1. Clinical Overview
Artesunate is a potent, water-soluble, semi-synthetic derivative of artemisinin, a sesquiterpene lactone endoperoxide isolated from the plant Artemisia annua. It is the first-line treatment for severe and complicated Plasmodium falciparum malaria in India and globally, as per WHO and National Center for Vector Borne Diseases Control (NCVBDC) guidelines. It acts rapidly to reduce parasite biomass, providing a critical survival advantage. In India, it is a Schedule H1 drug, requiring strict prescription control.
| Onset | Duration | Bioavailability |
|---|---|---|
| Parasite clearance time: 24-48 hours. Clinical improvement (fever reduction) often within 12-24 hours. | Short; terminal elimination half-life is approximately 45 minutes (for artesunate). However, its active metabolite, dihydroartemisinin (DHA), has a half-life of 1-2 hours. The therapeutic effect is sustained through a 3-day course. | Approximately 60-70% after intramuscular injection. Oral bioavailability is variable but lower; it is rapidly hydrolyzed to DHA in the gut and liver. |
2. Mechanism of Action
The antimalarial action is mediated by the endoperoxide bridge. Inside the infected erythrocyte, the iron(II)-heme (ferrous protoporphyrin IX) generated from hemoglobin digestion by the parasite cleaves this endoperoxide bridge. This cleavage generates highly reactive carbon-centered free radicals and reactive oxygen species (ROS). These reactive intermediates alkylate and damage specific parasite proteins (including PfATP6, a SERCA-type calcium ATPase), cause oxidative stress, and inhibit nucleic acid and protein synthesis, leading to rapid parasite death.
3. Indications & Uses
- Treatment of uncomplicated Plasmodium falciparum malaria (as part of an Artemisinin-based Combination Therapy - ACT)
- First-line treatment of severe and complicated malaria (via intravenous/intramuscular injection)
4. Dosage & Administration
Adult Dosage: For uncomplicated malaria (as ACT): Typically, Artesunate 100mg twice on day 1, then once daily for next 2 days (total 4mg/kg over 3 days) combined with a partner drug. A 50mg tablet is part of this regimen. For severe malaria (IV/IM): 2.4 mg/kg at 0, 12, and 24 hours, then once daily until oral therapy can be started.
Administration: Oral: Take with food to enhance absorption and reduce GI upset. Complete the full 3-day course even if symptoms improve. Do not crush or chew dispersible tablets; disperse in a small amount of water. Parenteral: Administered by healthcare professionals only, via slow IV injection or deep IM injection.
5. Side Effects
Common side effects may include:
- Headache
- Dizziness
- Nausea
- Abdominal pain
- Anorexia
- Cough (in children)
- Transient reticulocytopenia (dose-dependent)
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Strong CYP2A6 Inducers (e.g., Rifampicin, Phenobarbital) | May increase metabolism of DHA, potentially reducing artesunate efficacy. | Moderate |
| Antiepileptics (e.g., Carbamazepine, Phenytoin) | Potential induction of metabolism, reducing efficacy. | Moderate |
| Mefloquine | Increased risk of QT prolongation and neuropsychiatric effects. Administer sequentially in ACT; artesunate first. | Moderate |
| Other Antimalarials (e.g., Chloroquine, Quinine) | Additive therapeutic effect, but specific combinations are not standard ACT. Do not use monotherapy. | Low |
7. Patient Counselling
- DO complete the full 3-day course of combination therapy, even if you feel better.
- DO take the tablets with food or milk.
- DO inform your doctor if you are pregnant, planning pregnancy, or breastfeeding.
- DONT take artesunate as a monotherapy (single drug).
- DONT skip doses.
- DONT use it for fever prevention (prophylaxis).
8. Toxicology & Storage
Overdose: Limited data. Potential symptoms may include severe dizziness, nausea, vomiting, cardiac conduction abnormalities (prolonged QT interval), and neurological toxicity (ataxia, slurred speech, nystagmus). Bone marrow suppression (reticulocytopenia, neutropenia) may occur with massive overdose.
Storage: Store below 30°C. Protect from moisture. Keep in the original blister pack until use. Do not freeze. Keep out of reach of children. For injectable forms: Store below 25°C. Reconstituted solution should be used immediately.