Atovaquone/proguanil, sold under the brand name Malarone among others, is a

fixed-dose combination A combination drug is a combination of two or more pharmaceutical drugs as active ingredients combined into a single dosage form, typically as a ''fixed-dose combination'', with each constituent standardized to specifications of a fixed dose. Fix ...

medication used to treat and prevent

malaria Malaria is a Mosquito-borne disease, mosquito-borne infectious disease that affects vertebrates and ''Anopheles'' mosquitoes. Human malaria causes Signs and symptoms, symptoms that typically include fever, Fatigue (medical), fatigue, vomitin ...

, including

chloroquine Chloroquine is an antiparasitic medication that treats malaria. It works by increasing the levels of heme in the blood, a substance toxic to the malarial parasite. This kills the parasite and stops the infection from spreading. Certain types ...

-resistant malaria. It contains

atovaquone Atovaquone, sold under the brand name Mepron, is an antimicrobial medication for the prevention and treatment of ''Pneumocystis jirovecii'' pneumonia (PCP). Atovaquone is a chemical compound that belongs to the class of naphthoquinones. Atova ...

and

proguanil Proguanil, also known as chlorguanide and chloroguanide, is a medication used to treat and prevent malaria. It is often used together with chloroquine or atovaquone. When used with chloroquine the combination will treat mild chloroquine resist ...

. It is not recommended for severe or complicated malaria. It is taken by mouth. Common side effects include abdominal pain, vomiting, diarrhea, cough, and itchiness. Serious side effects may include

anaphylaxis Anaphylaxis (Greek: 'up' + 'guarding') is a serious, potentially fatal allergic reaction and medical emergency that is rapid in onset and requires immediate medical attention regardless of the use of emergency medication on site. It typicall ...

Stevens–Johnson syndrome Stevens–Johnson syndrome (SJS) is a type of severe skin reaction. Together with toxic epidermal necrolysis (TEN) and #Classification, Stevens–Johnson/toxic epidermal necrolysis (SJS/TEN) overlap, they are considered febrile mucocutaneous d ...

hallucinations A hallucination is a perception in the absence of an external stimulus that has the compelling sense of reality. They are distinguishable from several related phenomena, such as dreaming ( REM sleep), which does not involve wakefulness; pse ...

, and liver problems. Side effects are generally mild. It is unclear if use during pregnancy or breastfeeding is safe for the baby. It is not recommended to prevent malaria in those with poor kidney function. Atovaquone works by interfering with the function of

mitochondria A mitochondrion () is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is us ...

in malaria while proguanil blocks

dihydrofolate reductase Dihydrofolate reductase, or DHFR, is an enzyme that reduces dihydrofolic acid to tetrahydrofolic acid, using NADPH as an electron donor, which can be converted to the kinds of tetrahydrofolate cofactors used in one-carbon transfer chemistry. ...

. Atovaquone/proguanil was approved for medical use in the United States in 2000. It has been available as a

generic medication A generic drug is a pharmaceutical drug that contains the same chemical substance as a drug that was originally protected by chemical patents. Generic drugs are allowed for sale after the patents on the original drugs expire. Because the active ch ...

since 2011.

Medical uses

Malaria treatment

Atovaquone/proguanil is not normally used to treat severe malaria, when an injectable drug such as

quinine Quinine is a medication used to treat malaria and babesiosis. This includes the treatment of malaria due to ''Plasmodium falciparum'' that is resistant to chloroquine when artesunate is not available. While sometimes used for nocturnal leg ...

is used instead.

Malaria prevention

Since some malaria strains are resistant to atovaquone/proguanil, it is not effective in all parts of the world. It must be taken with a fatty meal, or at least some milk, for the body to absorb it adequately—and to avoid painful stomach irritation, which proguanil frequently causes if taken without food.

Resistance

Proguanil acts as a

mitochondrial A mitochondrion () is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is used ...

sensitiser and synergizes with atovaquone. When atovaquone is used as a sole agent, a high natural frequency of

cytochrome b Cytochrome b is a protein found in the membranes of aerobic cells. In eukaryotic mitochondria (inner membrane) and in aerobic prokaryotes, cytochrome b is a component of respiratory chain complex III () — also known as the bc1 complex or ubiq ...

mutants leads to a high failure rate. This is potentially due to the high lipophilicity and slow uptake of atovaquone, which results in a relatively prolonged period of parasite exposure at ineffective concentrations. Specific mutations (''Y268S'', ''Y268C'') have been shown to confer resistance ''in vivo'', but the other mechanisms of resistance remain unknown.

Adverse effects

Side effects are generally mild. While some people experience side effects, such as coughing, diarrhea, dizziness, headache, loss of appetite, mouth sores, nausea, stomach pain, vomiting, or weakness, the majority have none or few of these.

Mechanism of action

Atovaquone selectively inhibits the malarial cytochrome ''bc''₁ complex in the parasitic

electron transport chain An electron transport chain (ETC) is a series of protein complexes and other molecules which transfer electrons from electron donors to electron acceptors via redox reactions (both reduction and oxidation occurring simultaneously) and couples th ...

, collapsing the mitochondrial membrane potential. The malarial electron transport chain does not contribute significantly to ATP synthesis; thus, it is believed that parasite death is due to the indirect inhibition of dihydroorotate dehydrogenase, which requires transport chain function and is essential to pyrimidine biosynthesis. Proguanil, via its metabolite

cycloguanil Cycloguanil is a dihydrofolate reductase inhibitor, and is a metabolite of the antimalarial drug proguanil; its formation in vivo has been thought to be primarily responsible for the antimalarial activity of proguanil. However, more recent work ...

, functions as a

dihydrofolate reductase inhibitor A dihydrofolate reductase inhibitor (DHFR inhibitor) is a molecule that inhibits the function of dihydrofolate reductase, and is a type of antifolate. Since folate is needed by rapidly dividing cells to make thymine, this effect may be used to th ...

, halting parasitic deoxythymidylate synthesis.

Chemistry

A standard tablet of Malarone contains 100 mg of proguanil hydrochloride and 250 mg of atovaquone. A pediatric tablet contains 25 mg of proguanil hydrochloride and 62.5 mg of atovaquone.

History

Glaxo Wellcome GSK plc (an acronym from its former name GlaxoSmithKline plc) is a British Multinational corporation, multinational Pharmaceutics, pharmaceutical and biotechnology company with headquarters in London. It was established in 2000 by a Mergers an ...

patented the combination of atovaquone and proguanil to treat malaria in 1999. Patent protection expired in 2013. The U.S.

Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respo ...

(FDA) approved a generic formulation from Glenmark Generics in 2011. In February 2013, the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...

High Court revoked Glaxo's patent on grounds of obviousness, which clears the way for firms to sell generic versions there.

References

{{DEFAULTSORT:Atovaquone Proguanil Combination antiviral drugs Antimalarial agents Antiprotozoal agents Drugs developed by GSK plc Wikipedia medicine articles ready to translate