Pyrantel is a nonabsorbed antihelmintic agent with activity against intestinal nematodes such as pinworms and roundworms. Pyrantel therapy has not been reported to cause serum aminotransferase elevations or clinically apparent liver injury.
Pyrantel (pi ran' tel) is a pyrimidine derivative which is believed to act by depolarizing the neuromuscular junction of nematodes, resulting in their paralysis and expulsion in stool. The drug is poorly absorbed from the intestine and is usually effective in a single dose. Pyrantel is currently available in the United States over-the-counter as tablets of 720 mg (250 mg pyrantel base) and in a suspension of 144 mg/mL (50 mg pyrantel base/mL) under the brand name Antiminth or Pin-X. It is recommended for pinworm infection due to Enterobius vermicularis and Ascaris lumbricoides. The typical dose in both adults and children is 11 mg/kg (up to 1 g) as a single dose, which can be repeated in two weeks. Pyrantel is widely used in veterinary medicine. Side effects are uncommon, mild and transient and include nausea, gastrointestinal upset and headache.
Pyrantel therapy has not been clearly associated with elevations in serum aminotransferase levels nor has its use been linked to cases of clinically apparent liver injury.
Mechanism of Injury
Pyrantel is minimally absorbed and given in single doses only, perhaps accounting for its lack of hepatotoxicity as currently used.
Outcome and Management
Pyrantel is usually well tolerated and clinically apparent liver injury has not been reported.
REPRESENTATIVE TRADE NAMES
Pyrantel – Generic, Antiminth®
Product labeling at DailyMed, National Library of Medicine, NIH
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References updated: 25 January 2014
Zimmerman HJ. Antihelminthics. Hepatic injury from antimicrobial agents. In, Zimmerman HJ. Hepatotoxicity: the adverse effects of drugs and other chemicals on the liver. 2nd ed. Philadelphia: Lippincott, 1999, pp. 626-8. (Expert review of hepatotoxicity of antihelmintics written in 1999; pyrantel is not discussed).
McCarthy J, Loukas A, Hotez PJ. Chemotherapy of helminth infections. In,
Brunton LL, Chabner BA, Knollman BC, eds. Goodman & Gilman’s the
pharmacological basis of therapeutics. 12th ed. New York: McGraw-Hill, 2011, pp.
1443-61. (Textbook of pharmacology and therapeutics).
Keiser J, Utzinger J. Efficacy of current drugs against soil-transmitted helminth infections: systematic review and meta-analysis. JAMA 2008; 299: 1937-48. PubMed Citation (Pyrantel pamoate is effective against A. Lumbricoides and possibly N. Americanus; side effects are mainly abdominal pain, nausea and dizziness).
St Georgiev V. Pharmacotherapy of ascariasis. Expert Opin Pharmacother 2001; 2: 223-39. PubMed Citation (Ascariasis can be treated with mebendazole, albendazole and pyrantel pamoate; a single dose of pyrantel has a cure rate of 95-100%; reported to cause mild serum enzyme elevations in children).
Van Riper G. Pyrantel pamoate for pinworm infestation. Am Pharm 1993; NS33: 43-5. PubMed Citation (Review: pyrantel is the only over-the-counter medication for pinworms [Enterobius vermicularis] and also has activity against the common roundworm [Ascaris lumbricoides]; recommended dose is 11 mg/kg given once or twice [2 weeks apart]; side effects are minimal and transient).
Drugs for parasitic infections. Treat Guidelines Med Ltr 2010; 8: 31-20. Not in PubMed (Brief description of drugs for parasitic infections in adults and children as well as a table of their major side effects; pyrantel can be helpful in treatment of pinworm [Enterobius] and whipworm [Trichostrongylus] infection; side effects can include gastrointestinal upset, headache, dizziness, rash and fever).
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