Pyrantel pamoate

Chemical Name E-1,4,5,6-tetrahydro-1-methyl-2-[2-(2-thienyl)vinyl]pyrimidine pamoate Common Name — 

Trade Name Manufacturer Country Year Introduced 

Thiophene-2-carboxaldehyde 1,2-Dlmethyl-l, 46,6-tetrahydropyrimidine Tartaric acid Pamoic acid 

A solution of 0.1 mol of each of thiophene-2-carboxaldehyde and 1,2-dimethyl-1,4,5,6-tetrahydropyrimidine in dimethyl carbonate (0.2 mol) is held at 27°C for 48 hours. The reaction mixture is then stripped to give a 65% yield of product as the free base. 

The base may be isolated as the tartrate as follows A portion of reaction mixture is added to a well stirred solution of tartaric acid in ethanol at 27°C. The mixture is stirred for two hours and the product recovered by filtration. The filter cake is washed with cold ethanol followed by ether and air-dried. MP 144°-147°C. 

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Niclosamide [50-65-7] (2/5-dichloro-4 -nitrosahcylanihde) has been commonly used against tapeworms in small animals (5). Although tapeworms (cestodes) are frequently refractory to anthelmintics highly active against other intestinal parasites, they are sensitive to niclosamide as well as pra2iquantel [55268-74-1] and epsirantel. Pyrantel pamoate [22204-24-6] is probably the most common animal wormer used in the 1990s. 

Pyrantel Pamoate. This dmg (10), C24H2qN20 S, cures pinworm infections and is close to 100% effective against A.scaris when given in a single dose (28,29). Pyrantel pamoate is also a principal dmg for the treatment of hookworm infections thus it is useful in patients with mixed worm infections. 

Since about 85% of the administered dose is passed unchanged in the feces of the patient, selective toxicity of the dmg can be attributed primarily to poor absorption. Side effects include abdominal pain, nausea, vomiting, diarrhea, loss of appetite, headaches, and vertigo or drowsiness. Skin rashes can also develop. Pyrantel pamoate is produced by Pfi2er, Inc., New York, New York. 

The tartrate salt is recrystallized by dissolving in hot methanol, filtering, adding hot ethanol to the filtrate and cooling. The product is collected and air-dried. MP 148°-150°C. A second crop is obtained from the filtrate for a total yield of 59%. The tartrate is then metathe-sized with pamoic acid (Merck Index 6867) to give pyrantel pamoate as the product. 

Dimethyl sulfoxide 1 -Dimethyl-1,4,5,6-tetrahydro-pyrimidine Pyrantel pamoate 3,5-Dinitrobenzoic acid Diatrizoate sodium Dioctyl sodium sulfosuccinate Docusate calcium... 

In both adults and pediatric patients older than 2 years of age, mebendazole 100 mg twice daily for 3 days is the treatment to use. An alternative agent is pyrantel pamoate (Antiminth). The stool should be checked within 2 weeks and the patient retreated when warranted. 

The mechanism of action by which pyrantel pamoate is effective lor the treatment of Necator americanu.% (hookworm) disease is... 

The answer is c. (Hardman, p 1022.) Pyrantel pamoate is an antihelminthic that acts primarily as a depolarizing neuromuscular blocker. In certain worms, a spastic neuromuscular paralysis occurs, resulting in the expulsion of the worms from the intestinal tract of the host. Pyrantel also exerts its effect against parasites via release of acetylcholine and inhibition of cholinesterase. 

Roundworms (nematodes) pinworm (Enterobius vermicularis) whipworm (Trichuris trichiura) Ascaris lumbricoides Trichinella spiralis Strongyloides stercoralis Hookworm (Necatoramericanus, and Ancylostoma duodenale) mebendazole or pyrantel pamoate mebendazole mebendazole or pyrantel pamoate mebendazole and thiabendazole thiabendazole mebendazole or pyrantel pamoate mebendazole or pyrantel pamoate... 

Pyrantel pamoate, a commonly-used anti-helmintic, provides another clinical example of exploiting the poor absorption of a drug... 

Pyrantel pamoate (Antiminth) is a agonist at the nicotinic acetylcholine receptor, and its actions result in depolarization and spastic paralysis of the helminth muscle. Its selective toxicity occurs primarily because the neuromuscular junction of helminth muscle is more sensitive to the drug than is mammalian muscle. This drug is administered orally, and because very little is absorbed, high levels are achieved in the intestinal tract. Less than 15% of the drug and its metabolites are excreted in urine. 

Pyrantel pamoate is active against several roundworms A lumbricoides, Ancylostoma duodenale, Necator americanus, and E. vermicularis. Pyrantel is an alternative drug of choice in treating infections with A lumbricoides, E. vermicularis (pinworms), and hookworms N. americanus and A. duodenale). It is not recommended for pregnant patients or for children under age 1 year. 

D. In the United States intestinal helminths produce mild disease with nonspecific findings. Piperazine or pyrantel pamoate may be used for the treatment of ascariasis. Mebendazole is an effective drug to be taken for 3 days. Thiabendazole is not used in this condition but is used commonly in strongyloidiasis. Albendazole at a single dose of 400 mg is the preferred mode of therapy. It is a... 

Other examples of pyrimidine-based pharmaceuticals include busipirone 1130, used to treat anxiety disorders, piribedil 1131 used for Parkinson s disease, epirizole 1132, a nonsteroidal antinflammatory (NSAID), pyrimethamine 1133, an antimalarial, minoxidil 1134, which is used for treating alopecia (male baldness), primidone 1135, which is used as an antiepileptic agent, and pyrantel pamoate 1136, which is used as an antiparasitic. 

Pyrantel pamoate (9.125), a tetrahydropyrimidine derivative, is a broad-spectrum antihelminthic active against pinworm and hookworm. This drug causes release of acetylcholine in the worm, producing stimulation and paralysis, leading to expulsion from the host s intestinal tract. 

Ascaris lumbricoides (roundworm) Albendazole or pyrantel pamoate or mebendazole Ivermectin, piperazine... 

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