Pharmacokinetics/Pharmacodynamics findings after repeated administration of ARTESUNATE thermostable suppositories (RECTOCAPS) in Vietnamese patients with uncomplicated malaria.

In recent years, Artemisinin and particularly one of its derivatives--Artesunate (ART--has become an essential alternative for treatment of both uncomplicated and severe falciparum malaria in Asia and Africa as well. Therefore, these compounds are still and inccreasingly in the focus of interest because of quick acting of this drug, is able to help even unconscious to overcome the malaria attack, when administered by injection. As an alternative, RECTOCAPS have been developed and their use is meanwhile well established. From earlier studies in children, suffering from plasmodium falciparum malaria, we obtained a high level of DHART in the blood, but as expected also a rapid decline in the levels of both DHART and ART. A second administration of ART was additionally applied 4 hours after the first administration. DHART and ART plasma levels were found to last longer on an assumed therapeutic level than those obtained after one administration only. The fever clearance and the parasitemia reduction rates were found to be effective according to this dosing regimen. In view of these findings, we decided to conduct the actual described study by administering 200 mg of ART every 3 hours (0, 3, 6 and 9 h) by the rectal route. Soft geiatine capsules (RECTOCAPS) containing 200 mg of ART GMP--type each (Artesunic acid) were administered by rectal route. Each patient received four RECTOCAPS capsules (4 x 200 mg of ART) over a 3 h period. 12 adult patients with uncomplicated malaria were selected. Age, weight, height, body temperature, parasite counts before treatment and their evolution until 96 h are determined. Blood samples were taken at short time intervals after starting with the first medication: 0, 30 min, 60 min, 3 h, 6 h, 9 h, 12 h, 24 h, 36 h, 48 h, 60 h, 72 h, 84 h, 96 h and 108 h. The aliquots of all the blood samples were used for performing parasite counts. Plasma obtained following the traditional procedure was kept at -40 degrees C until analysis. HPLC technique with electrochemical detector was used for quantification of ART and DHART. From the blood concentration values of ART and DHART, the following observation can be derived: the onset of action is observed within the first half hours, therapeutic levels of the drug obtained (89 microg/ml ART compared to 84 microg/ml DHART). The DHART levels are somewhat higher than those of ART (a peak concentration after 6 h starting medication of 151 microg/ml ART as compared to 276 microg/ml DHART). The variations as a function of frequency of DHART uptake are much less marked than those observed for ART. Another finding is that after the administration, some sort of a plateau of DHART and ART is built up, lasting at least from 9 to 12 hours with DHART level of about 190 microg/ml and ART of 90 microg/ml. In the case of single-dose administration, the levels of both compounds were below the detection threshold after three hours. With regard to the parasite counts, although there were inter-individual variations, it should be noted that after 48 hours a high proportion of the patients (8 out of 12) was completely clear of parasites. Similar results were observed with regard to the body temperature (7 out of 12 returned to normal temperature 36 hours after starting the therapy). The findings of the study support the RECTOCAPS application principle resulting in effectiveness both for the velocity of drug uptake as well as for the height of plasma levels. Repeated administration of ART can extend the duration of therapeutic plasma levels of the drug.

[Chemosusceptibility analysis of Plasmodium falciparum imported from Comoros to Marseilles, France in 2001-2003]. / Chimiosensibilité de Plasmodium falciparum importé des Comores à Marseille en 2002-2003.

OBJECTIVES: The aim of this work was to study the chemosensitivity of Plasmodium falciparum strains isolated from patients presenting with malaria after having returned from Comoros Islands in 2002-2003, and hospitalized at the North University Hospital, in Marseilles, France. MATERIALS AND METHODS: In vitro drug susceptibility (for strains maintained in culture) and mutation-specific polymerase chain reaction (PCR) assays (for all strains) were performed. RESULTS: Out of 23 strains kept in culture, 50% were shown to be resistant in vitro to chloroquine, 50% were resistant to pyrimethamine, 40% to cycloguanil, 25% to atovaquone, and 7% to mefloquine. However all these strains were susceptible to quinine, halofantrine, and artemether. Moreover, 48 strains were tested by molecular methods. As a result, 69% were shown to have the Asp108 mutation in the dihydrofolate reductase gene (Pfdhfr), the basic mutation associated with antifolate resistance, and 54% had additional mutations Ile51 plus Arg59, associated with a high level of resistance. Furthermore, 90% of the 20 strains tested in 2003 were shown to have the point mutation Pfcrt76 in the P. falciparum chloroquine resistance transporter (Pfcrt) gene recently proposed as a molecular marker of chloroquine-resistance. CONCLUSION: Obtaining plasmodium strains from Comoros to be tested in Marseilles, where all laboratory facilities are available, is a unique opportunity to establish a surveillance of falciparum drug resistance in the Comoros islands.

