Lariam (Mefloquine Hydrochloride)

Lariam is an antimalarial medication used in the prevention and treatment of malaria caused by Plasmodium species.

• Malaria prophylaxis: provides preventive protection for travelers and residents in endemic areas.
• Acute uncomplicated Plasmodium falciparum malaria: clears infection and resolves symptoms.
• Chloroquine‑resistant malaria: offers an effective oral option when resistance limits other agents.

• Mefloquine interferes with the parasite’s heme detoxification pathway and disrupts membrane stability, leading to accumulation of toxic heme‑derived compounds within infected erythrocytes. By binding to parasite‑derived proteins and affecting lipid bilayers, it inhibits replication of Plasmodium species, particularly P. falciparum, thereby halting the blood‑stage lifecycle of the malaria parasite. The drug’s lipophilic nature enables it to cross the red‑cell membrane and concentrate within the parasite’s digestive vacuole, enhancing its antiplasmodial activity.

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

Common Side Effects

• Nausea
• Headache
• Dizziness

Serious or Rare Side Effects

• Neuropsychiatric reactions (e.g., anxiety, depression, psychosis)
• Seizures
• Severe allergic reactions (e.g., anaphylaxis, Stevens‑Johnson syndrome)

Before prescribing Lariam, healthcare professionals should consider several precautionary measures to minimise risk.

• Assess medical history: screen for psychiatric disorders and previous neuropsychiatric events.
• Review cardiac status: evaluate for QT‑interval prolongation or arrhythmia risk.
• Avoid in known hypersensitivity: discontinue if allergic reaction occurs.
• Caution with concomitant CNS‑active drugs: monitor for additive seizure risk.
• Store at ambient temperature: keep in the original pack, protect from moisture.

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

Major Interactions (Avoid)

• Co‑administration with other antimalarials that share metabolic pathways (e.g., quinine) may increase toxicity.
• Use with drugs that lower seizure threshold (e.g., bupropion) can precipitate seizures.
• Combination with QT‑prolonging agents (e.g., macrolide antibiotics) raises risk of cardiac arrhythmia.

Moderate Interactions (Monitor Closely)

• CYP3A4 inhibitors (e.g., erythromycin) may raise plasma levels of mefloquine.
• CYP3A4 inducers (e.g., rifampicin) can reduce therapeutic concentrations.
• Warfarin therapy may experience altered INR; monitor coagulation parameters.