Quality evaluation of chloroquine, quinine, sulfadoxine-pyrimethamine and proguanil formulations sold on the market in East Congo DR.

OBJECTIVE: Drug quality may be poor in many regions of the world. Our first aim was to verify whether the dose of the active compounds in various antimalarial medicines on the market in East Congo conforms to the quality requirements of the European Pharmacopoeia (Ph. Eur.). The second aim was to check the extent to which simple methods of analysis could be used to evaluate drug quality. METHODS: The formulations analysed included tablets, injections and syrups of chloroquine (CQ), quinine, sulfadoxine-pyrimethamine (SP) and proguanil. Ultraviolet (UV) spectrophotometry was used to quantify CQ and quinine in tablets and injections. Thin layer chromatography was used to identify the preservative(s) in the syrups. As the drug form (base or salt) in the tablets, is rarely declared, the estimated dose was calculated using both forms. High-performance liquid chromatography (HPLC) was used to check for assay interference and for measuring SP combinations. RESULTS AND DISCUSSION: When the dose declaration on the label was assumed to be of the salt form, 33% of CQ batches were underdosed and two of eight batches of quinine were underdosed by about 25% and 15% respectively. When the base form was assumed, only one batch of CQ tablets conformed. The underdosed batches contained about 50-66% of the claimed amount for CQ. The dose of quinine in the different batches of tablets was in the range 62-86%. For the CQ syrup, interference by the preservative Nipagin, confirmed by HPLC-UV, was observed with UV-spectrophotometry at 257 nm but not at 342 nm. The results for CQ syrup using UV-spectrophotometry at 342 nm and HPLC-UV at 257 nm were comparable and showed compliance with the European Pharmacopoeia limits of 95-105%. One of two batches of CQ injections and one of four batches of quinine injections were overdosed by about 14% and 8% respectively. The SP tablets were analysed by using HPLC-UV only. All five batches were underdosed in sulfadoxine (91-94%) but still met the United States Pharmacopeial (USP) limit of 90-110%. Two batches were slightly overdosed in pyrimethamine (106% and 108% respectively) while one batch contained neither active ingredient. The one batch of proguanil analysed, met the Ph. Eur. quality requirement (98.7%). CONCLUSION: Simple methods of analysis like UV-spectrophotometry can be used to check drug quality routinely. A substantial proportion of the antimalarial drugs sold on the Congo DR market is of poor quality. Some batches contain little or no drug. This is a serious threat to public health in the region of Congo DR.

Preparation of beta-artemether liposomes, their HPLC-UV evaluation and relevance for clearing recrudescent parasitaemia in Plasmodium chabaudi malaria-infected mice.

Egg phosphatidylcholine-cholesterol liposome formulations containing the antimalarial drug beta-artemether have been prepared and analyzed for their encapsulating capacity, chemical stability, leakage, in vitro release and their therapeutic efficiency against Plasmodium chabaudi infection. A HPLC-UV analysis of beta-artemether liposomes without derivatisation was achieved. A good linearity of y=4437.7 x+469.01 (R(2)=0.9999) with a detection limit of 2 microg ml(-1) was reached. Prior to this, liposomal formulations composed of different molar ratios of EPC-CHOL were prepared to select beta-artemether crystal-free liposome preparations. The formulation corresponding to 4:3 and a total concentration of 300 mg lipids ml(-1) buffer (pH 7.2), which could incorporate as much as 1.5 mg beta-artemether was selected for therapy. A trapping efficiency of nearly 100% was reached, the drug being located in the lipid bilayers. A dialysis test demonstrated that the drug could be reversibly released from the liposomes, reaching equilibrium within 24 h. After 3 months storage at 4 degrees C, no leakage of beta-artemether had occurred indicating a high stability of the liposomes. These liposomes were used to treat mice infected with the virulent rodent malaria parasite Plasmodium chabaudi chabaudi, with a 100% cure by clearing the recrudescent parasitaemia.

