Pyrantel

Identification

Summary

Pyrantel is an anthelmintic used to treat helminth infections.

Brand Names

Pronto Plus Pinworm, Pyral

Generic Name

Pyrantel

DrugBank Accession Number

DB11156

Background

Pyrantel is a pyrimidine-derivative anthelmintic agent for the oral treatment of various parasitic worm infections including ascariasis, hookworm infections, enterobiasis (pinworm infection), trichostrongyliasis, and trichinellosis ¹⁷.

Pyrantel was initially described in 1965 by researchers from Pfizer who sought cyclic amidines with suitable pharmacokinetic properties (specifically, duration of action) for use as an anthelmintic drug. Pyrantel is mainly available in formulations for dogs and cats as the embonate salt, containing a 34.7% pyrantel base ¹⁴.

Pyrantel is on the World Health Organization's List of Essential Medicines, which are the safest and most effective medicines required in a functioning health system ¹⁵, ¹⁶.

A depolarizing neuromuscular-blocking agent causing longstanding nicotinic receptor activation, resulting in spastic paralysis of susceptible nematodes (worms). Pyrantel has shown to be effective after a single dose ¹⁸.

In humans, it is administered as pyrantel pamoate ³,⁴,⁸,¹².

Type

Small Molecule

Groups

Approved, Vet approved

Structure

Similar Structures

Weight: Average: 206.31
Monoisotopic: 206.087769633
Chemical Formula: C₁₁H₁₄N₂S

Synonyms

Pirantel
Pyrantel
Pyrantelum

Pharmacology

Indication

For the treatment of enterobiasis including roundworm (ascariasis), pinworm (enterobius) and hookworm (strongyloides) and hookworm (ancylostoma) in the pyrantel pamoate form ⁸.

Pyrantel is available in various formulations for humans, dogs, and cats as the pamoate (US Pharmacopeia nomenclature) or embonate (European Pharmacopoeia nomenclature) salt, which contains 34.7% pyrantel base combined with pamoic acid ⁸. ¹⁴, ⁴.

Pyrantel pamoate (embonate) ingested orally is effective for removal and control of ascarid and hookworm infections in puppies and dogs (adult Toxocara canis, Toxascaris leonina, Ancylostoma tubaeforme, An. braziliense, Uncinaria stenocephala), cats (adult Toxocara cati, Toxa. leonina, An. caninum, An. braziliense, U. stenocephala), horses and ponies (adult and immature Parascaris equorum, adult Strongylus vulgaris, S. edentatus, S. equinus, Cyathostomes (Triodontophorus spp., Cyathostomum spp., Cylicodontophorus spp., Cylicocyclus spp., Cylicostephanus spp., Poteriostomum spp.), Oxyuris equi, Anoplocephala perfoliata), swine (adult Ascaris suum, Oesophagostomum dentatum), and humans (adult A. lumbricoides, Enterobius vermicularis, An. duodenale, Necator americanus) ¹⁴.

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Associated Conditions

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Pharmacodynamics

It has similar properties to both competitive and depolarizing neuromuscular blocking agents, which leads to the understanding of the paralytic effect of the drug has on parasites, ultimately resulting in the death of the parasite ¹⁶, ⁸.

Mechanism of action

By promoting the release of acetylcholine, inhibiting cholinesterase, and stimulating ganglionic neurons, pyrantel serves as a depolarizing neuromuscular blocking agent in helminths. This causes extensive depolarization of the helminth muscle membrane, resulting in tension to the helminth's muscles, leading to paralysis and release of their attachment to the host organism intestinal walls ⁸.

This action is unlike piperazine, which is a hyperpolarizing neuromuscular blocking agent that causes relaxation of the helminth muscles, leading to a subsequent detachment from the intestinal wall. Excretion of the parasites in the feces occurs by normal peristalsis ⁷.

Target	Actions	Organism
UG-protein coupled receptor 35	Not Available	Humans
NMuscarinic acetylcholine receptor M1	antagonist agonist	Humans

Absorption

Pyrantel is poorly absorbed from the GI tract of humans ⁸, ²¹.

Peak serum concentrations occur 1–3 hours after a single dose ¹⁷.

Volume of distribution

Not Available

Protein binding

Not Available

Metabolism

Pyrantel is administered orally. The poor solubility of the pamoate salt offers the advantage of reduced absorption from the gastrointestinal tract and allows the drug to reach and act against parasites in the large intestine. Metabolism of pyrantel is rapid ²². The absorbed drug is partly metabolized in the liver ²⁰.

