Understanding Impavido (Miltefosine)
Impavido is an oral anti-parasitic drug, with its active ingredient being miltefosine. Approved by the FDA in 2014, it was the first oral therapy available in the United States for leishmaniasis. It is supplied as a capsule and is available by prescription only. Its development marked a significant advancement in treating parasitic diseases that are prevalent in tropical and subtropical regions.
How Does Impavido Work?
The precise mechanism of action for miltefosine is not fully known, but it is understood to be multifaceted. Research suggests that it disrupts the parasite's cellular functions, specifically by interfering with lipids like phospholipids and sterols within the cell membrane. This disruption affects the membrane's integrity and the parasite's mitochondrial function, ultimately leading to a form of programmed cell death (apoptosis) in the parasite.
What is Impavido Primarily Used For?
Impavido is FDA-approved for treating leishmaniasis in adults and adolescents aged 12 years or older who weigh at least 66 pounds (30 kg). Leishmaniasis presents in several forms, and Impavido is approved for:
- Visceral Leishmaniasis (VL): The most severe form, affecting internal organs like the spleen, liver, and bone marrow. Impavido is approved for VL caused by the Leishmania donovani parasite. Clinical trials in India have shown cure rates exceeding 94% for this condition.
- Cutaneous Leishmaniasis (CL): This form causes skin sores and is the most common type of leishmaniasis. Impavido is approved for CL caused by Leishmania braziliensis, Leishmania guyanensis, and Leishmania panamensis. Efficacy varies by region and parasite species, with cure rates in studies ranging from 48% to 82%.
- Mucosal Leishmaniasis (ML): A destructive form that affects the mucous membranes of the nose, mouth, and throat. Impavido is approved for ML caused by Leishmania braziliensis.
Other Significant Uses
Beyond its primary indication, Impavido has been used to treat other serious parasitic infections, often on a case-by-case basis through special access programs from the CDC. These include:
- Acanthamoeba Keratitis: A rare and severe eye infection that can cause permanent vision loss. Oral miltefosine has been used as an adjunctive or salvage therapy in refractory cases.
- Free-Living Ameba Infections: It is used for highly fatal brain infections like Primary Amebic Meningoencephalitis (PAM) caused by Naegleria fowleri and Granulomatous Amebic Encephalitis (GAE) caused by Balamuthia mandrillaris and Acanthamoeba species.
Administration
Impavido is administered orally and the duration of therapy is typically 28 consecutive days.
It is crucial to take the capsules whole with food to help reduce common gastrointestinal side effects like nausea and vomiting. Patients should complete the full course of therapy as prescribed by a healthcare professional, even if symptoms improve earlier.
Potential Side Effects and Warnings
Impavido carries a boxed warning for embryo-fetal toxicity. It is contraindicated in pregnancy and can cause fetal harm or death. Females of reproductive potential must have a negative pregnancy test before starting therapy and use effective contraception during treatment and for 5 months after the final dose.
Common side effects (occurring in ≥2% of patients) include:
- Nausea
- Vomiting
- Diarrhea
- Headache
- Decreased appetite
- Dizziness and drowsiness
- Abdominal pain
Serious but less common side effects can include:
- Severe skin reactions like Stevens-Johnson Syndrome
- Kidney or liver problems (requiring monitoring via blood tests)
- Low platelet counts (thrombocytopenia)
- Impaired male and female fertility
- Ocular complications like keratitis
Impavido vs. Other Leishmaniasis Treatments
| Treatment | Administration Route | Key Advantages | Key Disadvantages |
|---|---|---|---|
| Impavido (miltefosine) | Oral (capsule) | First and only oral option, easy to administer in outpatient settings. | Significant gastrointestinal side effects; high risk of fetal toxicity; potential for impaired fertility. |
| Amphotericin B (liposomal) | Intravenous (IV) infusion | Highly effective, particularly for visceral leishmaniasis. | Requires IV administration in a clinical setting; risk of infusion reactions and kidney toxicity. |
| Pentavalent Antimonials (e.g., Sodium Stibogluconate) | Intravenous (IV) or Intramuscular (IM) injection | Historically a primary treatment. | Requires parenteral administration; significant risk of cardiotoxicity, pancreatitis, and other side effects; resistance is an issue in some regions. |
| Azoles (e.g., Ketoconazole) | Oral | Oral administration. | Efficacy is mixed and often lower than other treatments; not a first-line therapy for most forms of leishmaniasis. |
Conclusion
Impavido (miltefosine) is a vital medication primarily used as the sole oral treatment for various forms of leishmaniasis and as a critical option for other rare and deadly amoebic infections. Its ease of administration has made it a cornerstone of therapy, especially in resource-limited settings. However, its use requires careful medical supervision due to a significant side effect profile, including common gastrointestinal issues and a severe risk of fetal harm, which necessitates strict precautions for patients of reproductive potential.
For more information, consult the official patient information at Impavido.com.
