The effect of pentostam and cimetidine on the development of leishmaniasis (Leishmania mexicana amazonensis) and concomitant malaria (Plasmodium yoelii).

BALB/c mice were infected with Leishmania mexicana amazonensis and/or Plasmodium yoelii in order to determine the impact of multiple parasitic infection on the efficacy of chemotherapeutic agents. Uninfected, P. yoelii-infected, L.m. amazonensis-infected, and L.m. amazonensis and P. yoelii-infected mice were inoculated with cimetidine (80 mg kg-1 day-1) or pentostam (200 mg kg-1 day-1) once a day for an initial 20-day period, and once a week thereafter. Leishmania mexicana amazonensis lesion development and P. yoelii parasitaemia were the criteria used to assay disease severity. Mice infected with both P. yoelii and L.m. amazonensis developed more severe disease than did animals infected with either parasite alone. Cimetidine and pentostam each slowed the development of L.m. amazonensis in animals infected with only that parasite and in animals infected with both P. yoelli and L.m. amazonensis. However, mice treated with pentostam developed more severe P. yoelii infections than did control animals, whereas cimetidine significantly reduced P. yoelii parasitaemia in all instances.