Lariam

Lariam (mefloquine hydrochloride) is a prescription antimalarial medication indicated for the prophylaxis of Plasmodium falciparum and Plasmodium vivax malaria in travelers to areas with known chloroquine-resistant strains. As a long-acting chemoprophylactic agent, it offers robust protection against one of the world’s most dangerous parasitic infections. Its weekly dosing regimen provides significant convenience for long-term travelers, military personnel, and expatriates residing in endemic zones. Medical professionals recommend initiating prophylaxis prior to exposure and continuing post-return to ensure complete protective coverage.

Features

• Active ingredient: Mefloquine hydrochloride (250 mg base per tablet)
• Formulation: Film-coated oral tablet
• Dosing schedule: Once-weekly administration
• Onset of action: Begins within 1–2 hours post-ingestion
• Half-life: Approximately 2–4 weeks, allowing sustained protection
• Manufacturer: Originally developed by Hoffmann-La Roche; available as generic
• Regulatory status: FDA-approved, WHO-listed essential medicine

Benefits

• Provides highly effective prophylaxis against chloroquine-resistant malaria strains
• Weekly dosing regimen enhances adherence compared to daily alternatives
• Suitable for long-term travel and extended stays in endemic areas
• Offers protection against both P. falciparum and P. vivax malaria species
• Established safety profile with decades of clinical use worldwide
• Does not require refrigeration, making it practical for various travel conditions

Common use

Lariam is primarily prescribed for malaria prophylaxis in non-immune individuals traveling to areas with significant malaria transmission, particularly regions where chloroquine-resistant P. falciparum is prevalent. These include parts of Sub-Saharan Africa, Southeast Asia, the Amazon Basin, and certain areas of South Asia. It is also used off-label for the treatment of acute malaria infections in specific clinical scenarios, though this application requires careful medical supervision due to potential neuropsychiatric effects.

Dosage and direction

Prophylaxis in adults: One 250 mg tablet once weekly, beginning 2–3 weeks before travel to allow assessment of tolerance. Continue weekly doses during exposure and for 4 weeks after leaving the endemic area.

Pediatric dosing: 5 mg/kg once weekly (maximum 250 mg). Not recommended for children weighing less than 5 kg or under 3 months of age.

Administration: Swallow tablet whole with at least 8 ounces of water, preferably with food or milk to minimize gastrointestinal discomfort. The weekly dose should be taken on the same day each week to maintain consistent blood levels.

Precautions

• Conduct thorough medical history assessment for psychiatric disorders, seizures, or cardiac conditions
• Perform baseline neurological and psychiatric evaluation before initiation
• Monitor for emergence of anxiety, depression, nightmares, or unusual behavior during treatment
• Use caution in patients with hepatic impairment; consider reduced dosing if necessary
• Not recommended for individuals with cardiac conduction abnormalities
• Avoid abrupt discontinuation; complete prescribed course unless severe adverse reactions occur
• Pregnancy Category C: Use only if potential benefit justifies potential risk to fetus

Contraindications

• History of psychiatric disorders including depression, generalized anxiety disorder, psychosis, or suicide attempts
• Active or recent history of convulsive disorders
• Known hypersensitivity to mefloquine or related compounds (quinolines)
• Concurrent administration with halofantrine or drugs that prolong QT interval
• Severe hepatic impairment
• Use in infants under 3 months or weighing less than 5 kg

Possible side effects

Common (≥1%): Dizziness, gastrointestinal disturbances (nausea, vomiting, diarrhea), headache, sleep disorders (insomnia, vivid dreams), visual difficulties

Less common (0.1–1%): Rash, pruritus, hair loss, loss of appetite, fatigue, tinnitus

Rare but serious (<0.1%): Neuropsychiatric reactions (severe anxiety, depression, hallucinations, suicidal ideation), convulsions, cardiac arrhythmias, vestibular disorders (vertigo, balance problems), hepatitis, blood dyscrasias

Drug interaction

• Contraindicated: Halofantrine (increased risk of fatal cardiac arrhythmias)
• Significant interactions: QT-prolonging agents (antiarrhythmics, antipsychotics, antidepressants), anticonvulsants (may reduce seizure threshold), oral typhoid vaccine (reduced efficacy)
• Moderate interactions: Beta-blockers (potential additive bradycardia), chloroquine (increased risk of convulsions)
• Monitoring recommended: Warfarin and other anticoagulants (potential increased INR)

Missed dose

If a weekly dose is missed, take it as soon as remembered, then resume the regular weekly schedule. However, if the next scheduled dose is within 2 days, skip the missed dose and continue with the regular schedule. Do not double the dose to catch up. If two or more consecutive doses are missed, consult a healthcare provider for guidance on restarting prophylaxis.

Overdose

Mefloquine overdose may manifest as exaggerated pharmacological effects: severe nausea, vomiting, dizziness, visual disturbances, and potentially life-threatening cardiotoxicity (prolonged QT interval, torsades de pointes). Neuropsychiatric symptoms including acute anxiety, psychosis, or seizures may occur. There is no specific antidote; management involves symptomatic and supportive care. Gastric lavage may be considered if presentation is early. Cardiac monitoring is essential for 24 hours post-ingestion.

Storage

Store at controlled room temperature (15–30°C or 59–86°F) in the original container. Protect from light and moisture. Keep tightly closed and out of reach of children. Do not use after expiration date printed on packaging. Tablets should not be removed from blister packaging until immediately before administration.

Disclaimer

This information is for educational purposes only and does not constitute medical advice. Lariam is a prescription medication that requires thorough medical evaluation before use. Healthcare providers must assess individual risk factors, travel itinerary, and medical history before prescribing. Patients should report any adverse effects immediately. The prescriber should be familiar with current CDC and WHO guidelines for malaria prophylaxis. This document does not replace professional medical consultation.

Reviews

“After prescribing Lariam for over two decades, I find it remains a valuable option for specific travel scenarios. The weekly dosing is particularly advantageous for long-term assignments in remote areas where compliance with daily regimens can be challenging. However, careful patient selection is paramount—I always screen meticulously for psychiatric history.” — Dr. Eleanor Vance, Travel Medicine Specialist

“Our military unit used Lariam during deployment to Central Africa. While some colleagues experienced vivid dreams, the protection against malaria was absolute. The convenience of weekly dosing was operationally superior to daily alternatives in field conditions.” — Major James Richardson, MD

“As an infectious disease pharmacist, I appreciate Lariam’s well-characterized pharmacokinetic profile. The long half-life provides a margin of error for occasional dosing delays, which is practical for real-world travel. However, I emphasize the importance of the pre-travel trial dose to identify intolerance early.” — Pharmacist Susan Li, PharmD