Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024530 (malaria)
 44,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Since 1979 several derivatives of artemisinin have been synthesized and studied in China. Artemisinin suppositories, artesunate (oral or parenteral), intramuscular artemether and dihydroartemisinin tablets have all proved rapidly effective. In all, 2352 patients (2150 with Plasmodium falciparum and 202 with P. vivax) have been included in clinical trials from our centre. All preparations have been well tolerated. These drugs have now replaced chloroquine and quinine for the treatment of malaria in China.
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PMID:Clinical trials of artemisinin and its derivatives in the treatment of malaria in China. 805 27

Artemisinin and its derivatives are already registered and available in some east Asian countries, and will soon become so in some countries in Africa. Regulatory mechanisms need to be strengthened in tropical countries to ensure the quality, safety and efficacy of these valuable drugs. Steps also need to be taken to improve dissemination of scientific information. A consensus has been reached internationally on the role of artemisinin and its derivatives in the current treatment of malaria, and guidelines drawn up. Post-registration surveillance is needed to monitor, at country level, drug efficacy, safety, and quality.
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PMID:Regulation of drug use and post-registration surveillance. 805 32

In order to combat increasing problems with drug resistance in Plasmodium falciparum, Viet Nam has turned increasingly to the artemisinin derivatives. Oral and suppository formulations of artemisinin are produced from locally grown plants. These compounds have been rapidly effective in a large number of studies and have proved of particular value in severe malaria. Artemisinin suppositories are as effective as the parenteral drugs and offer the prospect of a simple, safe and inexpensive method of treating severe malaria in rural areas.
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PMID:An overview of the clinical use of artemisinin and its derivatives in the treatment of falciparum malaria in Viet Nam. 805 33

[14C]Artemisinin was taken up by Plasmodium falciparum in culture and concentrated in hemozoin. In vitro, hemin and artemisinin were found to undergo a chemical reaction forming two major products which were isolated by high-performance liquid chromatography (HPLC). The m/z values of the two products were 856 and 871. Thin-layer chromatography (TLC) and HPLC of hemozoin isolated from [14C]artemisinin-treated parasites showed that the majority of the hemozoin-associated radioactivity comigrated with the synthetic adducts. When [14C]artemisinin was incubated with isolated hemozoin, [14C]artemisinin disappeared from the solution in a time-dependent manner. Some of the radioactivity present in the treated hemozoin also comigrated with the adducts on TLC. Thus, artemisinin appears to react covalently with heme in malaria hemozoin both in vitro and in situ.
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PMID:The interaction of artemisinin with malarial hemozoin. 818 10

In the absence of a suitable malaria case definition, reliable surveillance data on the impact of malaria are not available. Determinants of case loads, including population movements, environmental changes, lack of political commitment and resources, and resistance to antimalarials and residual insecticides, work towards global deterioration. Some 90% of the Plasmodium falciparum burden is carried by Africa south of the Sahara. There, in 1992, the number of children under five years of age and exposed to high risk was about 106 million. Assuming a malaria attack rate of 0.5-1.5 per child per year, and a case fatality rate of 2%, annual clinical cases and malaria deaths in this population alone come to 53-160 million and 1-3 million, respectively. Roche, a pharmaceutical company with major research efforts in tropical medicine, in collaboration with research centers and international institutions, has recently set up a tropical medicine unit that coordinates and concentrates corporate efforts in this field. The unit aims to make affordable and innovative products available which are effective against major tropical diseases. A commercial product of the unit is Lariam, a major antimalarial used alone or in simultaneous or sequential combinations. The single dose combination of Lariam plus Fansidar (Fansimef) is particularly useful for stand-by or emergency oral therapy. Artemisinine, or its derivatives, followed by one to two doses of Lariam are effective against severe and multiresistant P. falciparum malaria. A new Roche peroxide antimalarial is currently in phase II clinical trials. The unit is also involved in research and development of malaria sporozoite and asexual blood stage vaccine candidates.
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PMID:Commitment of Roche in malaria and other tropical diseases. 825 5

Artemisinin (qinghaosu, QHS) is a promising new antimalarial agent that is effective against drug-resistant strains of malaria. The antimalarial activity of this drug appears to be mediated by an interaction of the drug's endoperoxide bridge with intraparasitic hemin. We have carried out a computer-assisted docking of QHS with hemin from various starting configurations and found that, in the most stable docked configuration, the endoperoxide bridge is in close proximity to the hemin iron. In contrast, an inactive analog, deoxyartemisinin (DQHS), docks in a different manner. Further computer analysis of the drug-hemin interaction might aid in the design of new QHS congeners.
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PMID:Molecular modeling studies of the artemisinin (qinghaosu)-hemin interaction: docking between the antimalarial agent and its putative receptor. 852 14

