Adults

One atovaquone and proguanil hydrochloride tablet (adult strength = 250 mg atovaquone/100 mg proguanil hydrochloride) per day.

Pediatric Patients

The dosage for prevention of malaria in pediatric patients is based upon body weight (Table 1).

Adults

Four atovaquone and proguanil hydrochloride tablets (adult strength; total daily dose 1 g atovaquone/400 mg proguanil hydrochloride) as a single daily dose for 3 consecutive days.

Pediatric Patients

The dosage for treatment of acute malaria in pediatric patients is based upon body weight (Table 2).

Prophylaxis of P.falciparum Malaria

In 3 clinical trials (2 of which were placebo-controlled) 381 adults (mean age: 31 years) received atovaquone and proguanil hydrochloride tablets for the prophylaxis of malaria; the majority of adults were black (90%) and 79% were male. In a clinical trial for the prophylaxis of malaria, 125 pediatric patients (mean age: 9 years) received atovaquone and proguanil hydrochloride tablets; all subjects were black and 52% were male. Adverse experiences reported in adults and pediatric patients considered attributable to therapy occurred in similar proportions of subjects receiving atovaquone and proguanil hydrochloride tablets or placebo in all studies. Prophylaxis with atovaquone and proguanil hydrochloride tablets was discontinued prematurely due to a treatment-related adverse experience in 3 of 381 (0.8%) adults and 0 of 125 pediatric patients.

In a placebo-controlled study of malaria prophylaxis with atovaquone and proguanil hydrochloride tablets involving 330 pediatric patients (aged 4 to 14 years) in Gabon, a malaria-endemic area, the safety profile of atovaquone and proguanil hydrochloride tablets was consistent with that observed in the earlier prophylactic studies in adults and pediatric patients. The most common treatment-emergent adverse events with atovaquone and proguanil hydrochloride tablets were abdominal pain (13%), headache (13%), and cough (10%). Abdominal pain (13% vs. 8%) and vomiting (5% vs. 3%) were reported more often with atovaquone and proguanil hydrochloride tablets than with placebo. No patient withdrew from the study due to an adverse experience with atovaquone and proguanil hydrochloride tablets. No routine laboratory data were obtained during this study.

Non-immune travelers visiting a malaria-endemic area received atovaquone and proguanil hydrochloride tablets (n = 1,004) for prophylaxis of malaria in 2 active-controlled clinical trials. In one study (n = 493), the mean age of subjects was 33 years and 53% were male; 90% of subjects were white, 6% of subjects were black, and the remaining were of other racial/ethnic groups. In the other study (n = 511), the mean age of subjects was 36 years and 51% were female; the majority of subjects (97%) were white. Adverse experiences occurred in a similar or lower proportion of subjects receiving atovaquone and proguanil hydrochloride tablets than an active comparator (Table 3). Fewer neuropsychiatric adverse experiences occurred in subjects who received atovaquone and proguanil hydrochloride tablets than mefloquine. Fewer gastrointestinal adverse experiences occurred in subjects receiving atovaquone and proguanil hydrochloride tablets than chloroquine/proguanil. Compared with active comparator drugs, subjects receiving atovaquone and proguanil hydrochloride tablets had fewer adverse experiences overall that were attributed to prophylactic therapy (Table 3). Prophylaxis with atovaquone and proguanil hydrochloride tablets was discontinued prematurely due to a treatment-related adverse experience in 7 of 1,004 travelers.

Table 3. Adverse Experiences in Active-Controlled Clinical Trials of Atovaquone and Proguanil Hydrochloride Tablets for Prophylaxis of P. falciparum Malaria

In a third active-controlled study, atovaquone and proguanil hydrochloride tablets (n = 110) was compared with chloroquine/proguanil (n = 111) for the prophylaxis of malaria in 221 non-immune pediatric patients (aged 2 to 17 years). The mean duration of exposure was 23 days for atovaquone and proguanil hydrochloride tablets, 46 days for chloroquine, and 43 days for proguanil, reflecting the different recommended dosage regimens for these products. Fewer patients treated with atovaquone and proguanil hydrochloride tablets reported abdominal pain (2% vs. 7%) or nausea (< 1% vs. 7%) than children who received chloroquine/proguanil. Oral ulceration (2% vs. 2%), vivid dreams (2% vs. < 1%), and blurred vision (0% vs. 2%) occurred in similar proportions of patients receiving either atovaquone and proguanil hydrochloride tablets or chloroquine/proguanil, respectively. Two patients discontinued prophylaxis with chloroquine/proguanil due to adverse events, while none of those receiving atovaquone and proguanil hydrochloride tablets discontinued due to adverse events.

