Lariam (Mefloquine Hydrochloride)

Lariam (mefloquine) is a quinoline antimalarial used in the prevention and treatment of malaria caused by Plasmodium species.

• Prevention of malaria infection: provides chemoprophylaxis for travelers and residents in endemic regions.
• Acute uncomplicated Plasmodium falciparum malaria: clears parasitemia and resolves clinical symptoms.
• Acute uncomplicated Plasmodium vivax malaria: eliminates blood‑stage parasites to achieve cure.

• Mefloquine interferes with the malaria parasite’s ability to detoxify haemoglobin degradation products within its food vacuole. By disrupting haem polymerisation, toxic haem accumulates, leading to oxidative stress and parasite death. The drug accumulates in the parasite’s cytoplasm, binding to membrane proteins and impairing mitochondrial function, which further contributes to its lethal effect.

Mefloquine may cause a range of adverse reactions, which are categorized by frequency and severity.

Common Side Effects

• Nausea
• Dizziness
• Headache
• Vivid dreams

Serious or Rare Side Effects

• Anxiety or depression
• Psychosis
• Seizures
• Severe allergic reactions (e.g., anaphylaxis)

Before prescribing Lariam, clinicians should evaluate patient history and follow safety measures to minimise risks.

• Assess medical history: screen for prior psychiatric disorders or severe depression.
• Review cardiac status: avoid use in patients with known arrhythmias or prolonged QT interval.
• Evaluate pregnancy status: use only if potential benefit justifies potential risk to the fetus.
• Monitor liver function: consider baseline hepatic tests in patients with liver disease.
• Store at ambient temperature: keep in the original pack, protect from moisture.

Mefloquine can interact with other medicines, altering its concentration or increasing the risk of adverse effects.

Major Interactions (Avoid)

• Quinidine: co‑administration can raise mefloquine plasma levels, increasing toxicity.
• Strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole): may elevate drug exposure.
• Anticonvulsants that lower seizure threshold: concurrent use may exacerbate neuropsychiatric effects.

Moderate Interactions (Monitor Closely)

• Rifampin: induces metabolism, potentially reducing efficacy.
• St. John’s Wort: enzyme induction may decrease mefloquine concentrations.
• Certain antidepressants (e.g., SSRIs): may increase risk of neuropsychiatric side effects.