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PubMed1989

[Antimalarial action of alloxan and 5,6-diamino-2,4-dihydroxy-pyrimidine in Plasmodium berghei].

Three hours after iv administration of alloxan and 5,6-diamino-2,4-dihydroxy-pyrimidine to mice infected with chloroquine-sensitive (CS) and chloroquine-resistant (CR) strains of Plasmodium berghei, the 2 compounds showed remarkable antimalarial actions. Parasitemia in CS and CR infected mice were reduced by about 50%. Slight hemolysis was seen in mice treated with alloxan but not in mice treated with 5,6-diamino-2,4-dihydro-pyrimidine. Alloxan did not inhibit glutathione reductase activity and no alloxan-glutathione complex was produced. No relationship between the antimalarial effects of alloxan and hemolysis or GSH content were found. It is suggested that the antimalarial effects of the two agents may be due to the inhibition of dihydroorotic acid dehydrogenase.

Alloxan↗
PubMed1989

Evidence that the antimalarial activity of artemisinin is not mediated via intercalation with nucleotides.

The interaction of artemisinin, a new sesquiterpine lactone antimalarial drug, with some target macromolecules represented by calf thymus deoxyribonucleic acid (DNA) and the dinucleotide guanylyl (3----5) cytidine (GpC) was studied by 1H-NMR. There was no intercalation between artemisinin and DNA or GpC as judged by the lack in change of chemical shifts (delta delta) or coupling constants (delta J) of the C-13, C-14, and C-15 methyl groups of artemisinin. This conclusion was substantiated by studying the optical rotatory dispersion (ORD) between artemisinin and these target macromolecules. It is suggested that artemisinin exerts its antimalarial action via a mechanism different from that of the aminoquinolines antimalarial agents, possibly through the peroxygen linkage which is essential for artemisinin biological activity.

Acrylates↗
PubMed1986

Current practice in antimalarial drug prescribing in rheumatoid arthritis.

An analytic mail survey was conducted among Canadian and Australian rheumatologists to probe current prescribing practices for antimalarial agents. Ninety-six percent of respondents prescribed antimalarial therapy for rheumatoid arthritis with a preference for the use of hydroxychloroquine. The most frequently reported risk estimates for serious retinal toxicity were 0.01 and less than or equal to 0.001. Seventy-eight percent of rheumatologists reported 1 to 50% of patients refusing antimalarial therapy, usually because of concern regarding ocular toxicity. Our study indicates the importance of presenting the relevant risk:benefit data in an accurate and comprehensible form to potential recipients.

Antimalarials↗
PubMed1983

An in vitro assay system for the identification of potential antimalarial drugs.

Current models for antimalarial drug screening generally measure the survival of drug-treated rodents infected with Plasmodium berghei. Modifications of existing continuous culture methods for P. falciparum allow the rapid, accurate and economical determination of drug effects directly against the human pathogen. Parasite cultures can be maintained in RPMI 1640 medium supplemented with human or rabbit serum or with hypoxanthine-supplemented bovine serum. The antiparasite effects of four drugs, chloroquine, chloramphenicol, clindamycin, and halofuginone, are identical in these sera; drugs can be screened routinely against P. falciparum grown in bovine serum supplemented with hypoxanthine. Drug effects may be rapidly and accurately determined by monitoring the incorporation of 3H-hypoxanthine into parasite nucleic acids. Results obtained with this technique are highly correlated with those derived from visual counting of parasites in thin blood films. Compounds with antimalarial activity in culture may be further screened by measuring the effects of serum obtained from drug-treated rabbits on parasites in culture. The advantages of this system over models currently used for antimalarial screening are discussed.

Animals↗
PubMedDate not supplied

Analysis of treatment terminations with gold and antimalarial compounds in rheumatoid arthritis.

Life table analysis was used to determine the incidence of treatment termination in rheumatoid arthritis patients after initial therapeutic courses of gold (93) and antimalarial compounds (101). Patients treated with antimalarial compounds tended to terminate treatment sooner than those receiving gold. The most common reasons for discontinuing antimalarial therapy were lack of initial benefit and loss of response to the drug. Clinical and laboratory characteristics of patients at onset of therapy did not influence failure rates to a great extent.

