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PubMedDate not supplied

Chloroquine, sulfadoxine-pyrimethamine and amodiaquine efficacy for the treatment of uncomplicated Plasmodium falciparum malaria in Upper Nile, south Sudan.

The current first-line and second-line drugs for Plasmodium falciparum malaria in South Sudan, chloroquine and sulfadoxine-pyrimethamine (SP), were evaluated and compared with amodiaquine, in an MSF-Holland-run clinic in eastern Upper Nile, South Sudan from June to December 2001. Patients with uncomplicated malaria and fever were stratified by age group and randomly allocated to one of 3 treatment regimes. A total of 342 patients was admitted and followed for 14 d after treatment. The dropout rate was 10.2%. Of those who completed the study, 104 were treated with chloroquine (25 mg/kg, 3 d), 102 with SP (25 mg/kg sulfadoxine and 1.25 mg/kg pyrimethamine, single dose) and 101 with amodiaquine (25 mg/kg, 3 d). Adequate clinical response was observed in 88.5% of patients treated with chloroquine, 100% of patients treated with SP and 94.1% of patients treated with amodiaquine. In children aged < 5 years, the success rate was lower: 83.3% for chloroquine and 93.0% for amodiaquine. In adults no treatment failures were found, but children aged 5-15 years showed intermediate levels. In addition, we determined the initial genotypes of dhfr and dhps of 44 isolates from the SP-treated group and > 80% were found to be wild type for dhfr and 100% for dhps. Two percent of isolates had a single mutation and 16% had double mutations of dhfr. These data are in full agreement with the clinical effectiveness of SP. A change in malaria treatment protocols for South Sudan is recommended.

Adolescent↗
PubMedDate not supplied

Artesunate and sulfadoxine-pyrimethamine combinations for the treatment of uncomplicated Plasmodium falciparum malaria in Uganda: a randomized, double-blind, placebo-controlled trial.

Drug-resistant malaria is spreading in Africa. The few available drugs might be safeguarded if combined with an artemisinin derivative. We investigated the efficacy, safety, and tolerability of 2 combinations of artesunate with sulfadoxine-pyrimethamine (SP) in a mesoendemic region in Uganda with SP resistance, from September 1999 to June 2000. In a randomized, double-blind, placebo-controlled trial, 420 children aged 6-59 months with uncomplicated Plasmodium falciparum malaria were assigned SP alone (25 mg/kg sulfadoxine, 1.25 mg/kg pyrimethamine) or combined with artesunate (AS; 4 mg/kg/d) for either 1 d (SPAS1) or 3 d (SPAS3). Children were followed-up for 28 d. Day 14 cure rates were 84.6% (99/117) with SPAS3 and 61.9% (73/118) with SPAS1 compared with 55.8% (86/154) with SP. Corresponding day 28 results were 74.4% (87/117) and 45.2% (52/115) compared with 40.5% (62/153). A significant improvement was obtained with the addition of 3 d, but not 1 d, of artesunate (risk ratio [RR] = 1.5, 95% CI 1.3-1.8 at 14 d and RR = 1.8, 95% CI 1.5-2.3 at 28 d). Both AS regimens achieved significantly faster parasite clearance and lower gametocyte carriage. All drug regimens were well tolerated, but SP alone was ineffective. Treatment efficacy improved with SPAS3 but the cure rate at day 28 was modest. The combinations were well tolerated and safe. In areas where SP resistance is prevalent other combinations should be considered.

Antimalarials↗
PubMedDate not supplied

Population-based validation of dihydrofolate reductase gene mutations for the prediction of sulfadoxine-pyrimethamine resistance in Uganda.

