Pharmacology and mechanism of action
Pyrvinium is a quaternary ammonium derivative of a cyanine dye with marked effect against Enterobius vermicularis.
The mechanism of action is not well known. The drug inhibits oxidative metabolism in the worms and interferes with the absorption of glucose in intestinal helminths. Since most intestinal worms are dependent on anaerobic carbohydrate metabolism, this may be an important action of the drug
[1].
Indications
Infections caused by Enterobius vermicularis. Pyrvinium is largely replaced today by more effective and safer drugs such as albendazole and mebendazole.
Side effects
Gastrointestinal disturbances such as nausea, vomiting, dyspepsia, indigestion and abdominal pain are frequent. Allergic reactions and photosensitivity have been reported. Pyrvinium stains the stool bright red and may stain clothing if vomiting occurs. Patients should be informed about this.
Preparations
Pyrvinium pamoate (embonate): 450 mg of the pamoate is equivalent to 300 mg of pyrvinium.
• Povanyl ® (Parke-Davis). Oral solution 10 mg pyrvinium per ml. Tablets 50 mg pyrvinium.
• Vanquin® (Parke-Davis). Oral solution 10 mg pyrvinium per ml. Tab pyrvinium.
References
1. Buchanan RA, Barrow WB, Heffelfinger JC, Kinkel AW, Smith TC, Turner JL (1974). Pyrvinium pamoate. Clin Pharmacol Ther, 16, 716–719.
Description
Pyrvinium is a tasteless, odorless, bright orange to black,
crystalline solid. It is insoluble in water or ether,
slightly soluble in chloroform, and soluble in
glacial acetic acid.
Uses
Pyrvinium Pamoate is a potent noncompetitive inhibitor of the androgen receptor, with the application towards prostate cancer treatment. Antihelmintic.
Definition
ChEBI: Pyrvinium pamoate is a naphthoic acid. It has a role as an anticoronaviral agent.
Indications
The cation is the active part of the compound.
Pyrvinium is used against pinworms (Enterobius).
brand name
Povan (Parke-Davis).
General Description
Odorless bright orange or orange-red to brownish red or almost black fluffy powder. Melting point 210-215°C. Insoluble in water. Tasteless.
Air & Water Reactions
Insoluble in water.
Reactivity Profile
PYRVINIUM PAMOATE is light sensitive. Incompatible with strong oxidizing agents, strong acids and bases .
Fire Hazard
Flash point data for PYRVINIUM PAMOATE are not available; however, PYRVINIUM PAMOATE is probably combustible.
Biochem/physiol Actions
Pyrvinium pamoate is a potent androgen receptor inhibitor. Androgen receptors (ARs) are nuclear hormone receptors/transcription factors that reside in the cytoplasm and activated by testosterone and dihydrotestosterone. AR inhibitors have potential therapeutic benefit in prostate cancer; competitive inhibitors and chemical castration methods have been discovered, but both therapies have undesirable side effects and/or resistance potential. A screen for non-competitive inhibitors was performed, resulting in the discovery of pyrvinium as an AR inhibitor. In comparison to competitive inhibitors, this compound does not bind to the ligand-binding domain of AR or block DNA occupancy by AR, but it inhibits AR-dependent gene expression via a distinct signaling mechanism. It is more potent than classical competitive AR antagonists and exhibits synergy with other AR inhibitors.
Side effects
Occasional adverse reactions are blood
dyscrasia and folic acid deficiency. Rare adverse
reactions are rash, vomiting, convulsion, shock,
photosensitivity, and headache.