The study compared the clinical efficacy and safety of oral artemisinin and oral artesunate as well as artemisinin pharmacokinetics during and after resolution of falciparum malaria. Forty adults with symptomatic falciparum malaria were allocated at random to treatment with either oral artemisinin (500 mg single dose on day 1 followed by 250 mg twice daily for 4 d and then another 500 mg single dose on day 6) or with oral artesunate (100 mg single dose on day 1 followed by 50 mg twice daily for 5 d). Patients were admitted to hospital at the Kibaha Designated District Hospital, Kibaha, Tanzania for the duration of treatment. The patients were seen once weekly for 3 more weeks. The time to parasite clearance (PCT) after oral artesunate (26.4 +/- 3.6 h) was shorter (P = 0.002) than after artemisinin (31 +/- 3.6 h). The fever subsidence time (FST) after oral artesunate (18.9 +/- 4.0 h) was also shorter (P = 0.04) than after artemisinin (21.8 +/- 4.6 h). Parasites were detected in 4 (20%) and 7 (35%) patients after completing treatment with artesunate and artemisinin respectively. In these patients the parasitaemia reappeared at the 3rd or 4th week of follow-up. Standard haematology, blood biochemistry and urinalysis, performed before drug intake and again on days 6 and 14, were normal. No clinical abnormality was observed during the study period. Artemisinin plasma concentrations, determined by high performance liquid chromatography with post-column derivatization and detection by ultraviolet light, were followed up to 8 h after drug administration on days 1 and 6. Artemisinin absorption was rapid, the maximum plasma concentrations (Cmax) being attained at about 3 h. Artemisinin areas under the plasma concentration-time curve (AUC) and the Cmax values were about 6 times higher after the first dose on day 1 than on day 6. This decrease in artemisinin plasma concentration is suggestive of an increase in metabolic capacity due to pronounced autoinduction.
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PMID:Multiple dose pharmacokinetics of oral artemisinin and comparison of its efficacy with that of oral artesunate in falciparum malaria patients. 873 Mar 15

Artemisinin and its derivatives are endoperoxide-containing compounds which represent a promising new class of antimalarial drugs. In the presence of intraparasitic iron, these drugs are converted into free radicals and other electrophilic intermediates which then alkylate specific malaria target proteins. Combinations of available derivatives and other antimalarial agents show promise both as first-line agents and in the treatment of severe disease.
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PMID:Artemisinin and the antimalarial endoperoxides: from herbal remedy to targeted chemotherapy. 880 35

1. Atremisinin (qinghaosu) is a sesquiterpene endoperoxide derived from a plant which was used in Chinese herbal medicine for thousands of years. 2. Artemisinin and its derivatives have potent antimalarial activity, and are now being used clinically in much of the world. 3. The artemisinin derivatives have an unusual mode of action involving the iron-catalyzed generation of a carbon-centered free radical followed by the alkylation of malaria-specific proteins.
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PMID:The mode of action of the antimalarial artemisinin and its derivatives. 885 88

Artemisinin and its derivatives are renowned for their potent antimalarial activity. They have found their way into clinical use in many areas where malaria is endemic. The in vitro concentration at which artemisinin can inhibit 50% of the growth of Plasmodium falciparum ranges from 3 to 30 micrograms/L. The fat-soluble derivatives artemether and arteether are approximately twice as active. The water-soluble dihydro-artemisinin and artesunate are 4 to 5 times more active in vitro. Artemisinin is available only for oral and rectal administration. Absorption is incomplete and elimination is fast, with and elimination half-life of 2 to 5 hours. Plasma concentrations after a single 500 mg oral dose most often exceed 200 micrograms/L. Artesunate and artemether can be considered as prodrugs. Biotransformation into the active metabolite dihydro-artemisinin occurs rapidly--almost immediately for artesunate. The reported elimination half-life of artesunate is less than 1 hour, and for artemether the figure is 3 to 11 hours. The pharmacokinetics of dihydro-artemisinin are not yet completely clear. Elimination is probably also rapid, with an elimination half-life of a few hours. Arteether, dissolved in oil for intramuscular administration, has a much longer elimination half-life of over 20 hours. The clinical efficacy of this group of drugs is characterised by an almost immediate onset and rapid reduction of parasitaemia, with complete clearance in most cases within 48 hours. Efficacy is high even in areas with multidrug-resistant parasite strains. To prevent recrudescence with monotherapy of these compounds, treatment needs to be extended beyond the disappearance of parasites. After 5 days of therapy the rate of recrudescence is approximately 10%. Alternatively, combination with other drugs can be used. Combination with mefloquine is recommended for areas with multidrug-resistant P. falciparum.
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PMID:Clinical pharmacology and therapeutic potential of artemisinin and its derivatives in the treatment of malaria. 895 53


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