Mutations in the dihydrofolate reductase gene (dhfr) of Plasmodium falciparum have been proposed as molecular markers for the surveillance of sulfadoxine-pyrimethamine (SP)-resistant malaria, but such proposals have not been validated. At 7 Ugandan sites in 1999, we determined the population-based prevalence of infections with mutations and the mutant allele frequency of dhfr codons 108, 51, and 59 using a random sample of infected individuals aged 1-45 years. Sulfadoxine-pyrimethamine treatment failure was independently estimated by in vivo tests in 327 children aged 6-59 months with clinical malaria. The prevalence of infections with the single point mutations and the dhfr codons 108 and 51 mutant allele frequency were not correlated to SP treatment failure. However, the dhfr codon 59 mutant allele frequency was positively correlated to SP treatment failure (r = 0.72, P = 0.06). The ratio of the infections with the mutant to wild genotype (M/W) and that of the mutant to wild allele (MA/WA) had the same values. Both dhfr codon 59 M/W and MA/WA ratio were significantly and positively correlated to SP treatment failure (r = 0.73, P = 0.05). Moreover, the prevalence of infections with only 2 mutations (Asn-108 plus Ile-51) was significantly and inversely correlated to the prevalence of infections with 3 mutations (Asn-108 plus Ile-51 plus Arg-59) (r = 0.92, P = 0.004), suggesting the stepwise accumulation of the dhfr mutations is Asn-108 Ile-51 Arg-59 and further supporting the idea of using the dhfr codon 59 M/W ratio as a molecular index for the prediction of SP treatment failure. Atthe population level, the dhfr codon 59 M/W ratio is a simple and stable index for the estimation of SP treatment failure.

Adolescent↗
PubMedDate not supplied

High level of resistance of Plasmodium falciparum to sulfadoxine-pyrimethamine in children in Tanzania.

In many areas of tropical Africa affected by chloroquine-resistant Plasmodium falciparum, a combination of sulfadoxine and pyrimethamine (S-P) is used for alternative medication, especially in young children. In Magoda village in Muheza District, north-eastern Tanzania, 38 children 1-10 years of age were enrolled in a therapeutic study of S-P in July 1994. All had monoinfections of P. falciparum and an asexual parasite count of 1000-80,000/microL of blood. S-P was given as a single dose corresponding to 0.8-1.4 mg pyrimethamine/kg body weight. Of the 38 children followed up to day 7, 10 showed an S/RI response, 26 an RII response, and 2 an RIII response. Older children had lower pre-treatment parasitaemia and a better therapeutic response than younger children. Among the various contributory factors responsible for the poor therapeutic result, drug pressure from a prophylactic intervention with weekly dapsone-pyrimethamine between May 1993 and May 1994 seems to have been the most important.

Animals↗
PubMed2004

Comparison of chlorproguanil-dapsone with sulfadoxine-pyrimethamine for the treatment of uncomplicated falciparum malaria in young African children: double-blind randomised controlled trial.

BACKGROUND: Increasing resistance to sulfadoxine-pyrimethamine is leading to a decline in its effectiveness. We aimed to assess the safety profile of chlorproguanil-dapsone (CD), and to compare the safety and efficacy of this drug with that of sulfadoxine-pyrimethamine (SP) as treatment for uncomplicated falciparum malaria. METHODS: We undertook a double-blind, randomised trial in 1850 consecutively recruited children with uncomplicated falciparum malaria, pooling data from five African countries. Analyses were based on all randomised patients with available data. FINDINGS: CD was significantly more efficacious than SP (odds ratio 3.1 [95% CI 2.0-4.8]); 1313 patients (96%) given CD and 306 (89%) given SP achieved acceptable clinical and parasitological response by day 14. Adverse events were reported in 46% and 50% of patients randomised to CD and SP, respectively (treatment difference -4.4%, [95% CI -10.1 to 1.3]). Haemoglobin in the CD group was significantly lower than in the SP group at day 7, a difference of -4 g/L (95% CI -6 to -2). Mean day 14 haemoglobin (measured only for the small number of patients whose day 7 data caused concern) was 94 g/L (92-96) and 97 g/L (92-102) after CD and SP, respectively. Glucose-6-phosphate dehydrogenase deficient patients on CD had greater odds than those on SP of having a fall of 20 g/dL or more in haemoglobin when baseline temperature was high. Methaemoglobinaemia was seen in the CD group (n=320, mean 0.4% [95% CI 0.4-0.4]) before treatment, 4.2% (95% CI 3.8-4.6) (n=301) at day 3, and 0.6% (0.6-0.7) (n=300) at day 7). INTERPRETATION: CD had greater efficacy than SP in Africa and was well tolerated. Haematological adverse effects were more common with CD than with SP and were reversible. CD is a useful alternative where SP is failing due to resistance.

