Artemether - Dosing Reference

1. Artemether-Lumefantrine (AL) - Oral - Uncomplicated Malaria

• Take with food or whole milk (fat increases bioavailability)
• If the patient vomits within 30 minutes, repeat the dose
• Not recommended for weight <5 kg or in first-trimester pregnancy (use with caution in 2nd/3rd trimester if no alternative)

2. Artemether IM Injection - Severe Malaria (when IV artesunate is unavailable)

• Loading dose: 3.2 mg/kg IM on Day 1
• Maintenance: 1.6 mg/kg IM once daily for up to 5 days (until patient can take oral therapy)
• WHO 2025 guidance confirms artemether is the preferred alternative to quinine when parenteral artesunate is unavailable for both adults and children with severe malaria
• A lower-strength 20 mg/mL formulation is preferred for pediatric dosing to allow accurate small-volume administration

3. Key Notes

• Indication: AL is for uncomplicated P. falciparum malaria in chloroquine-resistant or unknown-resistance areas; also effective for P. vivax in certain regions (Indonesia, Papua New Guinea)
• Not for severe/complicated malaria - IV artesunate is first-line for severe malaria; IM artemether is the fallback
• QT prolongation risk - avoid co-administration with other QT-prolonging drugs (e.g., lumefantrine component has this risk)
• Drug interactions - use caution with antiretrovirals (may reduce artemether/DHA concentrations, reducing efficacy, or increase lumefantrine causing QT prolongation)
• G6PD: Artemether itself is safe in G6PD deficiency (unlike primaquine)

Falcigo (Artesunate Injection) - Dosing

Dose

Schedule

• Minimum parenteral course: 3 doses (0, 12, 24 h)
• Switch to a complete oral ACT course (e.g., artemether-lumefantrine) once the patient is stable and tolerating oral drugs
• If parenteral therapy must continue beyond 24 h, give once daily until oral therapy is feasible (up to 7 days total if needed)

Preparation (Falcigo vials)

1. Dissolve powder in 1 mL of 5% sodium bicarbonate (supplied) - shake for 2 minutes
2. Further dilute in 5 mL normal saline or 5% dextrose
3. Administer IV slowly over 1-2 minutes (IV bolus), or IM into the anterior thigh

• <25 kg: 1 vial (60 mg)
• 26-50 kg: 2 vials
• 51-75 kg: 3 vials
• 76-100 kg: 4 vials

Key Points

• First-line for severe malaria (WHO & CDC); preferred over quinine and artemether IM
• Follow up parenteral artesunate with a full 3-day oral ACT course to clear residual parasites
• Post-artesunate delayed haemolysis can occur 2-3 weeks after treatment - monitor Hb in high parasite burden cases
• Safe in pregnancy when benefit outweighs risk (severe malaria is life-threatening)
• Not for uncomplicated malaria - use oral AL (Coartem/Falcigo oral combinations) for those cases

Scorpion Sting in Pregnancy

Why It Is High Risk

• Maternal: autonomic storm with catecholamine surge, tachycardia, hypertension, pulmonary edema, cardiogenic shock, respiratory compromise
• Fetal: uteroplacental vasoconstriction from catecholamine excess, fetal tachycardia, hypoxia, preterm labor, miscarriage, or stillbirth (especially if treatment is delayed)

Fetal/Obstetric Risks by Literature

Management

1. Immediate Stabilization

• Admit to hospital - all pregnant women with scorpion sting require monitoring regardless of initial symptom severity
• Continuous cardiotocography (CTG) - fetal tachycardia is an early sign of systemic envenomation
• IV access, oxygen, monitor BP, SpO2, ECG
• Left lateral decubitus position to relieve aortocaval compression

2. Antivenom (most important intervention)

• Administer as early as possible for any systemic features - do not wait for symptom progression in pregnancy
• Species-specific antivenom preferred (equine Fab'2 preparations - e.g., Anascorp for Centruroides, polyvalent antivenom for other species)
• Evidence supports antivenom as safe and effective in all trimesters, including the third trimester
• Dose: 3 vials IV over 10 minutes (Centruroides/Anascorp); additional 1-vial doses every 30-60 minutes as needed
• Antivenom is indicated for Grade 3-4 envenomation (cranial nerve dysfunction, neuromuscular dysfunction, cardiovascular instability)

3. Symptom-Directed Treatment

4. Obstetric Monitoring

• Continuous fetal monitoring throughout acute phase
• Obstetric review for signs of preterm labor, placental abruption, or fetal distress
• If fetal compromise does not resolve with maternal stabilization, delivery may be needed (especially in viable 3rd trimester)
• Bring the scorpion if captured - species identification enables targeted antivenom selection and is a major outcome differentiator

Species-Specific Notes

• Centruroides (North America): primarily neuromuscular toxicity
• Mesobuthus tamulus / Indian red scorpion (India, Nepal, Pakistan): predominantly cardiovascular - prazosin is especially effective
• Androctonus / Buthus / Parabuthus (Africa, Middle East): cardiovascular + neuromuscular mixed toxicity
• Tityus (South America): cholinergic features (atropine indicated)

Bottom Line

Prazosin in Pregnancy

Drug Class & Mechanism

FDA Pregnancy Category: C

• Animal studies have shown adverse fetal effects
• No adequate, well-controlled human studies exist
• Potential benefits may warrant use despite potential risks

Safety Profile in Pregnancy

When Is It Used in Pregnancy?

Preferred Agents Over Prazosin (First-Line in Pregnancy)

Bottom Line