Atovaquone and proguani hydrochloride compared with chloroquine or pyrimethamine/sulfodaxine for treatment of acute Plasmodium falciparum malaria in Peru. Efficacy and safety of atovaquone/proguanil compared with mefloquine for treatment of acute Plasmodium falciparum malaria in Thailand. Atovaquone and proguanil versus pyrimethamine/sulfadoxine for the treatment of acute falciparum malaria in Zambia. Atovaquone-proguanil versus mefloquine for malaria prophylaxis in nonimmune travelers: results from a randomized, double-blind study. Atovaquone-proguanil versus chloroquine-proguanil for malaria prophylaxis in non-immune travellers: a randomised, double-blind study. Malarone International Study Team. Atovaquone and proguanil for Plasmodium falciparum malaria. Atovaquone-proguanil versus chloroquine-proguanil for malaria prophylaxis in nonimmune pediatric travelers: results of an international, randomized, open-label study. Tolerability of malaria chemoprophylaxis in non-immune travellers to sub-Saharan Africa: multicentre, randomised, double blind, four arm study. In vivo efficacy of chloroquine, halofantrine, pyrimethamine-sulfadoxine and qinghaosu (artesunate) in the treatment of malaria in Calabar, Nigeria.
The efficacy and safety of a fixed-dose combination of atovaquone and proguanil hydrochloride (Malarone) were compared with chloroquine or pyrimethamine/sulfadoxine in patients with acute falciparum malaria in northern Peru. Patients were initially randomized to receive 1,000 mg atovaquone and 400 mg proguanil hydrochloride daily for 3 days (n=15) or 1,500 mg chloroquine (base) over a 3 day period (n=14) (phase 1). The cure rate with chloroquine was lower than expected and patients were subsequently randomized to receive a single dose of 75 mg pyrimethamine and 1,500 mg sulfadoxine (n=9) or atovaquone/proguanil as before (n=5) (phase 2). In phase 1, atovaquone/proguanil was significantly more effective than chloroquine (cure rate 100% [14/14] vs. 8% [1/13], P<0.0001). In phase 2, atovaquone/proguanil and pyrimethamine/sulfadoxine were both highly effective (cure rates 100% [5/5] and 100% [7/7]). There were no significant differences between treatment groups in parasite or fever clearance times. Adverse events were typical of malarial symptoms and did not differ significantly between groups. Overall efficacy of atovaquone/proguanil was 100% for treatment of acute falciparum malaria in a region with a high prevalence of chloroquine resistance. The increasing frequency of therapeutic failures in falciparum malaria underscores the need for novel, rapidly effective antimalarial drugs or drug combinations. Atovaquone and proguanil are blood schizonticides that demonstrate synergistic activity against multi-drug-resistant Plasmodium falciparum in vitro. In an open-label, randomized, controlled clinical trial conducted in Thailand, adult patients with acute P. falciparum malaria were randomly assigned to treatment with atovaquone and proguanil/hydrochloride (1,000 mg and 400 mg, respectively, administered orally at 24-hr intervals for three doses) or mefloquine (750 mg administered orally, followed 6 hr later by an additional 500-mg dose). Efficacy was assessed by cure rate (the percentage of patients in whom parasitemia was eliminated and did not recur during 28 days of follow-up), parasite clearance time (PCT), and fever clearance time (FCT). Safety was assessed by sequential clinical and laboratory assessments for 28 days. Atovaquone/proguanil was significantly more effective than mefloquine (cure rate 100% [79 of 79] vs. 86% [68 of 79]; P < 0.002). The atovaquone/proguanil and mefloquine treatments did not differ with respect to PCT (mean = 65 hr versus 74 hr) or FCT (mean = 59 hr versus 51 hr). Adverse events were generally typical of malaria symptoms and each occurred in < 10% of the patients in either group, with the exception of increased vomiting found in the atovaquone/proguanil group. Transient elevations of liver enzyme levels occurred more frequently in patients treated with atovaquone/proguanil than with mefloquine, but the differences were not significant and values returned to normal by day 28 in most patients. The combination of atovaquone and proguanil was well tolerated and more effective than mefloquine in the treatment of acute uncomplicated multidrug-resistant falciparum malaria in Thailand. Atovaquone and proguanil hydrochloride are blood schizonticides that demonstrate in vitro synergy against drug-resistant strains of Plasmodium falciparum. When coadministered, they may therefore be effective for the treatment of malaria in regions where there is known or suspected drug resistance. In an open-label, randomized, parallel-group, clinical trial conducted in Zambia, 163 patients (age range, 14 to 54 years) with acute P falciparum malaria were randomly assigned to receive treatment with atovaquone and proguanil hydrochloride (1000 and 400 mg, respectively, administered orally at 24-hour intervals for 3 doses; n = 82) or pyrimethamine/sulfadoxine (75/1500 mg administered orally as a single dose; n = 81). Efficacy was assessed by cure rate (the percentage of patients in whom parasitemia was eliminated and did not recur during 28 days of follow-up), parasite clearance time (PCT), and fever clearance time (FCT). Safety