Chloroquine in malaria. Isn't it time for revision of prophylaxis schedules?

Two antimalarial prophylactic regimens were compared in healthy subjects belonging to the flying personnel of Scandinavian Airlines System. Regimen I: 310 mg chloroquine (CQ) base was given once weekly, starting the week prior to departure to the endemic area, then weekly during presence there and for four weeks after return. Regimen II: a loading dose of 620 mg chloroquine base was given at the latest 48 h prior to departure to the endemic area, followed by 310 mg base weekly throughout the visit. Blood samples were analysed by HPLC for CQ and its major metabolite desethylchloroquine (CQM). Regimen I gave suboptimal whole blood concentrations of CQ and CQM at the end of the first week of treatment. Regimen II gave prophylactic concentrations from the beginning of visit up to 6 weeks after departure from the endemic area. Both regimens were well tolerated, but Regimen II appeared better accepted by the volunteers due to its shorter duration.