Single dose artemisinin-mefloquine versus mefloquine alone for uncomplicated falciparum malaria

Artemisinin reduces acute ovarian ischemia-reperfusion injury in rats

Artemisinin (ARS) is well known as an effective agent in the treatment of malaria through the rapid elimination of Plasmodium falciparum parasites. This study aims to investigate the effect of ARS in treating adnexal torsion, one of the most common gynecological surgical emergencies. ARS was administered intraperitoneally once 30 min before unilateral ovarian torsion in two different doses (10 mg/kg vs. 50 mg/kg). Torsion was maintained for 3 h and then held in the detorted state for 3 h. Bilateral adnexectomy was performed to measure antioxidant enzyme activities and oxidant levels on the ipsilateral ovary and to make histopathological and immunohistochemical analyses on the contralateral ovary. Ischemia-reperfusion (I/R) injury dramatically upregulated the activities of CAT, GST, and MDA levels in the ipsilateral ovary, which were all downregulated by ARS treatment. A significant increase in follicular cell degeneration, congestion, and edema in the contralateral ovary was seen in the I/R group, which was significantly reduced with ARS treatment. Furthermore, I/R injury resulted in a significant increase in apoptosis as shown by the increased levels of BAX and CASP-3, and decreased levels of BCL-2 whereas ARS significantly reduced the impact of the injury. Our data, based on a rat I/R injury model, show that both ipsilateral and contralateral ovaries are protected with ARS pretreatment, and 50 mg/kg ARS treatment demonstrates to be more effective than the 10 mg/kg ARS.

More insights into the pharmacological effects of artemisinin

Artemisinin is one of the most widely prescribed drugs against malaria and has recently received increased attention because of its other potential biological effects. The aim of this review is to summarize recent discoveries of the pharmaceutical effects of artemisinin in basic science along with its mechanistic action, as well as the intriguing results of recent clinical studies, with a focus on its antitumor activity. Scientific evidence indicates that artemisinin exerts its biological activity by generating reactive oxygen species that damage the DNA, mitochondrial depolarization, and cell death. In the present article review, scientific evidence suggests that artemisinin is a potential therapeutic agent for various diseases. Thus, this review is expected to encourage interested scientists to conduct further preclinical and clinical studies to evaluate these biological activities.

Artemisinin induces hormonal imbalance and oxidative damage in the erythrocytes and uterus but not in the ovary of rats

Artemisinin is an antimalarial drug previously reported to induce neurotoxicity and embryotoxicity in animal models. This study investigated the erythrocytes and reproductive toxicity potentials of artemisinin in female rats. Animals were randomly divided into four study groups of eight rats each. The control group (group I) received corn oil, the vehicle, while groups II-IV were orally exposed to 7, 35 and 70 mg kg(-1) day(-1) of artemisinin, respectively, by gastric intubation for 7 consecutive days. Subsequently, we evaluated the impact of artemisinin on the endocrine environment and selected markers of oxidative damage and antioxidant status of the erythrocytes, ovary and uterus. Artemisinin significantly increased hydrogen peroxide (H2O2) and malondialdehyde (MDA) levels and decreased catalase, glutathione peroxidase and superoxide dismutase activities in erythrocytes and uterus of rats compared with control group (p < 0.05). However, artemisinin did not alter ovarian MDA, H2O2, glutathione levels and catalase activity, while ovarian and uterine histological assessment revealed absence of visible lesions. Moreover, artemisinin significantly decreased follicle-stimulating hormone and increased progesterone levels compared with control (p < 0.05). Thus, these data suggest that in the absence of malarial parasite infection, artemisinin induced hormonal imbalance and oxidative damage in the erythrocytes and uterus but spared the ovary of rats.

Malaria control in Vietnam: the Binh Thuan experience

OBJECTIVE

The National Malaria Control Program (NMCP) in Vietnam is based on application of insecticide-treated bed nets (ITNs), spraying of insecticides and early microscopic diagnosis of malaria and treatment (EDTM) with artemisinin drugs. This study explores the implementation of the NMCP at provincial level and its impact on malaria incidence (mi) and prevalence in Binh Thuan in southern Vietnam.

METHODS

Data on implementation of EDTM, distribution of ITNs, annual mi and Plasmodium index (pi) were derived from intervention logbooks and surveillance records kept by the provincial Malaria Station since 1988. The relation between interventions and the change of pi over time was analysed with Generalized Estimating Equations.