Africa↗
PubMed2001

Novel alleles of the Plasmodium falciparum dhfr highly resistant to pyrimethamine and chlorcycloguanil, but not WR99210.

We have expressed dhfr alleles of Plasmodium falciparum in the budding yeast, Saccharomyces cerevisiae, and used this yeast model to identify single amino acid substitutions that confer high level pyrimethamine resistance on the background of the triple mutant dhfr (I51+R59+N108). Mutations in three clusters were identified: codons 50-57, 187-193, and 213-214. Several mutations previously identified in field samples were also isolated, including codons 50 and 164. The I164L mutation is of particular interest, because the quadruple mutant genotype (N51I+C59R+S108N+I164L) encodes an enzyme that is no longer inhibited by pyrimethamine, rendering sulfadoxine/pyrimethamine (SP; Fansidar) clinically ineffective. Thirty-six novel alleles were tested to determine their sensitivity to chlorcycloguanil and WR99210, two DHFR inhibitors that are in clinical and pre-clinical development, respectively. Chlorcycloguanil is effective against parasites that carry the triple mutant allele, but in vitro analysis has suggested that chlorcycloguanil will be clinically ineffective against parasites that carry the quadruple mutant allele of dhfr. In our screen, 23 of 36 novel strains were as resistant to chlorcycloguanil as the quadruple mutant, and one strain was 10-fold more resistant. WR99210 is still effective in the nM range against parasites that carry the quadruple mutant allele. In the preliminary screen, 31 of 36 novel alleles were as sensitive to WR99210 as the quadruple mutant. Detailed analysis of the remaining five showed that four of the five had IC(50) values in the same range as the quadruple mutant, and one, N51I+C59R+S108N+E192G, had an IC(50) value about fivefold higher. This result suggests that WR99210 and related compounds will be clinically effective against quadruple mutants currently found in Southeast Asia and South America and against most novel alleles that could be selected on the background of the triple mutant genotype now prevalent in East Africa.

Alleles↗
PubMed2002

[In vivo sensitivity of Plasmodium falciparum to amino-4-quinolines and sulfadoxine pyrimethamine in Agou (Ivory Coast)].

A comparative study of the in vivo sensitivity of Plasmodium falciparum to amodiaquine versus chloroquine has been made among children in Agou (south Côte d'Ivoire). In case of resistance to these drugs, the association of sulfadoxine-pyrimethamine was administered and followed by a J14 checking. We have noticed: (1) 8.47% of amodiaquine resistance versus 36.96% of chloroquine resistance (all these resistances are from type II), (2) a good clinical efficiency of the 4 amino quinolines. Only 1.69% of the subjects having resistant stocks to amodiaquine have gone feverish down to J7 whereas 10.47% of subjects have clinically resisted to chloroquine, (3) a good tolerance of drugs and an excellent clinical and parasitological efficiency of the second intention treatment. These data are in favour of using first the 4 amino quinolines (particularly the amodiaquine) in the treatment of simple bout of malaria to Plasmodium falciparum in this region. In case of resistance to these drugs, we recommend the combination sulfadoxine-pyrimethamine.

Adolescent↗
PubMed1979

Determination of plasma concentrations of dapsone, monoacetyl dapsone and pyrimethamine in human subjects dosed with maloprim.

A high-performance liquid chromatographic method was developed to enable dapsone, monoacetyl dapsone and pyrimethamine to be measured simultaneously in plasma samples from volunteers in England and Malaysia who had been dosed with Maloprim. Mean half-lives of 25 and 80 h were calculated for dapsone and pyrimethamine, respectively, but there was wide individual variation. All subjects were found to be classifiable as "slow acetylators".

Adult↗
PubMed1989

Simultaneous determination of pyrimethamine and mefloquine in human plasma by high-performance liquid chromatography with ultraviolet detection.

A rapid, sensitive and selective method was developed for the simultaneous determination of pyrimethamine and mefloquine, two of the active ingredients of Fansimef, in human plasma. The procedure involved extraction of the compounds and the internal standard nitrazepam from basified plasma with dichloromethane and chromatography on a C18 column (microBondapak, 300 X 3.9 mm I.D.) with acetonitrile-phosphate buffer as the mobile phase and UV detection at 222 nm. The limit of quantification was 10 ng/ml for both substances, using a 1-ml plasma specimen. The mean inter-assay precision was 2.8% for pyrimethamine and 4.7% for mefloquine up to 800 ng/ml. The practicability of the method was demonstrated by the analysis of more than 1200 plasma samples from several pharmacokinetic studies involving single-dose administration of Fansimef to both patients and volunteers.

