Malaria in pregnant women and infants, and in preschool children where transmission is seasonal. There are a number of medications that can help prevent or interrupt malaria in travelers to places where infection is common. Many of these medications are also used in treatment. In places where "Plasmodium" is resistant to one or more medications, three medications—mefloquine, doxycycline , or the combination of atovaquone/proguanil ("Malarone")—are frequently used for prevention. Doxycycline and the atovaquone/proguanil are better tolerated while mefloquine is taken once a week. Areas of the world with chloroquine sensitive malaria are uncommon. The protective effect does not begin immediately, and
Mefloquine with an increased risk of birth defects or miscarriages. The drug may be used during breastfeeding, though it appears in breast milk in low concentrations. The World Health Organization gives approval for the use of mefloquine in the second and third trimesters of pregnancy and use in the first trimester does not mandate termination of pregnancy. Mefloquine is metabolized primarily through the liver. Its elimination in persons with impaired liver function may be prolonged, resulting in higher plasma levels and an increased risk of adverse reactions. The mean elimination plasma half-life of mefloquine is between two and four weeks. Total