The concentration of chloroquine in serum during short and long term malaria prophylaxis with standard and 'double' dosage in non-immunes: clinical implications.

The concentration of chloroquine in serum was analysed after one week, six weeks and one year on standard dose prophylaxis (300 mg chloroquine base once a week) and after six months on the double dose. After six weeks, the standard dose gave adequate protection against malaria. During the first weeks of prophylaxis insufficient protection might be achieved by the customary standard dose. In a double-dose group many values reached the point above which a higher incidence of side-reactions have been observed.