Adult↗
PubMed1995

Antimalarials during pregnancy: a cost-effectiveness analysis.

Antenatal clinics (ANC) provide an avenue for interventions that promote maternal and infant health. In areas hyperendemic for Plasmodium falciparum, malaria infection during pregnancy contributes to low birth weight (LBW), which is the greatest risk factor for neonatal mortality. Using current data and costs from studies in Malawi, a decision-analysis model was constructed to predict the number of LBW cases prevented by three antimalarial regimens, in an area with a high prevalence of chloroquine (CQ)-resistant malaria. Factors considered included local costs of antimalarials, number of ANC visits, compliance with dispensed antimalarials, prevalence of placental malaria, and LBW incidence. For a hypothetical cohort of 10,000 women in their first or second pregnancy, a regimen consisting of one dose of sulfadoxine-pyrimethamine (SP) in the second trimester followed by a second dose at the beginning of the third trimester would prevent 205 cases of LBW at a cost of US$ 9.66 per case of LBW prevented. A regimen using a treatment dose of SP followed by CQ 300 mg (base) weekly would prevent 59 cases of LBW at a cost of $62 per case prevented, compared with only 30 cases of LBW prevented at a cost of $113 per case when the regimen involves initial treatment with CQ (25 mg/kg) followed by CQ 300 mg (base) weekly. In areas hyperendemic for CQ-resistant P. falciparum, a two-dose SP regimen is a cost-effective intervention to reduce LBW incidence and it should be included as part of the antenatal care package.

Antimalarials↗
PubMed1995

Self-medication with antimalarial drugs in Dar es Salaam, Tanzania.

A hospital-based cross-sectional study was conducted in Dar es Salaam, Tanzania, using a questionnaire to assess the extent of self-medication with antimalarial drugs and malaria treatment-seeking behaviour among patients attending out-patient treatment at Mnazi mmoja dispensary. It was found that 15.3% of respondents admitted to having ever used malaria chemoprophylaxis while 8.0% reported to be current users of chemoprophylaxis. Among the current users of malaria chemoprophylaxis, some reported having used quinine and Fansidar. While 71.7% reported having treated themselves with home-kept antimalarial drugs for a suspected malaria fever, 14.7% consulted traditional healers. The data suggest the need for increasing public awareness on malaria and appropriate use of antimalarial drugs.

Antimalarials↗
PubMed1995

Mode of action of iron(III) chelators as antimalarials. III. Overadditive effects in the combined action of hydroxamate-based agents on in vitro growth of Plasmodium falciparum.

Hydroxamate-based iron(III) chelators exhibit potent antimalarial effects on the asexual stages of Plasmodium falciparum grown in vitro. Antimalarial activity varies with the parasite growth stage and the drug permeation properties. The hydrophilic drug desferrioxamine (DFO) is ineffective on early stages (ring forms) of the parasite due to its poor permeability but irreversibly blocks the growth of advanced stages of parasites. On the other hand, hydrophobic reversed siderophores (RSFs) are more membrane permeable and affect all parasite developmental stages; they affect ring forms irreversibly and trophozoite/schizont forms reversibly and at relatively faster rates, compared with DFO. These observations have provided the basis for postulating a possible overadditive action of the two, distinctly acting, iron chelator types for enhanced antimalarial activity. This was assessed in this study by using novel fast-acting chelators such as RSF derivatives (RSFleum2 and RSFm2) in combination with the relatively slow-acting DFO. Parasite growth was assessed in terms of nucleic acid synthesis and parasitemia. The results indicate that, at any molar ratios of the two types of drugs, the combined inhibitory effect was faster and more potent than the sum of individual effects. The combined drug action showed neither additive nor independent but overadditive properties, as well as sustained inhibition even after drug removal. The potentiating action of RSFs on the long-lasting effects of DFO on parasite growth conformed with the postulated mechanistic model of iron chelator action and iron handling by parasites. Iron chelator combinations might be of therapeutic value.

Animals↗
PubMed1994

Antimalarial agents and lupus.

Antimalarials are under-utilized, disease-modifying agents that are useful in the management of lupus erythematosus. Antimalarials can promote a remission in non-organ-threatening lupus and decrease its risk of dissemination. They are especially useful for cutaneous and inflammatory joint disease and have modest actions in improving serositis, fatigue, and cognitive dysfunction. As agents that do not depress the bone marrow or promote opportunistic infections, antimalarials have potential applications in combination with other antilupus medications and with each other.