was determined by sequential clinical and laboratory assessments over 28 days. Cure rates did not differ significantly between patients treated with atovaquone and proguanil (100%) and those treated with pyrimethamine/sulfadoxine (98.8%). Patients in the atovaquone and proguanil group had a significantly shorter FCT than patients in the pyrimethamine/sulfadoxine group (mean, 30.4 vs 44.9 hours; P < 0.05) but a longer PCT (mean, 64.0 vs 51.4 hours; P < 0.05). Both treatments were well tolerated; adverse events and laboratory abnormalities were typical of those normally observed in patients with malaria. In this study, the combination of atovaquone and proguanil was equally effective and as well tolerated as pyrimethamine/sulfadoxine for the treatment of acute, uncomplicated, drug-resistant falciparum malaria in Zambia. Concerns about the tolerability of mefloquine highlight the need for new drugs to prevent malaria. Atovaquone-proguanil (Malarone; GlaxoSmithKline) was safe and effective for prevention of falciparum malaria in lifelong residents of malaria-endemic countries, but experience in nonimmune people is limited. In a randomized, double-blind study, nonimmune travelers received malaria prophylaxis with atovaquone-proguanil (493 subjects) or mefloquine (483 subjects). Information about adverse events (AEs) and potential episodes of malaria was obtained 7, 28, and 60 days after travel. AEs were reported by an equivalent proportion of subjects who had received atovaquone-proguanil or mefloquine (71.4% versus 67.3%; difference, 4.1%; 95% confidence interval, -1.71 to 9.9). Subjects who received atovaquone-proguanil had fewer treatment-related neuropsychiatric AEs (14% versus 29%; P=.001), fewer AEs of moderate or severe intensity (10% versus 19%; P=.001), and fewer AEs that caused prophylaxis to be discontinued (1.2% versus 5.0%; P=.001), compared with subjects who received melfoquine. No confirmed diagnoses of malaria occurred in either group. Atovaquone-proguanil was better tolerated than was mefloquine, and it was similarly effective for malaria prophylaxis in nonimmune travelers. Chloroquine plus proguanil is widely used for malaria chemoprophylaxis despite low effectiveness in areas where multidrug-resistant malaria occurs. Studies have shown that atovaquone and proguanil hydrochloride is safe and effective for prevention of falciparum malaria in lifelong residents of malaria-endemic countries, but little is known about non-immune travellers.
                In a double-blind equivalence trial, 1083 participants travelling to a malaria-endemic area were randomly assigned to two treatment groups: atovaquone-proguanil plus placebos for chloroquine and proguanil, or chloroquine, proguanil, and placebo for atovaquone-proguanil. Follow-up was by telephone 7 and 60 days after travel and at a clinic at 28 days. Serum samples were tested for antibodies to a malaria circumsporozoite protein. Blood and serum samples of participants with a potential malaria diagnosis were tested in a reference laboratory.
                7 days after travel, at least one adverse event was reported by 311 (61%) of 511 participants who received atovaquone-proguanil and 329 (64%) of 511 who received chloroquine-proguanil. People receiving atovaquone-proguanil had a lower frequency of treatment-related gastrointestinal adverse events (59 [12%] vs 100 [20%], p=0.001), and of treatment-related adverse events of moderate or severe intensity (37 [7%] vs 56 [11%], p=0.05). There were fewer treatment-related adverse events that caused prophylaxis to be discontinued in the atovaquone-proguanil group than in the chloroquine-proguanil group (one [0.2%] vs ten [2%], p=0.015).
                Overall the two preparations were similarly tolerated. However, significantly fewer adverse gastrointestinal events were observed in the atovaquone-proguanil group in than in the chloroquine-proguanil group. The increasing spread of multidrug-resistant Plasmodium falciparum malaria emphasises the urgent need for alternative treatment regimens. The objective of the study was to establish the efficacy of a novel drug combination. We compared a combination of atovaquone and proguanil with amodiaquine in the treatment of acute uncomplicated P falciparum malaria in Lambaréné, Gabon.
                142 adults were randomly allocated either a combination treatment of atovaquone 1000 mg daily and proguanil 400 mg daily for 3 days or treatment with amodiaquine 600 mg on admission, 600 mg 24 h later, and 300 mg after a further 24 h. Symptoms and clinical signs were recorded and giemsa-stained thick blood smears were done every 12 h until patients had been symptom-free and aparasitaemic for 24 h. 126 patients were followed up for 28 days or until recrudescence.
                In the atovaquone plus proguanil group 62 (87%) of 71 patients were cured and only one had recrudescent infection. By contrast, the cure rate was significantly lower (p=0.022) with amodiaquine (51 [72%] of 71; there were 12 recrudescences in the amodiaquine group). Eight patients in each group were lost to follow-up. Patients treated with atovaquone plus proguanil complained of nausea (33%) and vomiting (29%), and the most commonly reported adverse effects of amodiaquine were pruritus (43%) and insomnia (27%).