Route of elimination

Approximately 50% of an oral dose is excreted unchanged in feces; 7% excreted in urine as unchanged drug and metabolites ¹⁷.

Half-life

In pigs, following intravenous administration, pyrantel exhibited a half-life of 1.75 +/- 0.19 h ⁵.

Clearance

Not Available

Adverse Effects

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Toxicity

Mild adverse effects include nausea, vomiting, diarrhea, headache, and dizziness ⁸.

LD50 in rats is 535 mg/kg ¹⁰.

Reported effects in humans in case of overdose include gastrointestinal disturbance, central nervous system effects, and superficial skin reactions. In one study, serum aspartate aminotransferase (AST) and serum alanine-aminotransferase (ALT) values were increased in approximately 2% of patients ¹⁹.

Pyrantel should be used with caution in patients with severe malnutrition or anemia. Supportive therapy is recommended for anemic, dehydrated, or malnourished patients before administration of the drug ¹².

Pyrantel pamoate has been placed in pregnancy category C. This refers to the fact that animal studies have revealed adverse effects on the fetus (teratogenic/embryocidal, or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the fetus ⁹.Data on the use of pyrantel pamoate in pregnant women are quite limited. In mass treatment programs for which the World Health Organization (WHO) has observed that the benefits of treatment outweigh the risks, WHO allows the use of pyrantel pamoate in the 2nd and 3rd trimesters of pregnancy, due to the fact that the effects of pyrantel on birth outcome are uncertain. The risk of treatment in pregnant women already known to have an infection needs to be balanced with the risk of disease progression if treatment were to be omitted ⁹. Individuals with liver disease are more susceptible to the toxicity in cases of pyrantel overexposure ⁹, ¹¹.

There are no data regarding the presence of pyrantel in breast milk. Pyrantel is poorly absorbed from the GI tract; therefore, excretion into breast milk may be minimal. Some experts recommend that a single dose of pyrantel therapy may be given to breastfeeding women ⁸.

Pathways

Not Available

Pharmacogenomic Effects/ADRs

Not Available

Interactions

Drug Interactions

This information should not be interpreted without the help of a healthcare provider. If you believe you are experiencing an interaction, contact a healthcare provider immediately. The absence of an interaction does not necessarily mean no interactions exist.

Drug	Interaction
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1,2-Benzodiazepine	The risk or severity of adverse effects can be increased when Pyrantel is combined with 1,2-Benzodiazepine.
Abacavir	Abacavir may decrease the excretion rate of Pyrantel which could result in a higher serum level.
Aceclofenac	Aceclofenac may decrease the excretion rate of Pyrantel which could result in a higher serum level.
Acemetacin	Acemetacin may decrease the excretion rate of Pyrantel which could result in a higher serum level.
Acetaminophen	Acetaminophen may decrease the excretion rate of Pyrantel which could result in a higher serum level.
Acetazolamide	The risk or severity of adverse effects can be increased when Acetazolamide is combined with Pyrantel.
Acetophenazine	The risk or severity of adverse effects can be increased when Acetophenazine is combined with Pyrantel.
Acetyldigitoxin	The risk or severity of Cardiac Arrhythmia can be increased when Pyrantel is combined with Acetyldigitoxin.
Acetylsalicylic acid	Acetylsalicylic acid may decrease the excretion rate of Pyrantel which could result in a higher serum level.
Aclidinium	Pyrantel may increase the central nervous system depressant (CNS depressant) activities of Aclidinium.

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Food Interactions

No interactions found.

Products

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Product Ingredients

Ingredient	UNII	CAS	InChI Key
Pyrantel citrate	1YXE665Z2S	5685-86-9	YJGGCARNRYGSPA-IPZCTEOASA-N
Pyrantel pamoate	81BK194Z5M	22204-24-6	AQXXZDYPVDOQEE-MXDQRGINSA-N
Pyrantel tartrate	SC82VF0480	33401-94-4	VWRCYAZJKNPEQR-NIEARKAZSA-N

Brand Name Prescription Products

Name	Dosage	Strength	Route	Labeller	Marketing Start	Marketing End	Region	Image
Jaa Pyral 35 Tablet 35mg	Tablet		Oral	Jaapharm Canada Inc.	1989-12-31	Not applicable