[Malaria in military personnel: the case of the Ivory Coast in 2002-2003]. / Le paludisme vu des tranchées: le cas de la Côte d'Ivoire en 2002-2003.

French troops were sent to the Ivory Coast on September 22, 2002 within the framework of Operation Unicorn in response to the political unrest. From September 22 to October 20, a total of 37 cases of malaria were reported, i.e., 35.7 cases per 1000 man-months. As of October 11, the central headquarters of the Armed Services Health Corps decided to use doxycycline as the exclusive agent for drug prophylaxis in military personnel on duty in the Ivory Coast and to enhance vector control measures. The incidence of malaria decreased to 2 cases per 1000 man-months at the sixth month. A recrudescence of malaria to 15 cases per 1000 man-months was observed with the rainy season in April. During this period one person presenting severe malaria with coma required emergency evacuation to France. In May 2003, several studies were undertaken to determine the factors that caused this recrudescence. These studies included surveys to evaluate awareness concerning malaria and monitor compliance with drug prophylaxis and tolerance of doxycycline, a case-control study to identify factors related to malarious episodes and an entomological study. Awareness of malaria was high with 75% of the 477 respondents stating that malaria could be transmitted by single mosquito bite. The case-control study showed a correlation between occurrence of malarious bouts and non-compliance with drug prophylaxis (p < 10(-5)). The odds-ratio was 3.05 (95% confidence interval, 1.52-6.14) for subjects claiming zero to one incident of non-compliance per week and 7.51 (IC95%, 3.24-17.40) for those claiming more than one incident of non-compliance per week. Tolerance of doxycyline was good since 72% of respondents reported no adverse effects. The main vector was Anopheles gambiae. The number of bites per man per night ranged from 25 to 2 and the number of infected bites ranged from 2 to 3 per week. Treatment was initiated promptly using quinine at a total dose of 25 mg/kg in 3 daily doses for 7 days by the intravenous then oral route. This experience shows that malaria remains a major concern for military forces, that standardization of preventive measures in emergency situations is needed, and that enhanced vector control, verification of compliance with drug prophylaxis and prompt treatment based on the presence of a physician in each emergency outpost is crucial. These recommendation must be applied to all French military personnel in the Ivory Coast.

[Imported malaria in 2000 in 2 northern Paris hospitals]. / Le paludisme d'importation en 2000 dans deux hôpitaux du nord de la région parisienne.

The number of travellers in malaria striken areas increases each year (2). The risk of infection is high in Sub-Saharan Africa, but appropriate chemoprophylaxis can reduce the morbidity and mortality rate of malaria. Half of the samples of malaria cases received by the National reference centre of malaria chemosensibility (CNRCP) for chemosensibility analysis came from two hospitals in the north of Paris: Bichat Claude Bernard in Paris and Delafontaine in Saint-Denis. In 2000, quite all the malaria cases (n = 387) observed at the Bichat and Delafontaine Hospitals came from Africa (99%). Plasmodium falciparum remains the most represented (87.6%) species, with an average parasitic density of 0.3%. Patients with P falciparum came for medical advice on the tenth day after return (median, extremes 0-174 days). More than half of the patients (58%) did not take any medication for chemoprophylaxis and even if they took some, it was irregular or inappropriate. The most used drug chemoprophylaxis is the association of chloroquine and proguanil or Savarine. In 15% of the cases, the travellers took chloroquine as a prophylaxis and 4% other medicine not recommended by the French authorities. An average of 43.7% of these travellers took inappropriate chemoprophylaxis. In total, 27 chemoprophylaxis failures are reported. Some patients (22%) have already taken self treatment which was readjusted during admission at hospital. The first treatment of malaria in 2000 was monotherapy with quinine (P. falciparum) and chloroquine (P. ovale, malariae, vivax). The treatment associations in case of suspicious resistance were quinine + doxycycline and atovaquone + proguanil. Treatment failure was infrequent and resulted above all from a bad observance. More information should be given to travellers as well as doctors about recommendations and treatments.

Inland valley rice production systems and malaria infection and disease in the savannah of Côte d'Ivoire.