Treatment of Acute, Uncomplicated P. falciparum Malaria

In 7 controlled trials, 436 adolescents and adults received atovaquone and proguanil hydrochloride tablets for treatment of acute, uncomplicated P. falciparum malaria. The range of mean ages of subjects was 26 to 29 years; 79% of subjects were male. In these studies, 48% of subjects were classified as other racial/ethnic groups, primarily Asian; 42% of subjects were black and the remaining subjects were white. Attributable adverse experiences that occurred in ≥ 5% of patients were abdominal pain (17%), nausea (12%), vomiting (12%), headache (10%), diarrhea (8%), asthenia (8%), anorexia (5%), and dizziness (5%). Treatment was discontinued prematurely due to an adverse experience in 4 of 436 (0.9%) adolescents and adults treated with atovaquone and proguanil hydrochloride tablets.

In 2 controlled trials, 116 pediatric patients (weighing 11 to 40 kg) (mean age: 7 years) received atovaquone and proguanil hydrochloride tablets for the treatment of malaria. The majority of subjects were black (72%); 28% were of other racial/ethnic groups, primarily Asian. Attributable adverse experiences that occurred in ≥ 5% of patients were vomiting (10%) and pruritus (6%). Vomiting occurred in 43 of 319 (13%) pediatric patients who did not have symptomatic malaria but were given treatment doses of atovaquone and proguanil hydrochloride tablets for 3 days in a clinical trial. The design of this clinical trial required that any patient who vomited be withdrawn from the trial. Among pediatric patients with symptomatic malaria treated with atovaquone and proguanil hydrochloride tablets, treatment was discontinued prematurely due to an adverse experience in 1 of 116 (0.9%).

In a study of 100 pediatric patients (5 to < 11 kg body weight) who received atovaquone and proguanil hydrochloride tablets for the treatment of uncomplicated P. falciparum malaria, only diarrhea (6%) occurred in ≥ 5% of patients as an adverse experience attributable to atovaquone and proguanil hydrochloride tablets. In 3 patients (3%), treatment was discontinued prematurely due to an adverse experience.

Abnormalities in laboratory tests reported in clinical trials were limited to elevations of transaminases in patients with malaria being treated with atovaquone and proguanil hydrochloride tablets. The frequency of these abnormalities varied substantially across trials of treatment and were not observed in the randomized portions of the prophylaxis trials.

One active-controlled trial evaluated the treatment of malaria in Thai adults (n = 182); the mean age of subjects was 26 years (range: 15 to 63 years); 80% of subjects were male. Early elevations of ALT and AST occurred more frequently in patients treated with atovaquone and proguanil hydrochloride tablets (n = 91) compared with patients treated with an active control, mefloquine (n = 91). On Day 7, rates of elevated ALT and AST with atovaquone and proguanil hydrochloride tablets and mefloquine (for patients who had normal baseline levels of these clinical laboratory parameters) were ALT 26.7% vs. 15.6%; AST 16.9% vs. 8.6%, respectively. By Day 14 of this 28-day study, the frequency of transaminase elevations equalized across the 2 groups.

Risk Summary

Available data from published literature and postmarketing experience with use of atovaquone and proguanil hydrochloride tablets in pregnant women are insufficient to identify a drug-associated risk for major birth defects, miscarriage, or adverse maternal or fetal outcomes. The proguanil component of atovaquone and proguanil hydrochloride tablets acts to inhibit parasitic dihydrofolate reductase; however, pregnant women and females of reproductive potential should continue folate supplementation to prevent neural tube defects [see Clinical Pharmacology (12.4)]. Pregnant women with malaria are at increased risk for adverse pregnancy outcomes (see Clinical Considerations).

Atovaquone administered by oral gavage to pregnant rats and rabbits during the period of organogenesis was not associated with fetal malformations at plasma exposures approximately 7 times and equal to, respectively, the estimated human exposure for the treatment of malaria based on AUC. Proguanil administered to pregnant rats and rabbits during the period of organogenesis was not associated with embryo-fetal toxicity at maternally toxic plasma exposures approximately 0.07 and 0.8 times, respectively, the estimated human exposure for treatment of malaria based on AUC (see Data).