Antimalarials↗
PubMed2002

High-performance liquid chromatographic assay for the simultaneous determination of sulfadoxine and pyrimethamine from whole blood dried onto filter paper.

A method using solid-phase extraction and high-performance liquid chromatography is evaluated for the simultaneous determination of sulfadoxine and pyrimethamine from 0.1 ml of whole blood dried onto filter paper. Extraction recoveries are about 60% for both drugs. The coefficient of variation for intra-assay precision, inter-assay precision and accuracy is less than 10% for sulfadoxine (10-100 microg/ml) and pyrimethamine (1-10 microg/ml).

Antimalarials↗
PubMed1997

Simultaneous determination of pyrimethamine and sulphadoxine in human plasma by high-performance liquid chromatography after automated liquid-solid extraction.

A high-performance liquid chromatographic method with ultraviolet detection is described for the simultaneous measurement of pyrimethamine and sulphadoxine in human plasma. After an automated liquid-solid extraction on a C8 cartridge, the compounds are separated on a C18 column by isocratic elution; the mobile phase is methanol-acetonitrile-water (10:25:65, v/v/v) with triethylamine (1%) and adjusted to pH 5.6 with phosphoric acid. The eluent is monitored with an ultraviolet detector at 240 nm. The limit of quantification was 10 ng/ml for pyrimethamine and 22 microg/ml for sulphadoxine. No chromatographic interferences can be detected from endogenous compounds, other anti-malarial drugs or major drugs used for the treatment of children. Sulphadimethoxine is used as an internal standard. The method is accurate and precision is good with relative standard deviations lower than 6%. The chromatographic procedure takes 11 min. The method is comparatively rapid, simple, sensitive and can be used for therapeutic drug monitoring, clinical and pharmacokinetic studies.

Automation↗
PubMed2002

[Treatment of subclinical congenital toxoplasmosis by sulfadiazine and pyrimethamine continuously during 1 year: apropos of 46 cases].

UNLABELLED: In France, most of children suffering from congenital toxoplasmosis have an infraclinic or moderate type at birth. This study aimed at evaluating, on the mid term, tolerance and results of postnatal treatment previously given in severe toxoplasmosis. METHODS: A retrospective study considered 46 children with a mild or moderate congenital toxoplasmosis treated over 12 months with sulfadiazine-pyrimethamine and treatment was completed since three months. RESULTS: Five children suffered from a lesion of chorioretinitis during treatment and two after. After a mean follow-up of 27.1 months, ten children (21.7% 95%CI [12.1-35.9]) had at least one ocular injury. Specific IgG titers and immune load were diminished to become almost non-existent at the end of the year of treatment (respectively p < 10(-5) and p = 0.0005). No thrombocytopenia was observed. Twenty-three children (50%) had at least one episode of neutropenia < 1000/mm3, 14 had only one, nine presented two or more installment. None was followed by an infection. CONCLUSION: This therapeutic pathway is more demanding but shorter than those usually offered when associating pyrimethamine-sulfadiazine. Yet, it does give identical result on the mid term. Longer follow-up is needed to appreciate. Active molecule on cysts should be introduced.

Age Factors↗
PubMed1997

Simple detection of in vivo genotoxicity of pyrimethamine in rodents by the modified alkaline single-cell gel electrophoresis assay.

We tested the genotoxicity of pyrimethamine in 5 mouse and rat organs (liver, lung, kidney, spleen, and bone marrow) using a modified alkaline single-cell gel electrophoresis (SCG) (Comet) assay. Mice and rats were sacrificed 1, 3, 6, and 24 h after oral administration of the drug at 50 and 120 mg/kg, respectively. Nuclei were isolated from each tissue and evaluated for DNA migration. Pyrimethamine induced DNA damage in cells of the liver, kidney, and lung in both species. For mice, DNA damage persisted in the liver for 24 h, while it peaked in the lung and kidney at 6 and 24 h, respectively. For rats, DNA damage in the liver peaked at 1 h and returned to almost control level at 24 h. Genotoxicity in the spleen was only observed in mice. Our results suggest that the SCG technique, using isolated nuclei can be applied to rats and mice and that the optimal sampling time is different for different organs and species.

