Bioequivalence evaluation of a fixed combination of chloroquine and proguanil in a capsule formulation versus a standard medication.

To assess the bioequivalence between a test capsule with a fixed combination of chloroquine (CAS 54-05-7) and proguanil (CAS 500-92-5), and chloroquine and proguanil administered as separate tablets, an open two-sequence, two-period crossover randomized study was performed in twelve healthy volunteers who received a single oral dose of 100 mg chloroquine and 200 mg proguanil either in the form of one capsule or the reference tablets. Biological samples (plasma, whole blood and erythrocytes) were collected up to 43 days after drug administration. The parent drugs and their main metabolites were analyzed using high performance liquid chromatography assay. Bioequivalence was assessed for whole blood and plasma AUC and C max of chloroquine, proguanil, cycloguanil and 4-chlorophenylbiguanide. Bioequivalence in erythrocytes was also established except for C max of chloroquine. While the differences for C max of chloroquine in erythrocytes may be related to technical problems during the erythrocyte sampling procedure (contamination with leukocytes), bioequivalence can be concluded from the plasma concentration data. Therefore, the use of a single capsule instead of one chloroquine tablet and two proguanil tablets daily can be proposed in order to increase the prophylactic compliance without decreasing the prophylactic efficacy.