A comparison of the stage-specific efficacy of chloroquine, artemether and dioncophylline B against the rodent malaria parasite Plasmodium chabaudi chabaudi in vivo.

Chloroquine, artemether and dioncophylline B efficacy against Plasmodium chabaudi was compared. One intraperitoneal injection (10 mg/kg body weight) was given daily over 3 consecutive days to OF1 mice when they were predominantly bearing ring, trophozoite and schizont forms. The parasitaemia was monitored every 2 h during two schizogonic cycles and daily thereafter until parasites were cleared. Chloroquine was more efficient at the trophozoite stage, while artemether was effective against all erythrocytic stages, with a marked efficacy against the trophozoite stage. Chloroquine-treated and artemether-treated parasites displayed a pigment-clumping morphology and lowered the parasitaemia faster than dioncophylline B. Dioncophylline B was effective at trophozoite and schizont stages, but completely ineffective at the ring stage. These results demonstrate that a better timing of drug administration increases the efficacy of common and new antimalarial drugs and provides a model for antimalarial-action monitoring. Drug-induced changes in infected erythrocyte morphology are presented.

Differential sensitivity of erythrocytic stages of the rodent malaria parasite Plasmodium chabaudi chabaudi to dioncophylline B, a highly active naphthylisoquinoline alkaloid.

Four-week-old OF1 mice, infected with synchronized Plasmodium chabaudi chabaudi blood forms, were intraperitoneally injected with the naphthylisoquinoline alkaloid dioncophylline B (10 mg kg(-1) day(-1)) at three consecutive days. The respective groups were treated when rings, trophozoites, and schizonts were predominant. Microscopical observations of thin blood smears were made every two hours after the start of the experiment. A clear dependency of the effectiveness of dioncophylline B treatments on the timing of drug administration was demonstrated. Based upon the evolution of total parasitaemia and the survival rates, it was concluded that ring stages are insensitive to dioncophylline B, while the drug is highly effective when given at the trophozoite stage and partially effective when given at the schizont stage. Dioncophylline B seems to act by inhibiting the haemozoin degradation, as indicated by pigment clumping, and by impairing the segmentation of schizonts.

Chronobiology of Plasmodium chabaudi chabaudi: analysis of hourly recorded total and differential parasitaemia during a schizogonic cycle.

Detailed total and differential parasitaemia curves of asexual Plasmodium chabaudi chabaudi erythrocytic stages were recorded and analysed. Female, inbred, CBA/Ca mice were infected with the virulent IP-PC1 strain after in vitro synchronization of the parasites. Thin blood smears were made on an hourly basis, and the total and differential parasitaemia of ring forms, trophozoites and schizonts were counted after Giemsa staining. These curves reveal information that remains hidden when less detailed curves are examined: the duration and periodicity of the schizogonic cycle, the existence of a plateau, indications of a schizont withdrawal from the peripheral blood, the timing of the rise of the parasitaemia at each schizogony, and the invasion rate of the merozoites. In the perspective of developing a rational and efficient strategy for chronotherapy of malaria, such information should be taken into account.

Larvicidal activity of the naphthylisoquinoline alkaloid dioncophylline A against the malaria vector Anopheles stephensi.

The larvicidal activity of dionocophylline A, a naphthylisoquinoline alkaloid derived from the tropical vine Triphyophyllum peltatum (Dioncophyllaceae), was investigated against the malaria vector Anopheles stephensi. In direct and indirect inhibition assays it was demonstrated that the younger larval stages were very sensitive towards this natural product, with LC50 values below 1 mg/l. Pronounced effects were observed within 4 h of exposure. Aging larvae, however, were less sensitive, while pupae were totally insensitive to the action of dioncophylline A. The transformations from larvae to pupae and from pupae to adult mosquitoes remained unaffected. Therefore, dioncophylline A can be regarded as a promising specific larvicide.