In sub-Saharan Africa, lowlands developed for rice cultivation favour the development of Anopheles gambiae s. l. populations. However, the epidemiological impact is not clearly determined. The importance of malaria was compared in terms of prevalence and parasite density of infections as well as in terms of disease incidence between three agroecosystems: (i) uncultivated lowlands, 'R0', (ii) lowlands with one annual rice cultivation in the rainy season, 'R1' and (iii) developed lowlands with two annual rice cultivation cycles, 'R2'. We clinically monitored 2000 people of all age groups, selected randomly in each agroecosystem, for 40 days (in eight periods of five consecutive days scheduled every 6 weeks for 1 year). During each survey, a systematic blood sample was taken from every sick and asymptomatic person. The three agroecosystems presented a high endemic situation with a malaria transmission rate of 139-158 infective bites per person per year. The age-standardized annual malaria incidence reached 0.9 malaria episodes per person in R0, 0.6 in R1 and 0.8 in R2. Children from 0 to 9-year-old in R0 and R2 had two malarial attacks annually, but this was less in R1 (1.4 malaria episodes per child per year). Malaria incidence varied with season and agroecosystem. In parallel with transmission, a high malaria risk occurs temporarily at the beginning of the dry season in R2, but not in R0 and R1. Development of areas for rice cultivation does not modify the annual incidence of malarial attacks despite their seasonal influence on malaria risk. However, the lower malaria morbidity rate in R1 could be explained by socio-economic and cultural factors.

[Franco-Vietnamese military cooperation in the field of malaria]. / La cooperation militaire Franco-Vietnamienne dans le domaine du paludisme.

In 1991 after the long period of strife the international community moved on deploying a program for malaria control in Vietnam. At that time epidemiological surveys documented one million cases a year including 4 to 5,000 fatalities. This was the starting point for a military and defense cooperation program between the Vietnamese Army Health Corps and the Tropical Medicine Institute of the French Army Health Corps (French acronym, IMTSSA). The IMTSSA has the full range of expertise to train therapists, epidemiologists and research workers as well as to perform detection and pharmacological study of drug-resistant malaria strains. Between 1996 and 2002, the IMTSSA sent various specialists to Vietnam within the framework of this program. These specialists have not only established state-of-the-art technical facilities for epidemiological surveys and biological research but also trained Vietnamese specialists to perform these duties. This program has contributed to controlling malaria in Vietnam. Further development is needed to coordinate the exchange of data necessary to continuously monitor the efficacy of control measures in Southeast Asia where the incidence of strains resistant to most currently used antimalarials has been increasing sharply.

Profile and evolution of the chemosusceptibility of falciparum malaria imported into France in 2000.

In 2000, the chemosusceptibility of imported malaria was stable in France. All countries of infection considered, the bi-resistance to chloroquine and cycloguanil has not changed from 1996 to 2000. The monotherapy using quinine or mefloquine remains the first-line treatment to falciparum malaria. Resistance to these two antimalarials is rare in Africa and has not evolved over the past 15 years.

[Antimalarial chemoprophylaxis in the French army: development from 1986 to 2001]. / La chimioprophylaxie antipaludique dans les armées françaises: évolution de 1986 à 2001.

In 1999, almost 25,000 French soldiers were deployed in malaria transmission areas. With an incidence of 4.5 p. 100 men.year, malaria infection remains a serious problem requiring priority status for control in military personnel. Epidemiological surveillance provides data necessary to assess morbidity due to malaria, monitor changing patterns of Plasmodium falciparum drug-sensitivity, and evaluate the efficacy of malaria control measures. In 1990, the French army replaced chemoprophylaxis using chloroquine alone with combination treatment using a single capsule containing 100 mg of chloroquine base and 200 mg of proguanil chlorhydrate. This measure in association with the use deltamethrine impregnated bed-nets led to a significant decrease in incidence. However a comeback was observed from 1993 to 1997. Since 1995, the effectiveness of the chloroquine-proguanil combination has diminished mainly in the stable malaria areas. In response to increasing Plasmodium falciparum resistance to chloroquine-proguanil chemoprophylaxis, it was necessary to find an alternative. Two studies carried out among French soldiers in Sub-Saharian Africa between 1996 and 1998 demonstrated that a daily dose 100 mg doxycycline was more effective than the chloroquine-proguanil combination. In addition the 1998 study showed that doxycycline monohydrate in the form of a multiparticle tablet was better tolerated. In 2001 four drugs are used for malaria chemoprophylaxis in the army personnel, i.e., chloroquine and proguanil in combination, mefloquine, and doxycycline, depending on location and duration of mission. The chloroquine-proguanil combination is used in countries with chloroquine-resistant strains, e.g., Chad and Senegal. Mefloquine and doxycycline are used in countries with chloroquine-resistant strains. Due to increasing resistance, it will be necessary to evaluate other drugs or antipaludian combinations.

