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General

MALARONE (atovaquone and proguanil hcl) has not been evaluated for the treatment of cerebral malaria or other severe manifestations of complicated malaria, including hyperparasitemia, pulmonary edema, or renal failure. Patients with severe malaria are not candidates for oral therapy.

Elevated liver function tests and rare cases of hepatitis have been reported with prophylactic use of MALARONE (atovaquone and proguanil hcl) . A single case of hepatic failure requiring liver transplantation has also been reported with prophylactic use.

Absorption of atovaquone may be reduced in patients with diarrhea or vomiting. If MALARONE is used in patients who are vomiting (see DOSAGE AND ADMINISTRATION), parasitemia should be closely monitored and the use of an antiemetic considered. Vomiting occurred in up to 19% of pediatric patients given treatment doses of MALARONE (atovaquone and proguanil hcl) . In the controlled clinical trials of MALARONE (atovaquone and proguanil hcl) , 15.3% of adults who were treated with atovaquone/proguanil received an antiemetic drug during that part of the trial when they received atovaquone/proguanil. Of these patients, 98.3% were successfully treated. In patients with severe or persistent diarrhea or vomiting, alternative antimalarial therapy may be required.

Parasite relapse occurred commonly when P. vivax malaria was treated with MALARONE (atovaquone and proguanil hcl) alone.

In the event of recrudescent P. falciparum infections after treatment with MALARONE (atovaquone and proguanil hcl) or failure of chemoprophylaxis with MALARONE (atovaquone and proguanil hcl) , patients should be treated with a different blood schizonticide.

Carcinogenesis, Mutagenesis, Impairment of Fertility

Atovaquone: Carcinogenicity studies in rats were negative; 24-month studies in mice showed treatment-related increases in incidence of hepatocellular adenoma and hepatocellular carcinoma at all doses tested which ranged from approximately 5 to 8 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.

Proguanil: No evidence of a carcinogenic effect was observed in 24-month studies conducted in CD-1 mice (doses up to 1.5 times the average systemic human exposure based on AUC) and in Wistar Hannover rats (doses up to 1.1 times the average systemic human exposure).

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.

A fertility study in Sprague-Dawley rats revealed no adverse effects at doses up to 16 mg/kg/day of proguanil hydrochloride (up to 0.2-times the average human exposure based on AUC comparisons.) Fertility studies of proguanil in animals at exposures similar to or greater than those observed in humans have not been conducted.

Genotoxicity studies have not been performed with atovaquone in combination with proguanil. Effects of MALARONE (atovaquone and proguanil hcl) on male and female reproductive performance are unknown.

Pregnancy

Pregnancy Category C. Falciparum malaria carries a higher risk of morbidity and mortality in pregnant women than in the general population. Maternal death and fetal loss are both known complications of falciparum malaria in pregnancy. In pregnant women who must travel to malaria-endemic areas, personal protection against mosquito bites should always be employed (see Information for Patients) in addition to antimalarials.

Atovaquone was not teratogenic and did not cause reproductive toxicity in rats at maternal plasma concentrations up to 5 to 6.5 times the estimated human exposure during treatment of malaria. Following single-dose administration of ¹⁴C-labeled atovaquone to pregnant rats, concentrations of radiolabel in rat fetuses were 18% (mid-gestation) and 60% (late gestation) of concurrent maternal plasma concentrations. In rabbits, atovaquone caused maternal toxicity at plasma concentrations that were approximately 0.6 to 1.3 times the estimated human exposure during treatment of malaria. Adverse fetal effects in rabbits, including decreased fetal body lengths and increased early resorptions and post-implantation losses, were observed only in the presence of maternal toxicity. Concentrations of atovaquone in rabbit fetuses averaged 30% of the concurrent maternal plasma concentrations.

A pre- and post-natal study in Sprague-Dawley rats revealed no adverse effects at doses up to 16 mg/kg/day of proguanil hydrochloride (up to 0.2-times the average human exposure based on AUC comparisons). Pre- and post-natal studies of proguanil in animals at exposures similar to or greater than those observed in humans have not been conducted.

The combination of atovaquone and proguanil hydrochloride was not teratogenic in rats at plasma concentrations up to 1.7 and 0.10 times, respectively, the estimated human exposure during treatment of malaria. In rabbits, the combination of atovaquone and proguanil hydrochloride was not teratogenic or embryotoxic to rabbit fetuses at plasma concentrations up to 0.34 and 0.82 times, respectively, the estimated human exposure during treatment of malaria.

While there are no adequate and well-controlled studies of atovaquone and/or proguanil hydrochloride in pregnant women, MALARONE (atovaquone and proguanil hcl) may be used if the potential benefit justifies the potential risk to the fetus. The proguanil component of MALARONE (atovaquone and proguanil hcl) acts by inhibiting the parasitic dihydrofolate reductase (see CLINICAL PHARMACOLOGY: Microbiology: Mechanism of Action). However, there are no clinical data indicating that folate supplementation diminishes drug efficacy, and for women of childbearing age receiving folate supplements to prevent neural tube birth defects, such supplements may be continued while taking MALARONE (atovaquone and proguanil hcl) .

Nursing Mothers

It is not known whether atovaquone is excreted into human milk. In a rat study, atovaquone concentrations in the milk were 30% of the concurrent atovaquone concentrations in the maternal plasma.

Proguanil is excreted into human milk in small quantities.

Caution should be exercised when MALARONE (atovaquone and proguanil hcl) is administered to a nursing woman.

Pediatric Use

Treatment of Malaria: The efficacy and safety of MALARONE (atovaquone and proguanil hcl) for the treatment of malaria have been established in controlled studies involving pediatric patients weighing 5 kg or more (see Clinical Studies). Safety and effectiveness have not been established in pediatric patients who weigh less than 5 kg.

Prophylaxis of Malaria: The efficacy and safety of MALARONE (atovaquone and proguanil hcl) have been established for the prophylaxis of malaria in controlled studies involving pediatric patients weighing 11 kg or more (see Clinical Studies). Safety and effectiveness have not been established in pediatric patients who weigh less than 11 kg.

Geriatric Use

Clinical studies of MALARONE (atovaquone and proguanil hcl) did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. In general, dose selection for an elderly patient should be cautious, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, the higher systemic exposure to cycloguanil (see CLINICAL PHARMACOLOGY: Special Populations: Geriatrics), and the greater frequency of concomitant disease or other drug therapy.

Last reviewed on RxList: 10/7/2009
This monograph has been modified to include the generic and brand name in many instances.