Halfan Side Effects

Generic Name: halofantrine

Please note - some side effects for Halfan may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

Side Effects of Halfan - for the Consumer

Halfan

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Halfan:

Cough; diarrhea; dizziness; headache; loss of appetite; nausea; stomach pain; vomiting.

Seek medical attention right away if any of these SEVERE side effects occur when using Halfan:

Severe allergic reactions (rash; hives; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); abnormal skin sensations; chest pain; dark urine; fast heartbeat; fatigue; pale color; seizures; shortness of breath; vision changes.

This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider. Call your doctor for medical advice about side effects. To report side effects to the appropriate agency, please read the Guide to Reporting Problems to FDA.

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Halfan Side Effects - for the Professional

Halfan

Normal Subjects

The following adverse events were reported in normal subjects given Halfan 1,000 mg to 1,500 mg in a single dosing course.

Gastrointestinal

Abdominal pain (10%), anorexia (5%), diarrhea (5%), nausea (10%), vomiting (10%).

Central Nervous System

Dizziness (5%), headache (5%).

Clinical Trials

In clinical trials involving 933 patients treated with three 500 mg doses (500 mg every 6 hours), the following clinical adverse events were reported.

There were no deaths or permanent disabilities thought related to drug toxicity. Five patients discontinued medication due to adverse events. Three patients vomited medicine repeatedly.

Though temporally related to drug administration, the relationship of the following serious adverse events to malaria or underlying illness as opposed to drug toxicity could not be established. Two patients had decreased consciousness; other serious adverse events reported during clinical trials included convulsions (3 cases), stomatitis (3 cases), moderately severe diarrhea (2 cases), pulmonary edema (1 case), tetany (1 case), hypertensive crisis (1 case), cerebrovascular accident (1 case).

The most frequently reported adverse events thought possibly— or probably—related to halofantrine were: Abdominal pain (8.5%), diarrhea (6.0%), dizziness (4.5%), vomiting (4.3%), nausea (3.4%), cough (3.0%), headache (3.0%), pruritus (2.6%), rigors (1.7%), and myalgias (1.3%). These events are also characteristic of malaria.

Pruritus was reported in a higher proportion of highly pigmented patients than in other patients.

Adverse events thought possibly—or probably—related to halofantrine affecting <1% of patients studied in the clinical trials included:

Body as a Whole

Fatigue, malaise.

Cardiovascular

Chest pain, palpitations, postural hypotension.

Dermatologic

Rash.

Gastrointestinal

Abdominal distention, anorexia, constipation, dyspepsia.

Mucous Membrane

Stomatitis.

Musculoskeletal

Arthralgia, back pain.

Central Nervous System

Asthenia, confusion, convulsions, depression, paresthesia, sleep disorder.

Renal

Urinary frequency.

Special Senses

Abnormal vision, tinnitus.

Laboratory

The most frequently noted laboratory abnormalities that occurred following drug administration in the clinical trials were decreased hematocrit, elevated hepatic transaminases, decreased and increased white blood cell counts, and decreased platelet counts. These alterations returned to normal limits within 2 to 3 weeks post-infection. The causal relationship of these changes to Halfan is unclear, as these laboratory abnormalities can also occur with acute malaria.

Postmarketing Experience

Halofantrine was marketed in Europe starting in 1988. The following additional adverse experiences have been reported in postmarketing surveillance outside the United States: Facial edema and urticaria (allergic/anaphylactic reactions) in rare cases.

Hemolysis/hemolytic anemia (including immune hemolytic anemia) which may compromise renal function have been reported in patients with malaria who have been treated with halofantrine. Hemolytic reactions may also be observed in patients with malaria in the absence of halofantrine.

Prolongation of QT interval has been reported. There have been rare reports of serious ventricular dysrhythmias sometimes associated with death. These cases have occurred particularly under certain conditions which include uses of doses higher than recommended, recent or concomitant treatment with mefloquine, or presence of pre-existing prolongation of QT interval.1

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Side Effects by Body System - for Healthcare Professionals

Cardiovascular

Higher risk may be associated with larger than recommended doses, previous or concurrent mefloquine treatment, preexisting QT interval prolongation, or concurrent administration of other QT interval-prolonging drugs. Prolonged QTc interval has been reported in up to 81% of adults treated with standard halofantrine doses and in 100% of patients treated with high doses (72 mg/kg). Prolonged QTc interval has been reported in 50% of children and prolonged PR interval has been reported in 38% of children (n=21). Females may have a higher risk of adverse cardiovascular effects.

It has been proposed that halofantrine prolongs repolarization by blocking HERG potassium channels.

Cardiovascular side effects have included QT interval prolongation, torsades de pointes, ventricular arrhythmias, and death. Chest pain and palpitations have been reported less than 1% of patients in clinical trials, and orthostatic hypotension has been reported in less than 1% to 33% of patients. Hypertensive crisis (1/933) and cerebrovascular accident (1/933) have been reported, although causality was not clearly established. Quinidine-like electrocardiographic changes have also been reported.

Gastrointestinal

Gastrointestinal (GI) side effects have included abdominal pain (8.5%), diarrhea (6%), vomiting (4.3%), and nausea (3.4%), although these symptoms may also occur with a malarial infection. Abdominal distention, anorexia, constipation, dyspepsia, and stomatitis have been reported in less than 1% of patients. GI upset has also been reported.

Hematologic

Hematologic side effects have included decreased hematocrit, decreased or increased white blood cells, decreased platelet counts, hemolysis, and hemolytic anemia. These reactions may also occur with a malaria infection.

Hypersensitivity

Hypersensitivity side effects have included allergic and anaphylactic reactions including facial edema and urticaria.

Dermatologic

Dermatologic side effects have included pruritus (2.6%) and rash (less than 1%).

Musculoskeletal

Musculoskeletal side effects have included rigors (1.7%), myalgia (1.3%), arthralgia (less than 1%), and back pain (less than 1%).

Nervous system

Nervous system side effects have included dizziness (4.5%) and headache (3%). Asthenia, confusion, convulsions, depression, paresthesia, and sleep disorder have been reported in less than 1% of patients.

Genitourinary

Genitourinary side effects have included urinary frequency (less than 1%).

Ocular

Ocular side effects have included abnormal vision (less than 1%).

Respiratory

Respiratory side effects have included cough (3%). Pulmonary edema has been reported (1/933); however, causality was not determined.

Other

Other side effects have included fatigue, malaise, and tinnitus in less than 1% of patients.

Hepatic

Hepatic side effects have included increased hepatic transaminases, which returned to normal within 2 to 3 weeks.

Renal

Renal side effects have included blackwater fever (acute intravascular hemolysis with acute renal failure and hemoglobinuria) requiring hemodialysis patients taking halofantrine for Plasmodium falciparum infections (n=2). Causality was not clearly established. One patient had a positive Coombs test.

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