The combination of atovaquone and proguanil hydrochloride given orally by gavage during the period of organogenesis was not associated with embryo-fetal developmental effects in pregnant rats or rabbits at atovaquone:proguanil hydrochloride doses of 50:20 mg/kg/day and 100:40 mg/kg/day, respectively (1.7 and 0.1 times and 0.3 and 0.5 times, respectively, the estimated human exposure for treatment of malaria). In a pre- and post-natal study with atovaquone and another pre- and post-natal study with proguanil, neither compound impaired the growth, development, or reproductive ability of first generation offspring at maternal AUC exposures of approximately 7.3 and 0.04 times, respectively, the estimated human AUC exposure for treatment of malaria (see Data).

The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively.

Clinical Considerations

Data

Risk Summary

There are no data on the presence of atovaquone in human milk; however, proguanil is present in human milk. Atovaquone is present in rat milk (see Data). When a drug is present in animal milk, it is likely the drug will be present in human milk. There are no data on the effects of atovaquone and proguanil on the breastfed child or the effects on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for atovaquone and proguanil hydrochloride tablets and any potential adverse effect on the breastfed child from atovaquone and proguanil or from the underlying maternal condition.

Data

In a rat study with doses of 10 and 250 mg/kg, given orally by gavage on postpartum Day 11, atovaquone concentrations in the milk were 30% of the concurrent atovaquone concentrations in the maternal plasma at both doses. The concentration of drug in animal milk does not necessarily predict the concentration of drug in human milk.

Prophylaxis of Malaria

Safety and effectiveness have not been established in pediatric patients who weigh less than 11 kg. The efficacy and safety of atovaquone and proguanil hydrochloride tablets have been established for the prophylaxis of malaria in controlled trials involving pediatric patients weighing 11 kg or more [see Clinical Studies (14.1)].

Treatment of Malaria

Safety and effectiveness have not been established in pediatric patients who weigh less than 5 kg. The efficacy and safety of atovaquone and proguanil hydrochloride tablets for the treatment of malaria have been established in controlled trials involving pediatric patients weighing 5 kg or more [see Clinical Studies (14.2)].

Cardiac Effects

The effect of atovaquone and proguanil hydrochloride tablets on the QT interval is unknown in humans.

Absorption

Atovaquone is a highly lipophilic compound with low aqueous solubility. The bioavailability of atovaquone shows considerable inter-individual variability.

Distribution

Atovaquone is highly protein bound (> 99%) over the concentration range of 1 to 90 mcg/mL. A population pharmacokinetic analysis demonstrated that the apparent volume of distribution of atovaquone (V/F) in adult and pediatric patients after oral administration is approximately 8.8 L/kg.

Proguanil is 75% protein bound. A population pharmacokinetic analysis demonstrated that the apparent V/F of proguanil in adult and pediatric patients older than 15 years with body weights from 31 to 110 kg ranged from 1,617 to 2,502 L. In pediatric patients 15 years and younger with body weights from 11 to 56 kg, the V/F of proguanil ranged from 462 to 966 L.

In human plasma, the binding of atovaquone and proguanil was unaffected by the presence of the other.

Elimination

The elimination half-life of atovaquone is about 2 to 3 days in adult patients. The elimination half-life of proguanil is 12 to 21 hours in both adult patients and pediatric patients, but may be longer in individuals who are slow metabolizers.

The main routes of elimination are hepatic biotransformation and renal excretion.

Special Populations

Drug Interaction Studies

There are no pharmacokinetic interactions between atovaquone and proguanil at the recommended dose.

Atovaquone is highly protein bound (> 99%) but does not displace other highly protein-bound drugs in vitro.

Proguanil is metabolized primarily by CYP2C19. Potential pharmacokinetic interactions between proguanil or cycloguanil and other drugs that are CYP2C19 substrates or inhibitors are unknown.

Mechanism of Action

The constituents of atovaquone and proguanil hydrochloride tablets, atovaquone and proguanil hydrochloride, interfere with 2 different pathways involved in the biosynthesis of pyrimidines required for nucleic acid replication. Atovaquone is a selective inhibitor of parasite mitochondrial electron transport. Proguanil hydrochloride primarily exerts its effect by means of the metabolite cycloguanil, a dihydrofolate reductase inhibitor. Inhibition of dihydrofolate reductase in the Plasmodium parasite disrupts deoxythymidylate synthesis.

