Prolongation of the QT interval observed in a Japanese patient with vivax malaria following treatment with halofantrine.

Abstract

In 1992, some 90 countries or territories where 42% of the world's population resided were considered malarious and estimation of deaths from malaria worldwide per year were in the order of 1.4 of 2.8 million. The higher the number of Japanese who go abroad becomes (the total number in 1994 was 13,578,934: Records of Statistical Division of the Ministry of Justice), the greater is the risk of their contracting malaria. Indeed, the reported annual number of imported malaria cases increased to not less than 100. Now, malaria should first be presumed if a patient complains of a higher fever after a visit to a tropical country. And the importance of instituting prompt diagnosis and proper treatment should also be stressed. One of the antimalarials which has been highlighted for its effectiveness is halofantrine. This drug has been used for treatment of human malaria since 1984, and to date clinical trials have involved about 3.4 million patients in more than 30 countries (personal communication). Several patients successfully treated with halofantrine without any treatment failure have also been documented in Japan. However, in 1993, a clinical study involving 400 patients on the Thai-Burmese border revealed cardiac effects of antimalarial treatment with halofantrine, including one sudden death after the treatment. There have also been some spontaneous reports of serious ventricular dysrythmiasis with prolongation of the QT intervals, rarely associated with death. The pharmaceutical company producing Halfan has reported 8 cardiac arrests, leading to 6 deaths, when a higher dose than recommended was used, there was recent or concomitant treatment with mefloquine, there was pre-existing prolongation of the QT interval or the patient had a thiamine deficiency. Finally, the World Health Organization (WHO) announced a "drug alert" on halofantrine advising a change in recommendations for its use. In the present paper, we discuss the first Japanese vivax malaria patient whose QT interval was prolonged after treatment with halofantrine.