Pyrantel

Veterinary Products. Principal users of thiophene are the anthelmintics Pyrantel [15686-83-6] and Morantel [20574-50-9] (Pfizer) (59), based on 2-thiophenecarboxaldehyde and 3-methyl-2-thiophenecarboxaldehyde [5834-16-2], respectively. Tioconazole, one of a range of fungicidal products incorporating thiophene, has also found veterinary appHcations. 

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... 

The activity of pyrantel (Antimintii) is probably due to its ability to paralyze die helminth. Fbralysis causes die helminth to release its grip on die intestinal wall it is then excreted in die feces, pyrantel is used to treat round-worm and pinworm. Some patients receiving pyrantel may experience gastrointestinal side effects, such as nausea, vomiting, abdominal cramps, or diarrhea... 

Pyrantel—The patient can take this drug anytime without regard to meal or time of day. The patient may take the drug with milk or fruit juices. 

C,H2N02 372-09-8) see Cyclopentamine Levorphanol Pyrantel Sulindac cyanoacetyl chloride... 

C4H12N2 6291-84-5) see Oxyphencyclimine Pyrantel 9-(3-methylaminopropyl)anthracene (C,gH,jN) see Maprotiline... 

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. 

Figure 21.11A illustrates representative vesicle-attached recordings from a sensitive isolate (SENS), a pyrantel-resistant isolate (PYRR) and a levamisole-resistant isolate (LEVR) produced by 30 pM levamisole. There are differences in mean P-open values of receptors between sensitive and resistant isolates that would produce, on average, a reduction in the effect of the anthelmintic. However, one of the puzzling, but very consistent, observations is that there is a big range in the P-open values observed in different patches under the same experimental conditions in the same isolate (Fig. 21.1 IB). For example, the P-open values of the sensitive isolate were observed to vary between 0.090 and 0.003 at -50 mV with 30 pM levamisole, a 30-fold difference between the biggest and the smallest P-open...

Varady, M., Bjorn, H., Craven, J. and Nansen, P. (1997) In vitro characterization of lines of Oesophagostomum dentatum selected or not selected for resistance to pyrantel, levamisole and ivermectin. International Journal for Parasitology 27, 77-81. 

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