Over the Counter Products

Name	Dosage	Strength	Route	Labeller	Marketing Start	Marketing End
Combantrin Oral Suspension 50mg/ml	Suspension		Oral	Mcneil Consumer Healthcare Division Of Johnson & Johnson Inc	1973-12-31	Not applicable
Combantrin Tab 125mg	Tablet		Oral	Mcneil Consumer Healthcare Division Of Johnson & Johnson Inc	1973-12-31	Not applicable
CVS Pinworm Treatment	Suspension	144 mg/1mL	Oral	CVS Health	2016-12-15	Not applicable
DYNA PAR (WORM SUSPENSION) 125MG/5ML	Suspension		Oral	DYNAPHARM (M) SDN BHD	2020-09-08	Not applicable
Jaa Pyral 125 Tablet 125mg	Tablet		Oral	Jaapharm Canada Inc.	1998-11-27	Not applicable
Jaa Pyral P Oral Paste - 125mg/g	Paste		Oral	Jaapharm Canada Inc.	1995-12-31	Not applicable
Jaa Pyral S Suspension 50mg/76	Suspension		Oral	Jaapharm Canada Inc.	1995-12-31	Not applicable
Jamp-pyrantel Pamoate	Tablet		Oral	Jamp Pharma Corporation	2013-12-13	Not applicable
Jamp-pyrantel Pamoate Suspension	Suspension		Oral	Jamp Pharma Corporation	2014-03-25	Not applicable
Parasitexx	Suspension	144 mg/1mL	Oral	Dannso corp./d.b.a. Essential Products	2017-05-01	Not applicable

Mixture Products

Name	Ingredients	Dosage	Route	Marketing Start	Marketing End
HELMINTREL	Pyrantel (5 g) + Oxantel (5 g)	Suspension	Oral	2006-11-10	2018-06-01
HELMINTYC SUSPENSION	Pyrantel (5 g) + Oxantel (5 g)	Suspension	Oral	2006-11-10	2021-07-01
PAMOATO DE OXANTEL 250 MG/5ML + PAMOATO DE PIRANTEL 250 MG/5 ML SUSPENSIÓN.	Pyrantel pamoate (5 g) + Oxantel pamoate (5 g)	Suspension	Oral	2008-01-09	Not applicable
PAMOXPEN SUSPENSION ORAL	Pyrantel pamoate (5 g) + Oxantel pamoate (5 g)	Suspension	Oral	2010-02-03	Not applicable
PIRAXTEL® SUSPENSION	Pyrantel pamoate (5 g) + Oxantel pamoate (5 g)	Suspension	Oral	2007-04-09	Not applicable
VANPAR®	Pyrantel pamoate (5 g) + Oxantel pamoate (5 g)	Suspension	Oral	2015-03-05	2021-07-01

Chemical Identifiers

UNII: 4QIH0N49E7
CAS number: 15686-83-6
InChI Key: YSAUAVHXTIETRK-AATRIKPKSA-N
InChI: InChI=1S/C11H14N2S/c1-13-8-3-7-12-11(13)6-5-10-4-2-9-14-10/h2,4-6,9H,3,7-8H2,1H3/b6-5+
IUPAC Name: 1-methyl-2-[(E)-2-(thiophen-2-yl)ethenyl]-1,4,5,6-tetrahydropyrimidine
SMILES: [H]\C(=C(\[H])C1=NCCCN1C)C1=CC=CS1