Animals↗
PubMed2002

Pharmacokinetics of sequential and simultaneous treatment with the combination chloroquine and sulfadoxine-pyrimethamine in acute uncomplicated Plasmodium falciparum malaria in the Philippines.

The efficacy and kinetics of the combination chloroquine plus sulfadoxine-pyrimethamine (CQ + SP), given sequentially and simultaneously, were investigated in 32 patients with acute uncomplicated Plasmodium falciparum malaria in Palawan Island, the Philippines. Group 1 with 11 patients received oral CQ 25 mg/kg bw over 3 days followed by a single dose of SP (three tablets 250 mg S + 25 mg P) on Day 4 (CQ0 + SP4). Group 2 with 21 patients received a loading dose of CQ 10 mg/kg plus a single dose of SP three tablets on Day 0, and doses of CQ on Days 1 and 2 (CQ0 + SP0). Patients were followed-up for 28 days until after the clinical and parasitological remission of the disease. Serum samples for CQ, des-ethylchloroquine (DCQ), S and P levels were assayed by high-pressure liquid chromatography with UV and spectrofluorometric detection (HPLC-SF) to determine effective therapeutic concentrations achieved. Parasite and fever clearance times (PCT and FCT) in Group 1 were 48 and 33.5 h, respectively, and 39 and 24 h in Group 2. The parasite elimination half-life (pt1/2) in the CQ + SP0 group was 2.5 h, significantly shorter than the CQ + SP4 group of 5.7 h (P=0.006). Late-treatment failures (R I) were observed in 2/11 patients in Group 1 and in 2/21 patients in Group 2. Serum CQ and DCQ concentrations were effectively adequate. Group 1 pharmacokinetic parameters showed a median maximum concentration (Cmax), area under the curve (AUC) and elimination half-life (t1/2) of 285 ng/ml, 2299 day ng/ml and 5.7 days for CQ, and 89 ng/ml 1845 day ng/ml and 7.3 days for DCQ, respectively. SP was not assayed in Group 1 because of very limited time points. In Group 2, the median Cmax, AUC and t1/2 for CQ and DCQ were at 283 ng/ml 1980 day ng/ml and 5.9 days for CQ and 220 ng/ml, 2680 day ng/ml and 8.5 days for DCQ, respectively. For S and P, the median Cmax, AUC and t1/2 were at 169 microg/ml, 2758 day ng/ml and 10.9 days for sulfadoxine, and 591 ng/ml, 3029 day ng/ml and 2.9 days for pyrimethamine, respectively. Both regimens were well tolerated with a minimum of side-effects, mainly nausea and vomiting. The combination CQ + SP administered simultaneously on Day 0 is more efficacious than when administered sequentially. In the absence of an alternative treatment for acute uncomplicated malaria, this combination is well tolerated, and has an advantage over CQ or SP monotherapy, especially in countries where one drug is still highly effective.

Acute Disease↗
PubMed1995

[Pyrimethamine-sulfadiazine resistant cerebral toxoplasmosis in AIDS].

A 48-year-old man with known HIV infection for 4 years was admitted with a 2-week history of increasing brachio-facial paraesthesiae of the left side of the body and pains in the head and neck. Physical examination also showed discrete slowing of mental activity and oral candidiasis. Toxoplasmosis serology showed a low titre with a borderline IgM titre. Cranial computer tomography showed two confluent contrast medium concentrating foci in the region of the head of the caudate nucleus and the right internal capsule. Because toxoplasmosis encephalitis was suspected, treatment was started with sulfadiazine (1 g four times daily), pyrimethamine (25 mg four times daily), folic acid (15 mg daily) and dexamethasone (8 mg three times daily). After 19 days of treatment there was no clinical improvement, and a check CT scan showed worsening with increased oedema of the cerebellar medulla, compression of the lateral ventricles and a mid-line shift of 5 mm. Since the Sabin-Feldman test titre had increased, and there was no evidence to suggest a lymphoma or a viral or fungal infection, toxoplasmosis resistant to standard therapy was postulated, and treatment was started with clindamycin (600 mg three times daily) and pyrimethamine (25 mg four times daily). The clinical features subsided within 4 days. A further check CT scan 14 days later showed almost complete resolution.

