Mefloquine

Aka: Mefloquine, Lariam, Mefloquine Toxicity

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II. Indications

  1. Prophylaxis or Treatment of Malaria
    1. Preferred Malaria Prophylaxis agent in Chloroquine resistance areas (esp. longterm travel >6 months)
    2. Less commonly used for Malaria treatment

III. Contraindications

  1. Mefloquine resistant Malaria regions (some regions within southeast asia)
  2. History of Epilepsy (Seizure Disorder)
  3. History of major psychiatric disorder
  4. Cardiac conduction abnormalities (esp. QTc Prolongation)
  5. Concomitant Beta Blocker use
  6. First Trimester Pregnancy
    1. May be used in second or third trimester pregnancy
  7. Children under age 3 months

IV. Mechanism

  1. Developed in the 1970s at Walter Reed Army Institute of Research (WRAIR) as an alternative to Chloroquine
  2. Structural analog of Quinine
    1. Quinoline ring with Methanol group
  3. Mefloquine is active during the erythrocytic stage of Malaria (but not the hepatic stage)
    1. Mefloquine concentrates in erythrocytes (within parasitic vacuoles)
    2. Mefloquine inhibits heme detoxification by Parasites

V. Medications

  1. Mefloquine Tablets: 250 mg
    1. Take with food and full 8 oz glass of water
    2. Tablets may be crushed and mixed with a small amount of water, milk or other liquids

VI. Dosing: Malaria Prophylaxis

  1. Protocol
    1. Start dosing 1 week before exposure
    2. Complete dosing 4 weeks after exposure
  2. Adult
    1. Mefloquine 250 mg salt (228 mg base) orally once weekly
  3. Child
    1. Weight <9 kg
      1. Mefloquine 5 mg/kg salt (4.6 mg/kg base) orally once weekly
    2. Weight 9 to 19 kg
      1. Mefloquine 1/4 of adult tablet orally once per week
    3. Weight: 20 to 30 kg
      1. Mefloquine 1/2 of adult tablet orally once per week
    4. Weight: 31 to 45 kg
      1. Mefloquine 3/4 of adult tablet orally once per week
    5. Weight: >45 kg
      1. Mefloquine 1 adult tablet (250 mg) orally once per week

VII. Dosing: Malaria Treatment (CDC Guidelines)

  1. Adult
    1. Dose 1: Mefloquine 750 mg salt (684 mg base)
    2. Dose 2: Mefloquine 500 mg salt (456 mg base) in 8 to 12 hours after first dose
  2. Child
    1. Dose 1: Mefloquine 15 mg/kg salt (13.7 mg/kg base)
    2. Dose 2: Mefloquine 10 mg/kg salt (9.1 mg/kg base) in 8 to 12 hours after first dose

VIII. Pharmacokinetics

  1. Half-Life: 33 days
  2. Peak Effect (oral): 6-24 hours
  3. Steady state reached
    1. Weekly dose: 7 weeks
    2. Loading dose: 4 days
  4. Metabolism: CYP3A4
  5. Distribution
    1. Highly lipophilic (results in a very long half life)
    2. Highly Protein bound
    3. Large volume of distribution
    4. Easily crosses blood brain barrier with risks of neurotoxicity in Overdose

IX. Adverse Effects: Standard Dosing

  1. Vestibular toxicity
    1. Risk of longterm Vertigo and Tinnitus
  2. Arrhythmia in patients with cardiac conduction defect
    1. QT Prolongation
    2. Sinus Bradycardia
  3. Neuropsychological effects (uncommon 1:200 to 1:500, but is a FDA black box warning)
    1. Insomnia
    2. Nightmares
    3. Anxiety
    4. Irritability
    5. Drowsiness
    6. Dizziness or Vertigo
    7. Tinnitus
    8. Headache
    9. Major Depression
      1. Possible increased Suicidality
    10. Psychosis (paranoia, Hallucinations) or Seizures (rare)
      1. Prophylaxis Incidence: <1:10,000
      2. Treatment Incidence: 1:100 to 1:1500

X. Adverse Effects: Overdose/Toxicity (Ingestions >1.5 g)

  1. Gastrointestinal
    1. Nausea
    2. Vomiting
    3. Diarrhea
  2. Endocrine
    1. Hypoglycemia (high Insulin levels)
  3. Cardiovascular
    1. Bradycardia
    2. QT Prolongation
  4. Neurotoxicity
    1. See adverse effects at standard doses above
    2. Seizures
    3. Encephalopathy
    4. Hyperactive Delirium
  5. Management of Overdose
    1. See Unknown Ingestion
    2. Oral Activated Charcoal if ingestion in last 1-2 hours (airway precautions)
    3. Hypoglycemia
      1. See Hypoglycemia Management
      2. IV Dextrose
    4. Seizures
      1. See Status Epilepticus
      2. Benzodiazepines
    5. Anticholinergic Toxicity with Antimuscarinic Poisoning effects
      1. See Anticholinergic Toxicity
      2. Consider Physostigmine
    6. Disposition
      1. Admit all symptomatic Overdoses
      2. Observe asymptomatic Overdoses for neurotoxicity for 24 hours
  6. References
    1. Carroll and Yakey (2025) Crit Dec Emerg Med 39(8): 42

XI. Safety

  1. Considered safe in Lactation
    1. However, infant is not protected from Malaria by Breast Feeding (minimal medication in Breast Milk)
  2. Pregnancy Category B
    1. No significant adverse fetal affects in studies (any trimester)

XII. Drug Interactions

  1. Avoid Mefloquine for at least 12 hours after last dose of the following
    1. Quinidine
    2. Quinine
    3. Chloroquine
  2. Agents to avoid overall with Mefloquine
    1. Ziprasidone
  3. Agents that decrease Mefloquine levels
    1. Rifampin
  4. Agents that are decreased by Mefloquine
    1. Valproate

XIII. Resources

  1. Mefloquine (DailyMed)
    1. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=09716a24-d7da-42b2-af29-c03a1b6670bd

XIV. References

  1. (2013) Presc Lett 20(9)
  2. (2019) Drugs for Malaria Prophylaxis, Med Lett Drugs Ther, p. e104-5
  3. (2023) Presc Lett, Malaria Prophylaxis, Resource #350806
  4. Boudreau (1993) Trop Med Parasitol 44(3):257-65 [PubMed]
  5. Vanhauwere (1998) Am J Trop Med Hyg 58:17-21 [PubMed]
  6. Weimeke (1991) Am J Trop Med Hyg 45:86-9 [PubMed]
  7. Shahbodaghi (2022) Am Fam Physician 106(3): 270-8 [PubMed]

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Cost: Medications

mefloquine (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
MEFLOQUINE HCL 250 MG TABLET Generic $3.99 each
FPNotebook does not benefit financially from showing this medication data or their pharmacy links. This information is provided only to help medical providers and their patients see relative costs. Insurance plans negotiate lower medication prices with suppliers. Prices shown here are out of pocket, non-negotiated rates. See Needy Meds for financial assistance information. GoodRx is another tool for finding lower drug prices.

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