Action

Unknown. Thought to increase intravesicular pH in parasite acid vesicles and form complexes with hemin, inhibiting parasite development.

Availability

Tablets: 250 mg

Indications and dosages

➣ Acute malarial infection

Adults: 1,250 mg P.O. as a single dose

Children: 20 to 25 mg/kg P.O. in two divided doses given 6 to 8 hours apart

➣ Malaria prophylaxis

Adults and children weighing more than 45 kg (99 lb): 250 mg P.O. once weekly on same day each week, starting 1 week before entering endemic area and continuing for 4 weeks after leaving area

Children weighing 30 to 45 kg (66 to 99 lb): 187.5 mg P.O. q week

Children weighing 20 to 30 kg (44 to 66 lb): 125 mg P.O. q week

Children weighing 10 to 20 kg (22 to 44 lb): 62.5 mg P.O. q week

Children weighing 5 to 10 kg (11 to 22 lb): 31.25 mg P.O. q week

Contraindications

• Hypersensitivity to drug, related agents (quinine, quinidine), or excipients

• Prophylactic use in patients with active depression, recent history of depression, generalized anxiety disorder, psychosis, schizophrenia, other psychiatric disorders, or history of seizures

Precautions

Use cautiously in:

• cardiac disorders, seizure disorders

• pregnant or breastfeeding patients

• children.

Administration

• Don't give on empty stomach. Administer with at least 240 ml of water.

• Know that after completing mefloquine therapy for acute malarial infection, patient should receive primaquine (or other 8-aminoquinolone) to prevent relapse.

Adverse reactions

CNS: dizziness, syncope, headache, psychotic changes, depression, hallucinations, confusion, anxiety, fatigue, vertigo, seizures

EENT: blurred vision, tinnitus

GI: nausea, vomiting, diarrhea, loose stools, abdominal discomfort, anorexia

Hematologic: leukopenia, thrombocytopenia

Musculoskeletal: myalgia

Skin: rash

Other: fever, chills

Interactions

Drug-drug. Beta-adrenergic blockers, quinidine, quinine: ECG abnormalities, cardiac arrest

Chloroquine, quinine: increased risk of seizures

Valproic acid: decreased valproic acid blood level, loss of seizure control

Drug-diagnostic tests. Hematocrit, platelets, white blood cells: decreased values

Transaminases: transient increases

Patient monitoring

See Monitor patient with acute Plasmodium vivax malaria who is at high risk for relapse. Because drug doesn't eliminate exoerythrocytic (hepaticphase) parasites, patient should receive primaquine after mefloquine therapy.

See Watch for psychiatric symptoms, such as acute anxiety, depression, restlessness, or confusion. These may precede more serious psychiatric events.

• Evaluate hepatic function during prolonged prophylactic therapy.

See In patients receiving related drugs (such as quinine, quinidine, or chloroquine) concurrently, be alert for ECG abnormalities and seizures. Separate administration times by at least 12 hours.

See Closely monitor patients with serious or life-threatening Plasmodium falciparum infection. Be aware that they should receive I.V. antimalarial drugs and that mefloquine may be used to complete course of therapy.

Patient teaching

• Tell patient to take with full glass of water and not on empty stomach.

• In prophylactic use, instruct patient to take first dose 1 week before departure and to continue therapy as prescribed upon return. Tell him to take drug on same day each week.

• Advise patient to report fever after returning from malarious area.

• Inform patient that malaria prophylaxis should include protective clothing, insect repellent, and bed netting.

See Tell patient to immediately report psychiatric symptoms (such as acute anxiety, depression, restlessness, or confusion) and to stop taking drug.

• Caution patient to avoid driving and other hazardous activities because drug may cause dizziness.

• Instruct patient to have periodic ophthalmic exams, because drug may cause eye damage.

• Tell female patient to inform prescriber if she is pregnant.

• Advise female patient not to breastfeed while taking drug.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and tests mentioned above.