Lariam (Mefloquine)

• Mefloquine is an antimalarial that acts on the blood stage of Plasmodium parasites.
• Prevention of malaria infection: provides prophylactic protection for travelers and residents in endemic areas when taken before, during, and after exposure.
• Acute uncomplicated Plasmodium falciparum malaria: achieves rapid parasite clearance and clinical cure in patients with susceptible infections.
• Acute uncomplicated Plasmodium vivax malaria: eliminates blood‑stage parasites to resolve symptoms and prevent disease progression.

• Mefloquine interferes with the parasite’s ability to detoxify heme released during hemoglobin digestion, leading to accumulation of toxic heme‑derived radicals. It also disrupts parasite membrane integrity and inhibits protein synthesis, causing irreversible damage to the malaria parasite’s cellular functions and resulting in parasite death. The drug accumulates within the parasite’s food vacuole, where it binds to phospholipids and interferes with calcium homeostasis, further compromising parasite viability.

Mefloquine may cause a range of adverse reactions, varying from mild to severe.

Common Side Effects

• Dizziness: sensation of light‑headedness or imbalance.
• Nausea: feeling of queasiness, sometimes with vomiting.
• Headache: mild to moderate pain in the head.
• Insomnia: difficulty falling or staying asleep.
• Vivid dreams: intense, often disturbing dream imagery.
• Abdominal pain: discomfort or cramping in the stomach area.

Serious or Rare Side Effects

• Psychiatric disturbances: anxiety, depression, or psychotic episodes.
• Seizures: convulsive episodes requiring medical attention.
• Severe allergic reactions: anaphylaxis, Stevens‑Johnson syndrome, or toxic epidermal necrolysis.
• Hepatotoxicity: elevated liver enzymes or liver injury.
• Cardiac arrhythmias: QT interval prolongation leading to irregular heartbeats.
• Visual disturbances: blurred vision, photophobia, or loss of visual acuity.

Before prescribing mefloquine, clinicians should evaluate several safety considerations.

• Assess medical history: identify prior psychiatric disorders, cardiac disease, or seizures.
• Evaluate cardiac risk: perform ECG to detect QT prolongation where indicated.
• Avoid use in pregnancy: discuss potential fetal risks and consider alternatives.
• Monitor liver function: conduct baseline and periodic liver enzyme tests.
• Counsel on adherence: emphasize completing the full course to prevent resistance.
• Store at ambient temperature: keep tablets in original packaging, protect from moisture and direct sunlight.

Mefloquine can interact with other medicines, affecting its efficacy or safety.

Major Interactions (Avoid)

• Antacids (aluminum or magnesium): reduce mefloquine absorption.
• Strong CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin): increase plasma concentrations, raising toxicity risk.
• QT‑prolonging agents (e.g., quinidine, haloperidol): additive risk of cardiac arrhythmias.

Moderate Interactions (Monitor Closely)

• Other antimalarials (e.g., atovaquone‑proguanil): may alter therapeutic effect.
• Warfarin: potential alteration of anticoagulant effect, monitor INR.
• Oral contraceptives: possible reduction in contraceptive efficacy, advise additional methods.
• Rifampicin: may decrease mefloquine levels, consider dose adjustment.