Antimicrobial Activity

Atovaquone and cycloguanil (an active metabolite of proguanil) are active against the erythrocytic and exoerythrocytic stages of P. falciparum. Enhanced efficacy of the combination compared with either atovaquone or proguanil hydrochloride alone was demonstrated in clinical trials in both immune and non-immune patients [see Clinical Studies (14.1, 14.2)].

Resistance

Strains of P. falciparum with decreased susceptibility to atovaquone or proguanil/cycloguanil alone can be selected in vitro or in vivo. The combination of atovaquone and proguanil hydrochloride may not be effective for treatment of recrudescent malaria that develops after prior therapy with the combination.

Atovaquone

A 24-month carcinogenicity study in CD rats was negative for neoplasms at doses up to 500 mg/kg/day corresponding to approximately 54 times the average steady-state plasma concentrations in humans during prophylaxis of malaria. In CD-1 mice, a 24-month study showed treatment-related increases in incidence of hepatocellular adenoma and hepatocellular carcinoma at all doses tested (50, 100, and 200 mg/kg/day) which correlated with at least 15 times the average steady-state plasma concentrations in humans during prophylaxis of malaria.

Atovaquone was negative with or without metabolic activation in the Ames Salmonella mutagenicity assay, the mouse lymphoma mutagenesis assay, and the cultured human lymphocyte cytogenetic assay. No evidence of genotoxicity was observed in the in vivo mouse micronucleus assay.

Atovaquone administered by oral gavage in doses of 100, 300, or 1,000 mg/kg/day to adult male rats from 73 days prior to mating until 20 days after mating and to adult female rats from 14 days prior to mating until LD20 did not impair male or female fertility or early embryonic development at doses up to 1,000 mg/kg/day corresponding to plasma exposures of approximately 7.3 times the estimated human exposure for the treatment of malaria based on AUC.

Proguanil

No evidence of a carcinogenic effect was observed in 24-month studies conducted in CD-1 mice at doses up to 16 mg/kg/day corresponding to 1.5 times the average human plasma exposure during prophylaxis of malaria based on AUC, and in Wistar Hannover rats at doses up 20 mg/kg/day corresponding to 1.1 times the average human plasma exposure during prophylaxis of malaria based on AUC.

Proguanil was negative with or without metabolic activation in the Ames Salmonella mutagenicity assay and the mouse lymphoma mutagenesis assay. No evidence of genotoxicity was observed in the in vivo mouse micronucleus assay.

Cycloguanil, the active metabolite of proguanil, was also negative in the Ames test, but was positive in the mouse lymphoma assay and the mouse micronucleus assay. These positive effects with cycloguanil, a dihydrofolate reductase inhibitor, were significantly reduced or abolished with folinic acid supplementation.

Proguanil administered orally in doses of 4, 8, and 16 mg/kg/day to male rats from 29 days prior to mating until 27 days after mating and to females from 15 days prior to mating through GD7 revealed no adverse effects on adult male or female fertility or early embryonic development at doses up to 16 mg/kg/day (up to 0.04 times the average human exposure for the treatment of malaria based on AUC). Fertility studies of proguanil in animals at exposures similar to or greater than those observed in humans have not been conducted.

Causal Prophylaxis

In separate trials with small numbers of volunteers, atovaquone and proguanil hydrochloride were independently shown to have causal prophylactic activity directed against liver-stage parasites of P. falciparum. Six patients given a single dose of atovaquone 250 mg 24 hours prior to malaria challenge were protected from developing malaria, whereas all 4 placebo-treated patients developed malaria.

During the 4 weeks following cessation of prophylaxis in clinical trial participants who remained in malaria-endemic areas and were available for evaluation, malaria developed in 24 of 211 (11.4%) subjects who took placebo and 9 of 328 (2.7%) who took atovaquone and proguanil hydrochloride tablets. While new infections could not be distinguished from recrudescent infections, all but 1 of the infections in patients treated with atovaquone and proguanil hydrochloride tablets occurred more than 15 days after stopping therapy. The single case occurring on Day 8 following cessation of therapy with atovaquone and proguanil hydrochloride tablets probably represents a failure of prophylaxis with atovaquone and proguanil hydrochloride tablets.

The possibility that delayed cases of P. falciparum malaria may occur sometime after stopping prophylaxis with atovaquone and proguanil hydrochloride tablets cannot be ruled out. Hence, returning travelers developing febrile illnesses should be investigated for malaria.