Cardiac effects of amodiaquine and sulfadoxine-pyrimethamine in malaria-infected African patients.

The cardiac effect of amodiaquine and sulfadoxine-pyrimethamine was studied in adult Cameroonian patients with acute uncomplicated Plasmodium falciparum malaria by electrocardiographic monitoring over the course of 7 days. Clinical and parasitological responses were monitored until Day 14. Bradycardia was observed in 16 of 20 amodiaquine-treated patients on Day 2, which corresponds to the time when maximal cumulative plasma concentration is reached, and in 12 of 20 patients on Day 7. A bradycardic effect lasting several days was not noted in patients treated with sulfadoxine-pyrimethamine. Significantly prolonged P, PQ, QRS, and QTc intervals were recorded on Day 2 after both 30 and 35 mg of amodiaquine base per kilogram of body weight had been administered, but these intervals were not correlated with the plasma monodesethylamodiaquine (main human active metabolite of amodiaquine) level. Electrocardiographic changes after therapy with sulfadoxine-pyrimethamine were minor and transient. All patients had fever and parasite clearance on or before Day 3 and remained free of fever and parasites until Day 14. None of the patients complained of cardiovascular adverse effects during the follow-up. These results suggest the absence of significant cardiac effects of amodiaquine and sulfadoxine-pyrimethamine at usual therapeutic doses, but they should draw the attention of clinicians treating malaria-infected patients who have taken other antimalarial drugs with cardiovascular side effects or those who are under treatment with cardiovascular drugs.

[Prevention and treatment of malaria: in vitro evaluation of new compounds]. / Prophylaxie et traitement du paludisme: évaluation in vitro de nouveaux composés.

One of the current options for reducing the morbidity and mortality of malaria are chemoprophylaxis and chemotherapy. For this reason, the increasing prevalence of strains of Plasmodium falciparum resistant to chloroquine and other antimalarial drugs poses a serious problem for control of malaria. There is an urgent need to find and develop novel compounds and to identify novel chemotherapeutic targets. Different approaches to discover new compounds are presented from examples of molecules studied in the Tropical Medicine Institute of the French Army Health Service (IMTSSA) evaluation against isolates of compounds in pharmaceutical development in collaboration with pharmaceuticals (pyronaridine, benflumetol, ferrochloroquine), screening of molecules which are still registered for other pathologies (antibiotics), screening of new synthesized compounds (artemisinin derivatives) and identification of parasitical targets and essential metabolic ways for parasite, and identification of molecules acting on these targets (reversal of resistance to chloroquine, iron chelators).

Chemoresistance of P. falciparum in urban areas of Yaounde, Cameroon. Part 1: Surveillance of in vitro and in vivo resistance of Plasmodium falciparum to chloroquine from 1994 to 1999 in Yaounde, Cameroon. / Chimiorésistance de P. falciparum en milieu urbain à Yaoundé, Cameroun. Part 1: S urveillance in vitro et in vivo de la résistance de Plasmodium falciparum à la chloroquine entre 1994 et 1999 à Yaoundé, Cameroun.

Chloroquine is indicated for the first-line treatment of uncomplicated malaria in most African countries. However, the spread of chloroquine-resistant Plasmodium falciparum requires periodic monitoring. Between 1994 and 1999, we studied the evolution of chloroquine resistance in adults (aged > 15 years) and children aged 5-15 years by using tests of therapeutic efficacy and in vitro assays. Responses to the 14-day in vivo test were classified according to the new criteria established by the World Health Organization. The results of the semi-microtest and the microtest were expressed as the 50% inhibitory concentration (IC50), and the threshold level of resistance was set at IC50 > 100 nM. The overall percentages of clinical and parasitological failures were 39.7% (31. 3% - 48.1%) and 48.8% (40.2% - 57.4%), respectively. Similarly, the percentage of isolates that were resistant in vitro was 52.5%. During the study, IC50 geometric mean varied between 84,6 nM and 149, 8 nM. The results of the in vitro assays agreed with those of tests of therapeutic efficacy (kappa coefficient = 0.69). The patients' chloroquine plasma levels were measured on day 0, day 3, day 7, and day 14. Drug measurement showed wide inter-individual variations and higher plasma levels in adults than in children. Some cases of therapeutic failure were associated with inadequate plasma levels of chloroquine. Our results confirm the high level of chloroquine resistance in Yaoundé and suggest that the use of an alternative antimalarial drug for the first-line treatment of uncomplicated malaria is warranted.

