africa, Asia and South and Central America, where it kills about 1 million people a year.

An estimated 10,000 to 30,000 travelers develop malaria every year, of whom about 150 die.

Across the eight studies in the current review, there was no evidence that mefloquine, Malarone and doxycycline differed in their effectiveness.

When it came to side effects, however, Malarone was about half as likely as mefloquine to cause gastrointestinal side effects, and 14 percent to 50 percent less likely to have a neurological or psychiatric side effect.

In one study, 69 of 493 Malarone users developed some type of neuropsychiatric side effect -- including dizziness, insomnia or strange dreams. That compared with 139 of 483 mefloquine users.

Similarly, doxycycline users had a 16 percent lower risk of neurological or psychiatric symptoms.

Still, severe reactions to mefloquine are rare, noted Dr. Andrea Boggild of Toronto General Hospital in Canada, who was not involved in the study. In a written statement, Boggild said that severe neurological and psychiatric symptoms develop in just one out of every 6,000 to 10,000 people who take the drug.

Boggild advised people who are planning a trip to a malaria-endemic area to talk with a healthcare provider who specializes in travel medicine about how to best protect themselves.

SOURCE: Cochrane Library, online October 7, 2009.