References

General References

Aubry ML, Cowell P, Davey MJ, Shevde S: Aspects of the pharmacology of a new anthelmintic: pyrantel. Br J Pharmacol. 1970 Feb;38(2):332-44. [PubMed:5417856]
Rayes D, De Rosa MJ, Spitzmaul G, Bouzat C: The anthelmintic pyrantel acts as a low efficacious agonist and an open-channel blocker of mammalian acetylcholine receptors. Neuropharmacology. 2001 Aug;41(2):238-45. [PubMed:11489460]
Gokbulut C, Aksit D, Smaldone G, Mariani U, Veneziano V: Plasma pharmacokinetics, faecal excretion and efficacy of pyrantel pamoate paste and granule formulations following per os administration in donkeys naturally infected with intestinal strongylidae. Vet Parasitol. 2014 Sep 15;205(1-2):186-92. doi: 10.1016/j.vetpar.2014.06.026. Epub 2014 Jun 26. [PubMed:25015542]
Fasanmade AA, Akanni AO, Olaniyi AA, Fasanmade AA, Tayo F: Bioequivalence of pyrantel pamoate dosage forms in healthy human subjects. Biopharm Drug Dispos. 1994 Aug;15(6):527-34. [PubMed:7993990]
Bjorn H, Hennessy DR, Friis C: The kinetic disposition of pyrantel citrate and pamoate and their efficacy against pyrantel-resistant Oesophagostomum dentatum in pigs. Int J Parasitol. 1996 Dec;26(12):1375-80. [PubMed:9024887]
Li XQ, Bjorkman A, Andersson TB, Gustafsson LL, Masimirembwa CM: Identification of human cytochrome P(450)s that metabolise anti-parasitic drugs and predictions of in vivo drug hepatic clearance from in vitro data. Eur J Clin Pharmacol. 2003 Sep;59(5-6):429-42. Epub 2003 Aug 12. [PubMed:12920490]
Pharmacokinetics of praziquantel and pyrantel pamoate combination following oral administration in cats [Link]
Pyrantel Pamoate PDR [Link]
CDC for healthcare professionals [Link]
MSDS for pyrantel [Link]
Strongidpaste [Link]
Pyrantel Dosage [Link]
Pyrantel Pamoate [Link]
Pyrantel, Science Direct [Link]
Pediatric Ascaris Medication [Link]
Summary of product characteristics [Link]
Pyrantel Pamoate Monograph [Link]
Pyrantel MeSH NIH [Link]
Principles and Practice of Infectious Diseases [Link]
Pharmacotherapeutics For Advanced Practice Nurse Prescribers [Link]
Delmar Nurse's Drug Handbook 2012 Edition [Link]
MSD vet manual [Link]
DailyMed: Pyrantel pamoate oral suspension [Link]
INVIMA Product Information: Vanpar (pirantel pamoate/oxantel pamoate) oral suspension [Link]

External Links

KEGG Drug: D08451
KEGG Compound: C07409
PubChem Compound: 708857
PubChem Substance: 347827925
ChemSpider: 618121
RxNav: 8984
ChEBI: 8654
ChEMBL: CHEMBL1626223
ZINC: ZINC000000097996
Wikipedia: Pyrantel

AHFS Codes

08:08.00 — Anthelmintics

MSDS

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Clinical Trials

Clinical Trials

Phase	Status	Purpose	Conditions	Count
4	Completed	Treatment	Hookworm Infection	1
4	Completed	Treatment	Infection by Trichuris Trichiura	1
4	Recruiting	Treatment	Drug Resistance / Helminths Infection	1
Not Available	Recruiting	Prevention	Infection / Malnutrition	1

Pharmacoeconomics

Manufacturers

Not Available

Packagers

Not Available

Dosage Forms

Form	Route	Strength
Tablet	Oral	250 MG
Tablet, chewable	Oral
Tablet, chewable	Oral
Paste	Oral
Tablet, coated	Oral
Suspension	Oral	5 g
Tablet	Oral
Capsule, liquid filled	Oral
Suspension	Oral
Tablet, chewable	Oral	250 mg/1
Suspension	Oral	50 mg/1mL
Tablet	Oral	250 mg/1
Suspension	Oral	144 mg/1mL
Tablet, coated	Oral
Tablet	Oral
Liquid	Oral	5 mL/250mL
Powder	Not applicable	1 g/1g
Suspension	Oral	5 g/100mL
Tablet	Oral	180 mg/1
Tablet, film coated	Oral
Syrup	Oral
Suspension	Oral	125 mg/5ml
Tablet	Oral	360 mg
Suspension	Oral	250 mg/5ml
Suspension	Oral
Tablet	Oral	125 mg

Prices

Not Available

Patents

Not Available

Properties

State

Solid

Experimental Properties

Property	Value	Source
water solubility	insoluble in water	MSDS

Predicted Properties

Property	Value	Source
Water Solubility	0.118 mg/mL	ALOGPS
logP	2.69	ALOGPS
logP	1.96	ChemAxon
logS	-3.2	ALOGPS
pKa (Strongest Basic)	10.71	ChemAxon
Physiological Charge	1	ChemAxon
Hydrogen Acceptor Count	2	ChemAxon
Hydrogen Donor Count	0	ChemAxon
Polar Surface Area	15.6 Å²	ChemAxon
Rotatable Bond Count	2	ChemAxon
Refractivity	61.81 m³·mol^-1	ChemAxon
Polarizability	23.32 Å³	ChemAxon
Number of Rings	2	ChemAxon
Bioavailability	1	ChemAxon
Rule of Five	Yes	ChemAxon
Ghose Filter	Yes	ChemAxon
Veber's Rule	Yes	ChemAxon
MDDR-like Rule	No	ChemAxon

