Malaria treatment failures after artemisinin-based therapy in three expatriates: could improved manufacturer information help to decrease the risk of treatment failure ?

BACKGROUND: Artemisinin-containing therapies are highly effective against Plasmodium falciparum malaria. Insufficient numbers of tablets and inadequate package inserts result in sub-optimal dosing and possible treatment failure. This study reports the case of three, non-immune, expatriate workers with P. falciparum acquired in Africa, who failed to respond to artemisinin-based therapy. Sub-therapeutic dosing in accordance with the manufacturers' recommendations was the probable cause. METHOD: Manufacturers information and drug content included in twenty-five artemisinin-containing specialities were reviewed. RESULTS: A substantial number of manufacturers do not follow current WHO recommendations regarding treatment duration and doses. CONCLUSION: This study shows that drug packaging and their inserts should be improved

Failure of artesunate-mefloquine combination therapy for uncomplicated Plasmodium falciparum malaria in southern Cambodia

<p>Abstract</p> <p>Background</p> <p>Resistance to anti-malarial drugs hampers control efforts and increases the risk of morbidity and mortality from malaria. The efficacy of standard therapies for uncomplicated <it>Plasmodium falciparum </it>and <it>Plasmodium vivax </it>malaria was assessed in Chumkiri, Kampot Province, Cambodia.</p> <p>Methods</p> <p>One hundred fifty-one subjects with uncomplicated falciparum malaria received directly observed therapy with 12 mg/kg artesunate (over three days) and 25 mg/kg mefloquine, up to a maximum dose of 600 mg artesunate/1,000 mg mefloquine. One hundred nine subjects with uncomplicated vivax malaria received a total of 25 mg/kg chloroquine, up to a maximum dose of 1,500 mg, over three days. Subjects were followed for 42 days or until recurrent parasitaemia was observed. For <it>P. falciparum </it>infected subjects, PCR genotyping of <it>msp1</it>, <it>msp2</it>, and <it>glurp </it>was used to distinguish treatment failures from new infections. Treatment failure rates at days 28 and 42 were analyzed using both per protocol and Kaplan-Meier survival analysis. Real Time PCR was used to measure the copy number of the <it>pfmdr1 </it>gene and standard 48-hour isotopic hypoxanthine incorporation assays were used to measure IC₅₀for anti-malarial drugs.</p> <p>Results</p> <p>Among <it>P. falciparum </it>infected subjects, 47.0% were still parasitemic on day 2 and 11.3% on day 3. The PCR corrected treatment failure rates determined by survival analysis at 28 and 42 days were 13.1% and 18.8%, respectively. Treatment failure was associated with increased <it>pfmdr1 </it>copy number, higher initial parasitaemia, higher mefloquine IC₅₀, and longer time to parasite clearance. One <it>P. falciparum </it>isolate, from a treatment failure, had markedly elevated IC₅₀for both mefloquine (130 nM) and artesunate (6.7 nM). Among <it>P. vivax </it>infected subjects, 42.1% suffered recurrent <it>P. vivax </it>parasitaemia. None acquired new <it>P. falciparum </it>infection.</p> <p>Conclusion</p> <p>The results suggest that artesunate-mefloquine combination therapy is beginning to fail in southern Cambodia and that resistance is not confined to the provinces at the Thai-Cambodian border. It is unclear whether the treatment failures are due solely to mefloquine resistance or to artesunate resistance as well. The findings of delayed clearance times and elevated artesunate IC₅₀suggest that artesunate resistance may be emerging on a background of mefloquine resistance.</p

Rectal artemisinins for malaria: a review of efficacy and safety from individual patient data in clinical studies

<p>Abstract</p> <p>Background</p> <p>Rectal administration of artemisinin derivatives has potential for early treatment for severe malaria in remote settings where injectable antimalarial therapy may not be feasible. Preparations available include artesunate, artemisinin, artemether and dihydroartemisinin. However each may have different pharmacokinetic properties and more information is needed to determine optimal dose and comparative efficacy with each another and with conventional parenteral treatments for severe malaria.</p> <p>Methods</p> <p>Individual patient data from 1167 patients in 15 clinical trials of rectal artemisinin derivative therapy (artesunate, artemisinin and artemether) were pooled in order to compare the rapidity of clearance of <it>Plasmodium falciparum </it>parasitaemia and the incidence of reported adverse events with each treatment. Data from patients who received comparator treatment (parenteral artemisinin derivative or quinine) were also included. Primary endpoints included percentage reductions in parasitaemia at 12 and 24 hours. A parasite reduction of >90% at 24 hours was defined as parasitological success.</p> <p>Results</p> <p>Artemisinin and artesunate treatment cleared parasites more rapidly than parenteral quinine during the first 24 hours of treatment. A single higher dose of rectal artesunate treatment was five times more likely to achieve >90% parasite reductions at 24 hours than were multiple lower doses of rectal artesunate, or a single lower dose administration of rectal artemether.</p> <p>Conclusion</p> <p>Artemisinin and artesunate suppositories rapidly eliminate parasites and appear to be safe. There are less data on artemether and dihydroartemisinin suppositories. The more rapid parasite clearance of single high-dose regimens suggests that achieving immediate high drug concentrations may be the optimal strategy.</p