Chemoresistance of Plasmodium falciparum in the urban region of Yaounde, Cameroon. Part 2: Evaluation of the efficacy of amodiaquine and sulfadoxine-pyrimethamine combination in the treatment of uncomplicated Plasmodium falciparum malaria in Yaounde, Cameroon. / Chimiorésistance de P. falciparum En milieu urbain à Yaoundé, Cameroun. Part 2: evaluation de l'efficacité de l'amodiaquine et de l'association sulfadoxine-pyriméthamine pour le traitement de l'accès palustre simple à Plasmodium falciparum à Yaoundé, Cameroun.

The spread of chloroquine resistance or its stabilization at a high level calls for a change in the therapeutic strategy, including a possible replacement of chloroquine. We assessed and compared the efficacy of amodiaquine and sulfadoxine-pyrimethamine in Yaoundé. Of 140 adults and children > 5 years enrolled in the study, 59 in the amodiaquine and 58 in the sulfadoxine-pyrimethamine treatment group were followed until day 14. The efficacy of amodiaquine was 100%, whereas 12.1% of the patients treated with sulfadoxine-pyrimethamine responded with an early treatment failure. Side effects in both treatment groups were mild and did not require any specific treatment. We did in vitro drug assays for monodesethylamodiaquine (active metabolite of amodiaquine) and pyrimethamine and measured plasma levels of monodesethylamodiaquine, sulfadoxine, and pyrimethamine. Unlike amodiaquine, the results of the in vitro drug sensitivity test for pyrimethamine were not concordant with the clinical response. A wide inter-individual variation in the plasma drug levels was observed. Unlike chloroquine, the mean plasma concentrations did not vary with age. There was no significant difference in the plasma concentrations of sulfadoxine and pyrimethamine between patients responding with an adequate clinical response and those responding with treatment failure. Amodiaquine has several advantages over sulfadoxine-pyrimethamine combination and may be considered to be an effective drug in an endemic zone with a moderate level of chloroquine resistance.

Sequence variations in the genes encoding dihydropteroate synthase and dihydrofolate reductase and clinical response to sulfadoxine-pyrimethamine in patients with acute uncomplicated falciparum malaria.

Mutations in dihydropteroate synthase (DHPS) and dihydrofolate reductase (DHFR) are associated with in vitro resistance to sulfadoxine and pyrimethamine, respectively. The response of 75 patients to sulfadoxine-pyrimethamine was determined, and the genes of the corresponding Plasmodium falciparum isolates were sequenced. Of 12 different unmixed allelic combinations, the triple dhfr mutation Asn-108/Arg-59/Ile-51 was observed in all patients responding with early treatment failure. Some, but not all, patients with an adequate clinical response also harbored isolates with the triple dhfr mutation. Higher initial parasitemia and fever distinguished these 2 patient groups. The dhps genotype apparently had no influence on the clinical outcome. The other dhfr alleles with 1 or 2 mutations and the wild-type allele were found in patients with an adequate clinical response. The triple dhfr mutation is one of the genetic determinants associated with in vivo resistance to sulfadoxine-pyrimethamine.

[In vitro sensitivity of Plasmodium falciparum isolates from Gabon to chloroquine and cycloguanil]. / Sensibilité in vitro d'isolats gabonais de Plasmodium falciparum vis-à-vis de la chloroquine et du cycloguanil.

The in vitro susceptibility of 91 Plasmodium falciparum isolates obtained from malaria-infected children living near Libreville (Gabon) was evaluated against chloroquine and cycloguanil (biologically active metabolite of proguanil), using an isotopic micro-drug susceptibility test. In vitro resistance to chloroquine and cycloguanil was observed in 83% (35/42) and in 38% (30/78) of the patients, respectively. Our data showed that 41% (16/39) of Gabonese field isolates were resistant both to chloroquine and cycloguanil. These findings are of great importance because they might indicate imminent chloroquine-proguanil failure, and there are not many affordable antimalarial drugs to replace chloroquine-proguanil combination.