ARCO TABLETS

Indications

• Malaria caused by Plasmodium falciparum
• Multidrug-resistant malaria
• Severe malaria

Dosage

Children: Refer to the BNF for Children for specific dosing guidelines in paediatric patients. Dosage is typically weight-based and may differ depending on the formulation used and the severity of the disease.

Adults: Refer to the BNF for specific dosing guidance. Generally, artemisinin is given as part of combination therapy, and the dosage may vary based on the specific formulation and clinical guidelines.

Mechanism of action

Artemisinin decreases lipid accumulation in hepatocytes by inhibiting CD36 expression and reducing TAG content. This mechanism is associated with its ability to disrupt the metabolism of malaria parasites and increase reactive oxygen species production, ultimately leading to parasite death.

Pharmacodynamics

The pharmacodynamics of artemisinin involves its rapid action against the malaria parasite. The drug is known to have a quick onset of action and effectively reduces parasitemia. Its efficacy is attributed to the production of free radicals that damage the parasite's membranes and essential cellular components, leading to cell lysis and death.

Pharmacokinetics

Artemisinin is well absorbed when administered orally, with peak plasma concentrations typically reached within 1 to 2 hours. It is extensively metabolized in the liver, primarily by cytochrome P450 enzymes, and has a half-life of about 1 to 3 hours, necessitating multiple doses for sustained antimalarial activity. The drug is excreted mainly in the urine, and its pharmacokinetics can be affected by factors such as food intake and the presence of other medications.

Pregnancy

Artemisinin use during pregnancy should be avoided, particularly in the first trimester, due to potential risks to the fetus. Alternative treatments for malaria should be considered.

Breast-feeding

Limited data are available on the excretion of artemisinin in human milk. Caution is advised when administering artemisinin to breastfeeding mothers.

Storage

Store at room temperature, away from moisture and heat. Keep out of reach of children.

Indications

• Malaria caused by Plasmodium vivax
• Malaria caused by Plasmodium ovale

Dosage

Children: Refer to the BNF for Children for pediatric dosing recommendations.

Adults: Refer to the BNF for specific adult dosing guidelines.

Mechanism of action

Naphthoquine acts by inhibiting the mitochondrial respiration of the malaria parasite. It is believed to interfere with the electron transport chain, leading to a decrease in ATP production, which is essential for the parasite's survival. The drug targets the cytochrome bc1 complex, resulting in oxidative stress and ultimately the death of the parasite.

Pharmacodynamics

The pharmacodynamic profile of naphthoquine indicates its effectiveness in killing both the asexual and hypnozoite stages of Plasmodium vivax and Plasmodium ovale. The drug's action leads to a reduction in parasitemia and alleviation of malaria symptoms. Additionally, its activity against hypnozoites is significant for the prevention of relapse, making it a valuable option in malaria treatment regimens.

Pharmacokinetics

Naphthoquine is absorbed following oral administration, with peak plasma concentrations typically occurring within a few hours. It is extensively metabolized in the liver, primarily through cytochrome P450 enzymes. The elimination half-life is variable, and the drug is excreted mainly in the urine as metabolites. Due to its lipophilic nature, naphthoquine has a significant volume of distribution, allowing it to penetrate tissues effectively.

Pregnancy

The safety of naphthoquine in pregnancy has not been established. Caution is advised.

Breast-feeding

It is not known whether naphthoquine is excreted in human milk. Caution is advised when administering to breastfeeding women.

Storage

Store in a cool, dry place, protected from light.

Formulations

• {'formulation': 'Tablet', 'strength': '100 mg'}
• {'formulation': 'Injection', 'strength': '10 mg/mL'}

Mechanism of action

A 2025 systematic review notes that Artemisinin decreases lipid accumulation in hepatocytes by inhibiting CD36 expression and reducing TAG content.