RESULTS

Control activities focused on the highly endemic zones where ITNs were distributed free of charge to ethnic minority groups, including twice yearly re-impregnation, from 1992 onwards. This almost completely replaced insecticide spraying. Complete ITN coverage of these groups was achieved in 1995, constituting 40% of the entire population. In all malaria endemic communes, primary health care posts were consecutively upgraded or installed, mainly between 1992 and 1995, offering EDTM with artemisinin drugs free of charge. Before 1994, mi peaked to over 50/1000, pi to over 16% in the highly endemic zones. In 1998, these had decreased to below 9/1000 and 4% respectively. The effects of the interventions could not be discerned with statistical significance.

CONCLUSION

Malaria incidence and prevalence declined significantly in Vietnam, possibly due to the malaria control efforts, but coinciding with rapid socioeconomic changes.

In vivo assessment of drug efficacy against Plasmodium falciparum malaria: duration of follow-up

To determine the optimum duration of follow-up for the assessment of drug efficacy against Plasmodium falciparum malaria, 96 trial arms from randomized controlled trials (RCTs) with follow-up of 28 days or longer that were conducted between 1990 and 2003 were analyzed. These trials enrolled 13,772 patients, and participating patients comprised 23% of all patients enrolled in RCTs over the past 40 years; 61 (64%) trial arms were conducted in areas where the rate of malaria transmission was low, and 58 (50%) trial arms were supported by parasite genotyping to distinguish true recrudescences from reinfections. The median overall failure rate reported was 10% (range, 0 to 47%). The widely used day 14 assessment had a sensitivity of between 0 and 37% in identifying treatment failures and had no predictive value. Assessment at day 28 had a sensitivity of 66% overall (28 to 100% in individual trials) but could be used to predict the true failure rate if either parasite genotyping was performed (r(2) = 0.94) or if the entomological inoculation rate was known. In the assessment of drug efficacy against falciparum malaria, 28 days should be the minimum period of follow-up.

CV8, a new combination of dihydroartemisinin, piperaquine, trimethoprim and primaquine, compared with atovaquone-proguanil against falciparum malaria in Vietnam

OBJECTIVES

To study a new combination, based on dihydroartemisinin and piperaquine (CV8) and atovaquone/proguanil (Malarone) for treatment of uncomplicated falciparum malaria in Vietnam.

METHODS

Vietnamese adults with falciparum malaria were allocated randomly to treatment with dihydroartemisinin/piperaquine/trimethoprim/primaquine 256/2560/720/40 mg (CV8, n = 84) or Malarone 3000/1200 mg (n = 81), both over 3 days. Patients were followed-up for 28 days.

RESULTS

All patients recovered rapidly. The mean (95% CI) parasite elimination half-life of CV8 was 6.8 h (6.2-7.4) and of Malarone 6.5 h (6.1-6.9) (P = 0.4). Complete parasite clearance time was 35 (31-39) and 34 h (31-38) (P = 0.9). The 28-day cure rate was 94% and 95%, respectively (odds ratio 0.84, 95% CI 0.18-3.81). No significant side-effects were found.

CONCLUSION

CV8 and Malarone are effective combinations against multi-drug resistant falciparum malaria. CV8 has the advantage of a low price.

In vitro and in vivo potentiation of artemisinin and synthetic endoperoxide antimalarial drugs by metalloporphyrins

The in vitro potentiation of artemisinin by synthetic manganese porphyrin complexes has been recently reported (F. Benoit-Vical, A. Robert, and B. Meunier, Antimicrob. Agents Chemother. 43:2555-2558, 1999). Since the activity of artemisinin and synthetic antimalarial endoperoxides is related to their interaction with heme (S. R. Meshnick, A. Thomas, A. Ranz, C. M. Xu, and H. Z. Pan, Mol. Biochem. Parasitol. 49:181-190, 1991), an improvement of their efficiency may be expected in the presence of a synthetic metalloporphyrin having the same activating role as endogenous heme. With the aim to boost the activity of antimalarial endoperoxide drugs, we were thus led to evaluate the in vitro and in vivo potentiation of natural and synthetic drugs of this family by a nontoxic and cheap metalloporphyrin. The potentiation of artemisinin, beta-artemether, and arteflene (Ro 42-1611) by synthetic heme models is reported. In vitro studies on the chloroquine-resistant Plasmodium falciparum FcB1-Columbia strain indicate a synergistic effect of the manganese complex of meso-tetrakis(4-sulfonatophenylporphyrin) (Mn-TPPS) on the activity of artemisinin or beta-artemether, whereas this heme model has no influence on the activity of arteflene. A significant synergistic effect on rodent malaria was also observed in vivo between artemisinin and Mn-TPPS using Plasmodium vinckei petteri strain.

