Lariam / Mefloquine (Mefloquine Hydrochloride)

Mefloquine is an antimalarial drug that acts on Plasmodium parasites to prevent infection and treat disease.

• Malaria prophylaxis: prevents malaria in travelers and residents of endemic regions when taken before, during, and after exposure.
• Acute uncomplicated malaria: treats infections caused by susceptible Plasmodium species, helping to clear parasites and resolve symptoms.
• Travel to endemic areas: provides chemoprophylaxis for individuals visiting regions with high malaria transmission risk.

• Mefloquine interferes with the parasite’s ability to detoxify heme released during hemoglobin digestion. By blocking heme polymerization, toxic free heme accumulates within the Plasmodium cell, leading to oxidative damage and parasite death. This action occurs primarily in the erythrocytic stage of the malaria lifecycle.

Mefloquine may cause a range of adverse reactions, from mild to severe. Patients should be aware of both common and serious possibilities.

Common Side Effects

• Nausea: mild to moderate stomach upset.
• Dizziness: sensation of light‑headedness or vertigo.
• Headache: persistent or intermittent pain.
• Insomnia: difficulty falling or staying asleep.
• Visual disturbances: blurred vision or changes in visual acuity.
• Gastrointestinal upset: abdominal cramps or diarrhea.

Serious or Rare Side Effects

• Neuropsychiatric events: anxiety, depression, or psychosis.
• Seizures: rare occurrence of convulsive episodes.
• Cardiac arrhythmias: abnormal heart rhythms.
• Severe allergic reactions: rash, swelling, or anaphylaxis.
• Hepatotoxicity: elevated liver enzymes or liver injury.
• Hemolytic anemia: destruction of red blood cells.

Before using mefloquine, certain precautions should be observed to minimize risks.

• Pregnancy: Category C – discuss potential benefits and risks with a healthcare provider.
• Breastfeeding: weigh infant exposure against maternal benefit; consult a clinician.
• Pre‑existing psychiatric conditions: avoid if history of severe depression or psychosis.
• Cardiac disease: caution in patients with known arrhythmias or conduction disorders.
• Liver impairment: monitor hepatic function and adjust use as advised.
• Store at ambient temperature: keep below 25 °C, in the original packaging, protected from moisture and direct sunlight.

Mefloquine can interact with other medicines, altering its effectiveness or safety profile.

Major Interactions (Avoid)

• Anticonvulsants (e.g., carbamazepine, phenytoin): may reduce mefloquine levels.
• QT‑prolonging agents (e.g., quinidine, haloperidol): increase risk of cardiac arrhythmias.

Moderate Interactions (Monitor Closely)

• CYP3A4 inhibitors (e.g., ketoconazole, erythromycin): may raise mefloquine concentrations.
• CYP3A4 inducers (e.g., rifampicin, St. John’s wort): may lower drug exposure.
• Other antimalarials (e.g., artesunate): assess combined toxicity risk.