Predicted ADMET Features

Not Available

Spectra

Mass Spec (NIST)

Not Available

Spectra

Spectrum	Spectrum Type	Splash Key
Predicted GC-MS Spectrum - GC-MS	Predicted GC-MS	Not Available
Predicted MS/MS Spectrum - 10V, Positive (Annotated)	Predicted LC-MS/MS	Not Available
Predicted MS/MS Spectrum - 20V, Positive (Annotated)	Predicted LC-MS/MS	Not Available
Predicted MS/MS Spectrum - 40V, Positive (Annotated)	Predicted LC-MS/MS	Not Available
Predicted MS/MS Spectrum - 10V, Negative (Annotated)	Predicted LC-MS/MS	Not Available
Predicted MS/MS Spectrum - 20V, Negative (Annotated)	Predicted LC-MS/MS	Not Available
Predicted MS/MS Spectrum - 40V, Negative (Annotated)	Predicted LC-MS/MS	Not Available

Targets

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Details1. G-protein coupled receptor 35

Kind: Protein
Organism: Humans
Pharmacological action: Unknown

General Function: G-protein coupled receptor activity
Specific Function: Acts as a receptor for kynurenic acid, an intermediate in the tryptophan metabolic pathway. The activity of this receptor is mediated by G-proteins that elicit calcium mobilization and inositol pho...
Gene Name: GPR35
Uniprot ID: Q9HC97
Uniprot Name: G-protein coupled receptor 35
Molecular Weight: 34071.89 Da

References

Zhao P, Sharir H, Kapur A, Cowan A, Geller EB, Adler MW, Seltzman HH, Reggio PH, Heynen-Genel S, Sauer M, Chung TD, Bai Y, Chen W, Caron MG, Barak LS, Abood ME: Targeting of the orphan receptor GPR35 by pamoic acid: a potent activator of extracellular signal-regulated kinase and beta-arrestin2 with antinociceptive activity. Mol Pharmacol. 2010 Oct;78(4):560-8. doi: 10.1124/mol.110.066746. Epub 2010 Jul 22. [PubMed:20826425]

Details2. Muscarinic acetylcholine receptor M1

Kind: Protein
Organism: Humans
Pharmacological action: No
Actions: Antagonist
Agonist

General Function: Phosphatidylinositol phospholipase c activity
Specific Function: The muscarinic acetylcholine receptor mediates various cellular responses, including inhibition of adenylate cyclase, breakdown of phosphoinositides and modulation of potassium channels through the...
Gene Name: CHRM1
Uniprot ID: P11229
Uniprot Name: Muscarinic acetylcholine receptor M1
Molecular Weight: 51420.375 Da

References

Rayes D, De Rosa MJ, Spitzmaul G, Bouzat C: The anthelmintic pyrantel acts as a low efficacious agonist and an open-channel blocker of mammalian acetylcholine receptors. Neuropharmacology. 2001 Aug;41(2):238-45. [PubMed:11489460]

Enzymes

Details1. Cytochrome P450 4A11

Kind: Protein
Organism: Humans
Pharmacological action: Unknown
Actions: Substrate

General Function: Leukotriene-b4 20-monooxygenase activity
Specific Function: Catalyzes the omega- and (omega-1)-hydroxylation of various fatty acids such as laurate, myristate and palmitate. Has little activity toward prostaglandins A1 and E1. Oxidizes arachidonic acid to 2...
Gene Name: CYP4A11
Uniprot ID: Q02928
Uniprot Name: Cytochrome P450 4A11
Molecular Weight: 59347.31 Da

References

Li XQ, Bjorkman A, Andersson TB, Gustafsson LL, Masimirembwa CM: Identification of human cytochrome P(450)s that metabolise anti-parasitic drugs and predictions of in vivo drug hepatic clearance from in vitro data. Eur J Clin Pharmacol. 2003 Sep;59(5-6):429-42. Epub 2003 Aug 12. [PubMed:12920490]

Drug created on December 03, 2015 16:51 / Updated on May 06, 2021 06:19

Pyrantel

Identification

Structure for Pyrantel (DB11156)

Pharmacology

Interactions

Products

Categories

Chemical Identifiers

References

Clinical Trials

Pharmacoeconomics

Properties

Spectra

Targets

References

References

Enzymes

References