Antibodies, Antiphospholipid↗
PubMed1993

[Studies on residual antimalarial activity of tripynadine in mice and monkeys].

This paper reports the experiments in which tripynadine free base at a dose 4.5 times that of ED50 was given to mice by intragastric administration. On the 20th day following the administration the mice were inoculated with 1 x 10(7) RBC infected with Plasmodium berghei ANKA strain. The infection rate was zero, implying that all mice had acquired protection. Although the residual activity time of tripynadine phosphate was longer than that of tripynadine free base or piperaquine phosphate, but tripynadine phosphate caused vomiting in monkeys during the medication. The residual antimalarial activity of tripynadine hydroxynaphthoate was less than that of tripynadine phosphate or tripynadine free base. A total dose of 200 mg/kg of tripynadine free base ensured residual antimalarial activity against P. cynomolgi bastianellii for 20 days. However, the residual activity decreased evidently when the total dose was reduced to 100 mg/kg. In short, it seems that the residual antimalarial activity of tripynadine free base is slightly less than that of piperaquine in monkeys.

Animals↗
PubMed1993

The relevance of antimalarial therapy with regard to thrombosis, hypercholesterolemia and cytokines in SLE.

Hydroxychloroquine has several less well-known actions that may have clinical relevance in treating systemic lupus erythematosus (SLE). (1) Hydroxychloroquine has a possible anti-thrombotic action. It is a platelet inhibitor and appears to decrease the risk of thromboembolism in patients with anticardiolipin antibodies. (2) Hydroxychloroquine is associated with lower serum cholesterol and low-density lipoprotein levels compared to those present in patients who are taking corticosteroids but not antimalarials for SLE. (3) It may also decrease abnormal levels of cytokines. Interleukin-6 (IL-6), soluble CD8 and soluble IL-2 receptors (sIL-2R) are lower in patients taking antimalarials compared to those on corticosteroids alone or on neither medication. Serum levels of CD8 and sIL-2R decrease after 6 weeks of hydroxychloroquine treatment. These findings may help explain the favorable response of SLE patients treated with antimalarials.

Animals↗
PubMed1995

[For new antimalarial drugs: the methods of fundamental research].

Research in new antimalarial drugs has too long been limited to a only pharmacological approach with its four main modalities: isolation of compounds from medicinal plants, oriented or not screening of varied molecules, molecular ingeniery modifying structure of wellknown drugs in order to improve their efficacy, products reversing resistance to antimalarial drugs (anti-Pfmdr). Important success has been obtained by these ways but the possibility of new discoveries seems to be limited. It is time certainly to concentrate efforts no more on the drug itself but on the real target i.e. Plasmodium or malaria disease. Our knowledge of Plasmodium biology and of pathophysiological mechanisms in malaria are still very limited. This kind of study comes up against many difficulties (plasmodial intracellular parasitism, parasitic specificity of Plasmodium parasites in Man, etc). Nevertheless, only a huge effort in fundamental research will open new perspectives in antimalarial therapeutics by identifying possible targets for new compounds from which pharmaccutal industry will be able to develop new medicines.

Antimalarials↗
PubMed1995

Pharmacology and pharmacokinetics of new antimalarials.

Chloroquine-resistant Plasmodium falciparum is now widespread in Africa, requiring new drugs for the control of both non-severe and severe forms of the disease. For non-severe malaria, pyrimethamine-sulphadoxine, an antifolate combination antimalarial, is at present efficacious, single-dose and cheap; important characteristics for treatments in Africa. However, alternative combinations are being investigated which are intrinsically more active, less toxic and with shorter elimination half-lives. In theory, short half-life compounds reduce the selective pressure for resistance, which may be a major determinant of the useful therapeutic life of an antimalarial drug. The potential advantages/disadvantages of alternative antifolates is discussed. While the use of mefloquine and halofantrine in Africa is at present limited by cost, these drugs are likely replacements for the antifolates when parasite resistance arises. For severe, life-threatening falciparum malaria, quinine remains the treatment of choice. In contrast to quinine, artemether rapidly reduces the viability of circulating, ring-stage parasites, produces more rapid parasite clearance and may reduce the length of coma, but does not significantly reduce the mortality of severe malaria which remains at about 15% even with optimal management. It seems unlikely that chemotherapy, even with "new" antimalarials, will reduce this high figure. Other strategies are required.

