Niclosamide
[CAS# 50-65-7]

Identification

• Classification: API >> Antiparasitic drug >> Anti-fungal medicine
• Name: Niclosamide
• Synonyms: Bayluscid; 2',5-Dichloro-4'-nitrosalicylanilide; 2-Hydroxy-5-chloro-N-(2-chloro-4-nitrophenyl)benzamide; 5-Chloro-2'-chloro-4'-nitrosalicylanilide; 5-Chloro-N-(2-chloro-4-nitrophenyl)salicylamide
• Molecular Formula: C₁₃H₈Cl₂N₂O₄
• Molecular Weight: 327.12
• CAS Registry Number: 50-65-7
• EC Number: 200-056-8
• SMILES: C1=CC(=C(C=C1[N+](=O)[O-])Cl)NC(=O)C2=C(C=CC(=C2)Cl)O

Properties

• Solubility: 25 mM (ethanol), 10 mM (DMSO) (Expl.)
• Density: 1.6±0.1 g/cm³, Calc.^*
• Melting Point: 216-230 °C (Expl.)
• Index of Refraction: 1.709, Calc.^*
• Boiling Point: 424.5±45.0 °C (760 mmHg), Calc.^*
• Flash Point: 210.5±28.7 °C, Calc.^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07;GHS09 Warning
• Risk Statements: H302-H319-H400-H410
• Safety Statements: P264-P264+P265-P270-P273-P280-P301+P317-P305+P351+P338-P330-P337+P317-P391-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Eye irritation	Eye Irrit.	2	H319

• Transport Information: UN 3077

Discovery and Applications

Niclosamide is an anthelmintic drug primarily used to treat parasitic worm infections, specifically those caused by tapeworms. It is highly effective against a wide variety of tapeworm species, including *Taenia solium* (pork tapeworm), *Taenia saginata* (beef tapeworm), and *Diphyllobothrium latum* (fish tapeworm). Niclosamide is also employed in the treatment of other intestinal infections caused by parasitic worms, including hydatid disease caused by *Echinococcus* species.

The drug works by disrupting the energy production in the tapeworms, leading to their death. It acts by inhibiting the mitochondrial oxidative phosphorylation in the parasitic worms, causing the cells to lose their ability to generate energy. This disruption halts the worm’s metabolic processes, ultimately leading to the death of the parasite.

Niclosamide is typically administered orally in the form of tablets. It is often given as a single dose, although the exact dosage and duration may vary depending on the specific parasitic infection being treated. Because it is poorly absorbed from the gastrointestinal tract, niclosamide works primarily in the intestines, where the worms reside.

The medication is generally well-tolerated, with side effects being relatively uncommon. The most frequent side effects include mild gastrointestinal symptoms, such as nausea, vomiting, or abdominal discomfort. Serious side effects are rare but may include allergic reactions or skin rashes. Niclosamide is contraindicated in individuals with known hypersensitivity to the drug.

Although niclosamide is effective against tapeworm infections, it is not effective against other types of parasitic infections, such as those caused by roundworms or hookworms. As a result, it is typically used in combination with other medications to treat mixed parasitic infections if necessary. It is also used in combination with other therapeutic approaches, such as surgery, in cases of severe hydatid disease, which involves cysts formed by *Echinococcus* species in organs like the liver and lungs.

In addition to its use as an anthelmintic, niclosamide has been studied for potential anti-cancer properties. Preliminary research has suggested that it may have the ability to inhibit certain signaling pathways involved in the growth of cancer cells, although this area of study is still in its early stages. However, niclosamide is not currently approved for cancer treatment and is used exclusively for parasitic infections.

In summary, niclosamide is an effective anthelmintic medication primarily used to treat tapeworm infections. It works by inhibiting the energy production of the parasitic worms, leading to their death. While generally well-tolerated, the drug is mainly used for treating intestinal tapeworm infections and is not effective against other types of parasitic infections. It has also been investigated for its potential anti-cancer effects, but this application is not yet well-established.

References

2019. Niclosamide inhibits the cell proliferation and enhances the responsiveness of esophageal cancer cells to chemotherapeutic agents. Oncology Reports, 43(2).
DOI: 10.3892/or.2019.7449

2017. Niclosamide-conjugated polypeptide nanoparticles inhibit Wnt signaling and colon cancer growth. Nanoscale, 9(36).
DOI: 10.1039/c7nr01973d

2016. S100A4 drives non-small cell lung cancer invasion, associates with poor prognosis, and is effectively targeted by the FDA-approved anti-helminthic agent niclosamide. Oncotarget, 7(23).
DOI: 10.18632/oncotarget.8969