                Atovaquone and proguanil was a highly effective and safe drug combination in patients with acute uncomplicated P falciparum malaria in Gabon. Atovaquone-proguanil has been shown to be effective and well tolerated for malaria prophylaxis in residents of countries of endemicity and in nonimmune adult travelers, but data about traveling children are limited. In a randomized, open-label, multicenter prophylaxis trial, 221 nonimmune pediatric travelers (age, 2-17 years) received either atovaquone-proguanil or chloroquine-proguanil. Safety and clinical outcome were evaluated 7, 28, and 60 days after travel. By posttravel day 7, a total of 39 (35%) of 110 atovaquone-proguanil and 41 (37%) of 111 chloroquine-proguanil recipients reported > or =1 adverse event. The data indicate that, over the course of treatment, fewer atovaquone-proguanil recipients had treatment-related adverse events (8% vs. 14%), including gastrointestinal complaints (5% vs. 10%). Two subjects discontinued prophylaxis because of drug-related adverse events; both had received chloroquine-proguanil. Observed compliance with prophylaxis was similar before and during travel, but it was higher for atovaquone-proguanil in the posttravel period. No study participant developed malaria. Atovaquone-proguanil was well tolerated and is an important addition to the limited arsenal of prophylactic agents available to children. To compare the tolerability of malaria chemoprophylaxis regimens in non-immune travellers.
                Randomised, double blind, study with placebo run-in phase.
                Travel clinics in Switzerland, Germany, and Israel.
                Proportion of participants in each treatment arm with subjectively moderate or severe adverse events.
                623 non-immune travellers to sub-Saharan Africa: 153 each received either doxycycline, mefloquine, or the fixed combination chloroquine and proguanil, and 164 received the fixed combination atovaquone and proguanil.
                A high proportion of patients reported adverse events, even in the initial placebo group. No events were serious. The chloroquine and proguanil arm had the highest proportion of mild to moderate adverse events (69/153; 45%, 95% confidence interval 37% to 53%), followed by mefloquine (64/153; 42%, 34% to 50%), doxycycline (51/153; 33%, 26% to 41%), and atovaquone and proguanil (53/164; 32%, 25% to 40%) (P = 0.048 for all). The mefloquine and combined chloroquine and proguanil arms had the highest proportion of more severe events (n = 19; 12%, 7% to 18% and n = 16; 11%, 6% to 15%, respectively), whereas the combined atovaquone and proguanil and doxycycline arms had the lowest (n = 11; 7%, 2% to 11% and n = 9; 6%, 2% to 10%, respectively: P = 0.137 for all). The mefloquine arm had the highest proportion of moderate to severe neuropsychological adverse events, particularly in women (n = 56; 37%, 29% to 44% versus chloroquine and proguanil, n = 46; 30%, 23% to 37%; doxycycline, n = 36; 24%, 17% to 30%; and atovaquone and proguanil, n = 32; 20%, 13% to 26%: P = 0.003 for all). The highest proportion of moderate or severe skin problems were reported in the chloroquine and proguanil arm (n = 12; 8%, 4% to 13% versus doxycycline, n = 5; 3%, 1% to 6%; atovaquone and proguanil, n = 4; 2%, 0% to 5%; mefloquine, n = 2; 1%, 0% to 3%: P = 0.013).
                Combined atovaquone and proguanil and doxycyline are well tolerated antimalarial drugs. Broader experience with both agents is needed to accumulate reports of rare adverse events. We used the WHO in vivo seven day test, extended to 14 day follow up to evaluate the efficacy of the alternative antimalarial drugs in Nigeria (1992), where chloroquine resistant P. falciparum (CRPD) has been confirmed. One thousand and four patients were screened. Those fulfilling recruitment criteria were randomly treated with chloroquine (CQ), n = 50, halofantrine (H), n = 53, pyrimethamine-sulfadoxine (P-S), n = 52 and qinghaosu (Q), n = 53. Parasitological treatment failures were found with all drugs i.e. CQ-53.6pc, H-9.5pc, P-S-28.5pc and Q-2.0pc. H and Q were significantly more efficacious than CQ and P-S, p < 0.003 and p < 0.006, respectively. similarly symptom clearance after 48 hours by H and Q, was 76.3pc and 94pc respectively, better than CQ. P-S was not significantly better than CQ, 64.4pc and 63.3pc, respectively, p > 0.05. The symptom clearance rate of CQ has markedly reduced from 97.7pc to 67.7pc, and in increased proportion of RIII, from 5.9pc to 14.3pc, are signs of increase in chloroquine resistant Plasmodium falciparum. Drug resistant P. falciparum in Nigeria constitutes a serious problem to malaria chemotherapy.
Data are limited but appear to suggest that atovaquone-proguanil is more effective than chloroquine, amodiaquine, and mefloquine. There are insufficient data for comparisons against sulfadoxine-pyrimethamine, halofantrine, artesunate plus mefloquine, quinine plus tetracycline, and dihydroartemisinin-piperaquine-trimethoprim-primaquine in treating malaria. There are not enough data to assess safety, but a number of adverse events were identified with all drugs. Large trials comparing atovaquone-proguanil with other new combination therapies are needed.