Africa↗
PubMed1996

Role of antimalarials in rheumatoid arthritis--the British experience.

Antimalarials have been used to treat rheumatoid arthritis (RA) for over 40 years, the first report of suggestive efficacy being published in 1951. Over the years they have become part of the established treatment of RA being one of a category of drugs referred to as disease modifying anti-rheumatic drugs (DMARDs). The onset of action with antimalarials is slow. Most patients use these drugs in combination with non-steroidal anti-inflammatory drugs (NSAIDs) and analgesics. This article reviews the evidence for the efficacy of antimalarials, their place in comparison to other DMARDs and comments on the current use in RA as perceived in British rheumatology.

Antimalarials↗
PubMed1997

Utilisation of antimalarial drugs by pregnant women attending the antenatal clinic at Muhimbili Medical Centre, Dar es Salaam.

Two hundred women in early second trimester were recruited in a study to monitor the utilisation of antimalarial drugs prescribed for prophylaxis or treatment of malaria during their attendance at the antenatal clinic of Muhimbili Medical Centre. Information regarding the use of antimalarial drugs was obtained during an interview using a structured questionnaire and antenatal cards. The study revealed that 51.5% had taken antimalarials for treatment of acute malaria while 23.5% had taken for prophylaxis. There was thus a total exposure of 75%. most of them were exposed to choloroquine (69.5l%). There was no statistically significant association between the taking of chloroquine and its presence in urine and between the level of education and the taking of chloroquine prophylactically.

Adolescent↗
PubMed1998

[New antimalarial drugs].

Resistance of Plasmodia to available antimalarials is becoming very frequent. Discovering new drugs in this field is therefore a health priority. Only two new antimalarials appeared in the last few years: artemether IM (Paluther) for the treatment of severe malaria and a chloroquine-proguanil combination (Savarine) for the malarial chemoprophylaxis. Several other new molecules are under investigation. Only a few of them result from a targeted pharmacological research. On the other hand, the clinical and biological evaluation of new antimalarials is often conducted without respect of the international industrial guidelines and will probably fail to offer all the guarantees of efficacy and safety required for registration in western countries.

Antimalarials↗
PubMed1996

Second-generation antimalarial endoperoxides.

Artemisinin, derived from a Chinese herbal remedy, is a potent peroxide-containing antimalarial. New types of peroxides, derived from this structure, as well as other naturally occurring antimalarial peroxides, have been synthesized and found to have potent antimalarial activities. Studies on the activities, modes of action, and toxicities of these compounds are discussed here by Steven Meshnick and colleagues.

Journal Article↗
PubMed2005

Antimalarial remedies in French Guiana: a knowledge attitudes and practices study.

A "knowledge attitudes and practices" study about malaria treatments was undertaken in French Guiana, along with an ethnopharmacological study. One hundred and seventeen people from five different groups and nationalities (Creole, Palikur, Galibi, Brazilian, and European) answered the questionnaire. The results were analysed using univariate and multivariate statistical analysis. First, we evaluated the overall knowledge about malaria from the interviewed people. According to bio-medical concepts, we noticed that they have a good knowledge of this illness. Secondly, we studied the treatment used by sick people during their last malaria attack. We demonstrated that, although bio-medical treatment is available in this area, people use both modern drugs and traditional remedies. Finally, preventive attitudes have been examined. One-third of the interviewed people drink regularly some herbal remedy to prevent febrile illnesses and malaria, thus displaying a strong concern about this disease. The ethnopharmacological study highlighted the frequent use of traditional remedies, along with their mode of preparation and administration. A total of 34 different species (both from flora and fauna) have been registered as antimalarial. Twenty-seven are used for curative purposes, 20 as preventive and 13 of them are used for both purposes. Quassia amara (Simaroubaceae) whose antimalarial activity has already been demonstrated was the species most frequently used as antimalarial for curative and preventive purposes.

Adult↗