AIDS-Related Opportunistic Infections↗
PubMed1996

Transformation of Plasmodium falciparum malaria parasites by homologous integration of plasmids that confer resistance to pyrimethamine.

Plasmodium falciparum malaria parasites were transformed with plasmids containing P. falciparum or Toxoplasma gondii dihydrofolate reductase-thymidylate synthase (dhfr-ts) coding sequences that confer resistance to pyrimethamine. Under pyrimethamine pressure, transformed parasites were obtained that maintained the transfected plasmids as unrearranged episomes for several weeks. These parasite populations were replaced after 2 to 3 months by parasites that had incorporated the transfected DNA into nuclear chromosomes. Depending upon the particular construct used for transformation, homologous integration was detected in the P. falciparum dhfr-ts locus (chromosome 4) or in hrp3 and hrp2 sequences that were used in the plasmid constructs as gene control regions (chromosomes 13 and 8, respectively). Transformation by homologous integration sets the stage for targeted gene alterations and knock-outs that will advance understanding of P. falciparum.

Animals↗
PubMed1998

A biochemical and genetic model for parasite resistance to antifolates. Toxoplasma gondii provides insights into pyrimethamine and cycloguanil resistance in Plasmodium falciparum.

We have exploited the experimental accessibility of the protozoan parasite Toxoplasma gondii and its similarity to Plasmodium falciparum to investigate the influence of specific dihydrofolate reductase polymorphisms known from field isolates of drug-resistant malaria. By engineering appropriate recombinant shuttle vectors, it is feasible to examine mutations by transient or stable transformation of T. gondii parasites, in bacterial and yeast complementation assays, and through biochemical analysis of purified enzyme. A series of mutant alleles that mirror P. falciparum variants reveals that the key mutation Asn-108 (Asn-83 in T. gondii) probably confers resistance to pyrimethamine by affecting critical interactions in the ternary complex. Mutations such as Arg-59 (T. gondii 36) have limited effect in isolation, but in combination with other mutations they enhance the competitive ability of folate by increasing the speed of product turnover. Val-16 (T. gondii 10) confers low level resistance to cycloguanil but hypersensitivity to pyrimethamine. This mutation precludes Asn-108, probably because compression of the folate binding pocket introduced by this combination is incompatible with enzyme function. These studies permit detailed biochemical, kinetic, and structural analysis of drug resistance mutations and reconstruction of the probable phylogeny of antifolate resistance in malaria.

Alleles↗
PubMed1984

The chemotherapy of rodent malaria XXXV. Further studies on the retardation of drug resistance by the use of a triple combination of mefloquine, pyrimethamine and sulfadoxine in mice infected with P. berghei and 'P. berghei NS'.

In the face of an increasing prevalence of Plasmodium falciparum resistant to chloroquine and to pyrimethamine-sulphonamide or -sulphone mixtures, the need for a new, effective blood schizontocide for treatment of acute malaria is urgent. The only such compound that is almost ready for release is mefloquine (M) but there is already a danger that parasites may become resistant to this compound if it is used extensively alone. Earlier studies using a rodent model indicated that mefloquine could be 'protected' by administering it with a pyrimethamine-sulfadoxine (PS) mixture, but the experimental technique used was open to criticism. The present experiments, using a relapse technique to develop drug resistance, more closely parallel the way antimalarials are likely to be deployed in human communities. They confirm that the development of resistance to the individual components in the P. berghei N line is delayed by the triple combination, and more so in the slightly chloroquine-resistant 'P. berghei NS' line. The combination did not prevent the development of resistance in a line initially resistant to PS, but the level reached was much less than those seen when P. berghei N or 'P. berghei NS' were exposed to MPS or to M alone. It was concluded that the use of a triple combination of M, P and S against P. falciparum would be of value in 'protecting' these compounds, and thus gain time while new agents against malaria are being developed.

Animals↗