Lariam (mefloquine hydrochloride) is a prescription antimalarial medication indicated for the prophylaxis of Plasmodium falciparum and Plasmodium vivax malaria in travelers. As a long-acting chemoprophylactic agent, it offers robust protection in regions with chloroquine-resistant malaria strains. Its weekly dosing regimen provides significant convenience for extended travel, though it requires careful patient screening and adherence to prescribing guidelines due to its potential for neuropsychiatric adverse effects. Medical supervision is essential to ensure appropriate patient selection and risk mitigation.

Features

• Active ingredient: Mefloquine hydrochloride (250 mg per tablet)
• Formulation: Film-coated tablet for oral administration
• Dosing schedule: Weekly prophylaxis regimen
• Spectrum: Effective against chloroquine-resistant P. falciparum and P. vivax
• Half-life: Approximately 2-4 weeks, allowing sustained protection
• Manufacturer: Originally developed by Hoffmann-La Roche; available as generic mefloquine
• Regulatory status: FDA-approved prescription medication

Benefits

• Provides reliable weekly dosing convenience for long-term travelers and expatriates
• Offers protection in multidrug-resistant malaria regions where other prophylactics fail
• Maintains therapeutic blood concentrations for weeks after discontinuation
• Reduces malaria infection risk by approximately 90% when taken correctly
• Eliminates need for daily medication adherence during travel
• Coverage extends to both hepatic and erythrocytic stages of malaria parasites

Common use

Lariam is primarily prescribed for malaria prophylaxis in non-immune travelers aged ≥18 years visiting endemic areas with chloroquine-resistant malaria. It is particularly valuable for military personnel, aid workers, and long-term travelers to sub-Saharan Africa, Southeast Asia, and South America. The medication is also used off-label for treatment of acute malaria infections in specific clinical scenarios, though this requires different dosing protocols and close medical supervision.

Dosage and direction

Prophylaxis in adults: 250 mg (one tablet) orally once weekly. Begin administration 2-3 weeks before travel to assess tolerance, continue weekly during exposure, and maintain for 4 weeks after leaving endemic area. Take with at least 8 oz of water, preferably after the evening meal to minimize gastrointestinal discomfort.

Pediatric dosing: Not recommended for children under 5 kg or 3 months of age. For children >45 kg: adult dose; 31-45 kg: ¾ tablet; 21-30 kg: ½ tablet; 11-20 kg: ¼ tablet; 5-10 kg: ⅛ tablet. Always consult pediatric infectious disease specialist for children.

Treatment dosing: 1250 mg (5 tablets) as single dose under direct medical supervision only. Not recommended as first-line treatment due to side effect profile.

Precautions

• Conduct thorough medical and psychiatric history assessment before prescribing
• Monitor for early signs of neuropsychiatric reactions (dizziness, confusion, anxiety)
• Avoid in patients with history of depression, anxiety disorders, or psychosis
• Use caution in patients with cardiac conduction abnormalities or seizure disorders
• Regular liver function tests recommended during prolonged use
• Not recommended for persons with occupational requirements for fine motor coordination
• Pregnancy Category C: Use only if potential benefit justifies potential fetal risk
• Breastfeeding: Mefloquine excreted in milk; weigh risks versus benefits

Contraindications

• Known hypersensitivity to mefloquine or related compounds
• History of or active depression, generalized anxiety disorder, psychosis, or other major psychiatric disorders
• History of convulsions or epilepsy
• Cardiac conduction abnormalities (prolonged QT interval, arrhythmias)
• Severe hepatic impairment
• Concurrent administration with halofantrine or ketoconazole
• Previous mefloquine prophylaxis with associated neuropsychiatric reactions

Possible side effects

Common (≥1%): Dizziness, headache, sleep disorders (insomnia, vivid dreams), gastrointestinal disturbances (nausea, diarrhea, abdominal pain), visual disturbances, loss of balance

Less common (0.1-1%): Tinnitus, hair loss, skin rash, pruritus, fatigue, tachycardia

Serious (<0.1%): Neuropsychiatric reactions (severe depression, anxiety, paranoia, hallucinations, suicidal ideation), convulsions, encephalopathy, polyneuropathy, hemolytic anemia, pneumonitis

Post-marketing reports: Stevens-Johnson syndrome, toxic epidermal necrolysis, blood dyscrasias, oculogyric crises

Drug interaction

• Contraindicated combinations: Halofantrine (increased risk of QT prolongation), ketoconazole (increased mefloquine concentrations)
• Significant interactions: Anticonvulsants (reduced seizure threshold), beta-blockers (potential bradycardia), chloroquine (increased seizure risk), live vaccines (theoretical reduced efficacy)
• Moderate interactions: Anticoagulants (monitor INR), cyclosporine (reduced levels), antidiabetic agents (monitor glucose)
• QT-prolonging agents: Use with caution with antiarrhythmics, antipsychotics, antidepressants
• Alcohol: May enhance neurological side effects

Missed dose

If a weekly dose is missed, take it as soon as possible. If within 2 days of next scheduled dose, skip missed dose and resume regular schedule. Never double dose. If vomiting occurs within 30 minutes of ingestion, repeat full dose. If vomiting occurs 30-60 minutes after ingestion, repeat half dose. Maintain weekly schedule thereafter. Extended missed doses may require restarting prophylaxis protocol.

Overdose

Symptoms may include exaggerated side effects: severe nausea/vomiting, dizziness, syncope, convulsions, cardiac arrhythmias. Management involves gastric lavage if presented early, activated charcoal, and symptomatic treatment. Cardiac monitoring essential for 24 hours due to QT prolongation risk. No specific antidote exists. Supportive care includes electrolyte management and antiemetics. Dialysis not effective due to high protein binding.

Storage

Store at controlled room temperature (15-30°C/59-86°F) in original container. Protect from light and moisture. Keep tightly closed. Do not store in bathroom or damp areas. Keep out of reach of children and pets. Do not use after expiration date. Properly dispose of unused medication through take-back programs.

Disclaimer

This information is for educational purposes only and does not constitute medical advice. Prescription and use of Lariam requires consultation with a healthcare professional familiar with travel medicine. Individual risk assessment is mandatory. The prescriber must evaluate destination-specific malaria risk, patient medical history, and alternative options. Medication decisions should balance efficacy against potential adverse effects. Always follow national and international malaria prophylaxis guidelines.

Reviews

Clinical evidence supports Lariam’s efficacy in malaria prevention, though careful patient selection is crucial. Systematic reviews demonstrate 85-95% protective efficacy against P. falciparum when adherence is maintained. The WHO includes mefloquine in its essential medicines list for malaria prophylaxis. However, post-marketing surveillance indicates significant neuropsychiatric adverse effects in susceptible individuals. Current guidelines recommend reserving Lariam for specific scenarios where benefits outweigh risks and alternatives are unsuitable. Patient education about potential side effects and early warning signs is essential for safe use.