chemoprophylaxis. Intramuscular injections or intravenous infu- sions of chloroquine hydrochloride can result in severe hypotension and respiratory and cardiac arrest, and should be avoided. Amodiaquine is closely related to chloroquine, and it probably shares mechanisms of action and resistance. Amodiaquine was widely used to treat malaria because of its low cost, limited toxicity, and, in some areas, effectiveness against chloroquine-resistant strains Chloroquine is contraindicated in patients with psoriasis or of P falciparum, but toxicities, including agranulocytosis, aplastic porphyria. It should generally not be used in those with retinal anemia, and hepatotoxicity, have limited its use. However, recent or visual field abnormalities or myopathy, and should be used reevaluation has shown that serious toxicity from amodiaquine is with caution in patients with liver, neurologic, or hematologic uncommon. The most important current use of amodiaquine is disorders. The antidiarrheal agent kaolin and calciumand in combination therapy. The World Health Organization (WHO) magnesium-containing antacids interfere with the absorption of lists artesunate plus amodiaquine as a recommended therapy for chloroquine and should not be co-administered. Chloroquine is falciparum malaria (Table 52–4). This combination is now available considered safe in pregnancy and for young children. as a single tablet (ASAQ, Arsucam, Coarsucam) and is the first-line
TABLE 52–4 WHO recommendations for the treatment of falciparum malaria.
Data from World Health Organization: Guidelines for the Treatment of Malaria, 3rd ed. World Health Organization. Geneva, 2015.
therapy for the treatment of uncomplicated falciparum malaria in many countries in Africa. Long-term chemoprophylaxis with amodiaquine is best avoided because of its apparent increased toxicity with long-term use, but short-term seasonal malaria chemoprevention with amodiaquine plus sulfadoxine-pyrimethamine (monthly treatment doses for 3–4 months during the transmission season) is now recommended by the WHO for the Sahel sub-region of Africa.
Piperaquine is a bisquinoline that was used widely to treat chloroquine-resistant falciparum malaria in China in the 1970s–1980s, but its use waned after resistance became widespread. More recently, piperaquine combined with dihydroartemisinin (Artekin, Duocotecxin) showed excellent efficacy and safety for the treatment of falciparum malaria, although very recently decreased efficacy has been seen in southeast Asia, linked to decreased activity of both components of the combination. Piperaquine has a longer half-life (~28 days) than amodiaquine (~14 days), mefloquine (~14 days), or lumefantrine (~4 days), leading to a longer period of post-treatment prophylaxis with dihydroartemisinin-piperaquine than with the other leading artemisinin-based combinations; this feature should be particularly advantageous in high-transmission areas. Dihydroartemisinin-piperaquine is now the first-line therapy for the treatment of uncomplicated falciparum malaria in some countries in Asia. As dihydroartemisinin-piperaquine offers extended protection against malaria, there is interest in chemoprevention with monthly dosing of the drug, which has shown excellent efficacy in children and pregnant women in Africa.