Niclosamide is an anthelmintic medication, a class of drugs designed to treat worm infections. First synthesized in 1958, it is primarily used to address infections caused by various types of tapeworms. The medication is sold under brand names including Niclocide and is available only by prescription.
Medical Use for Parasitic Infections
Niclosamide is prescribed to treat specific tapeworm infestations in both adults and children. Its main application is against the beef tapeworm (Taenia saginata), the fish tapeworm (Diphyllobothrium latum), and the dwarf tapeworm (Hymenolepis nana).
The treatment regimen for beef and fish tapeworm infections typically involves a single 2-gram dose for adults. For children, the dosage is determined based on body weight. A second dose may be required after seven days to ensure the infection is fully cleared.
In the case of dwarf tapeworm infections, a longer treatment course is necessary. Patients are often directed to take the medication for a full seven days to prevent the infection from returning. Niclosamide is specific to tapeworms and is not effective against other types of parasitic worms, such as roundworms or pinworms. The killed worms are subsequently passed through the stool, though they are often destroyed within the intestine and may not be visible.
Mechanism of Action
The primary way niclosamide functions is by disrupting the energy metabolism of the tapeworm. It achieves this by a process called uncoupling of oxidative phosphorylation within the parasite’s mitochondria, which can be thought of as the cellular power plants. This action halts the production of adenosine triphosphate (ATP), a molecule that supplies the energy necessary for the worm’s metabolic processes. This targeted action affects the adult worms, but not their eggs.
In addition to disrupting energy production, niclosamide also inhibits the tapeworm’s ability to absorb glucose. Glucose is a simple sugar that serves as a fundamental source of nourishment for the parasite. By blocking this uptake, the medication further contributes to the starvation and eventual death of the worm. This dual action of cutting off both energy production and nutrient absorption makes it an effective agent against these specific parasites.
Administration and Side Effects
Niclosamide is administered orally in tablet form. For the medication to be effective, the tablets must be chewed thoroughly before being swallowed with a small amount of water. For young children who cannot chew the tablets, they should be crushed into a fine powder and mixed with a little water to form a paste.
Side effects associated with niclosamide are generally mild and tend to be concentrated in the gastrointestinal system. The most commonly reported issues include nausea, vomiting, and abdominal pain or cramping.
Other, less frequent side effects can include itchiness, dizziness, or a skin rash. While the medication is considered to have a good safety profile, it is important for patients to follow the prescribed dosage and administration instructions provided by their doctor. Severe adverse reactions are rare.
Potential for Drug Repurposing
Beyond its use as a treatment for parasites, niclosamide has attracted significant scientific interest for its potential in other medical areas. Researchers are actively investigating its properties as a broad-spectrum antiviral agent. Studies have explored its effects against various viruses, including research related to SARS-CoV-2, the virus that causes COVID-19.
The substance is also being examined for its potential as an anticancer agent. Laboratory studies have shown that it can affect multiple signaling pathways within cancer cells, which are communication networks that control cell growth and survival. By disrupting these pathways, niclosamide may help to inhibit tumor growth and survival.
Furthermore, niclosamide has demonstrated potential as an antibacterial and antifungal agent in preliminary research. It is important to understand that these applications are currently investigational. Niclosamide is not approved for the treatment of viral infections, cancer, or bacterial infections in humans, and extensive clinical trials are required to determine its safety and effectiveness for these other conditions.