Combinations of artemisinin and quinine for uncomplicated falciparum malaria: efficacy and pharmacodynamics

Combinations of artemisinin and quinine for uncomplicated falciparum malaria were studied. A total of 268 patients were randomized to 7 days of quinine at 10 mg/kg of body weight three times a day (Q) or to artemisinin at 20 mg/kg of body weight followed by 3 (AQ3) or 5 (AQ5) days of quinine. Recrudescence rates were 16, 38, and 15% for the Q, AQ3, and AQ5 groups, respectively (P < 0.001). Recrudescence was associated with shorter parasite clearance time (PCT) and longer treatment after the blood smear had become negative (eradication time). However, classification of patients to outcome-recrudescence or radical cure-was correct in only 77% of patients. The population kinetics of the parasitemia was estimated with nonlinear mixed-effect models. Several models were tested, but the best model was a monoexponential decline of the parasitemia in which the mean parasite elimination half-life was shorter after artemisinin (5.1 h; 95% confidence interval [CI], 4.9 to 5.2 h) than after quinine (8.0 h [95% CI, 7.5 to 8.3 h]). Attempts to simulate the initial increase of the parasitemia did not result in better models with a biologically plausible interpretation. Recrudescence was associated with slower parasite clearance and a higher simulated terminal parasitemia (P(term)). The classification of patients to outcome groups based on P(term) was correct in 78% of patients. The data suggest that parasite strains with reduced sensitivity to quinine are prevalent in Vietnam, with slower parasite clearance and consequent recrudescence. A single dose of artemisinin induces rapid parasite reduction and lowers the value of P(term), but to prevent recrudescence, this should be followed by quinine for at least 3 days after parasite clearance, or 5 days in total.

Current status of artemisinin and its derivatives as antimalarial drugs

Artemisinin is a promising and a potent antimalarial drug, which meets the dual challenge posed by drug-resistant parasites and rapid progression of malarial illness. This review article focuses on the progress achieved during the last years in the production of artemisinin from Artemisia annua. The structure, biosynthesis and analysis of artemisinin and its mode of action are described. The review also focuses on clinical studies, toxicity studies, pharmacokinetics and activity of artemisinin related compounds. The production strategies including organic synthesis, extraction from plants, in vitro cultures and alternative strategies for enhancing the yields are also discussed.

Artemisinin derivatives for treating uncomplicated malaria

BACKGROUND

Artemisinin derivatives are a relatively new group of drugs with antimalarial properties. As resistance to other antimalarial drugs continues to increase, artemisinin drugs may be useful alternatives.

OBJECTIVES

The objective of this review was to assess the effects of artemisinin drugs for treating uncomplicated falciparum malaria.

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group trials register, the Cochrane Controlled Trials Register, Medline, Embase, Science Citation Index, Lilacs, African Index Medicus; conference abstracts and reference lists of relevant articles. We contacted organisations, researchers in the field and drug companies.

SELECTION CRITERIA

Randomised and quasi-randomised trials of artemisinin derivatives, alone or in combination with other antimalarials, compared with standard antimalarial treatments, in adults or children with uncomplicated falciparum malaria. Only trials where treatment was given by mouth or suppository were included. Comparisons between different artemisinin derivatives and treatment regimens were also included.

DATA COLLECTION AND ANALYSIS

Eligibility and trial quality were assessed and data were extracted independently by the two reviewers.

MAIN RESULTS

Forty-one trials involving over 5000 patients were included. Variation in study design and quality made synthesis of the data problematic. Allocation concealment was adequate in only two trials. Most data were from areas of multidrug resistant falciparum malaria in South East Asia. Compared with standard antimalarial treatments, artemisinin drugs showed fast parasite clearance and high cure rates at follow-up, provided the duration of treatment with artemisinin drugs was adequate. Combination with mefloquine improved sustained parasite clearance and was effective in multidrug resistant areas. When doses were adequate, the combination shortened the duration of treatment. We found no evidence that artemisinin drugs are more harmful than standard treatment drugs over a typical trial period of 28 days.

REVIEWER'S CONCLUSIONS

The evidence suggests that artemisinin drugs are effective and safe for treating uncomplicated malaria. There is no evidence from randomised trials that one artemisinin derivative is better than the others. In areas where there is mefloquine resistance, combination therapy with an artemisinin derivative appears to improve sustained parasite clearance compared with either drug alone.