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At least 19 recordsLinked to original sources
PubMed1989

Evaluation of albendazole, pyrantel, bephenium, pyrantel-praziquantel and pyrantel-bephenium for single-dose mass treatment of necatoriasis.

An effective drug for single-dose mass treatment of necatoriasis was sought by testing three drugs and two drug combinations in Ethiopian immigrants to Israel found to have light infections. The drugs tested sequentially in single-doses were pyrantel pamoate (20 mg kg-1, 81 subjects); bephenium hydroxynaphthoate (2.5-5 g, 65 subjects); combined pyrantel and bephenium (25 subjects); combined pyrantel (20 mg kg-1) and praziquantel (40 mg kg-1) (16 subjects); and albendazole (400 mg, 77 subjects). Follow-up under conditions without likelihood of reinfection was by one stool examination. Cure rates with albendazole, pyrantel-bephenium and pyrantel-praziquantel were 84, 80 and 81% respectively; these rates were significantly higher than the 49% found for bephenium and the 51% for pyrantel (P less than 0.05). Egg reductions in those not cured were pyrantel (22%), bephenium (6%), pyrantel-bephenium (34%), pyrantel-praziquantel (3%) and albendazole (6%). Albendazole was the most promising single drug treatment; unexpected was the high effectiveness of pyrantel-praziquantel in combination.

Adolescent↗
PubMed1981

Relative efficacies of pyrantel tartrate and pyrantel citrate against Oesophagostomum sp in swine.

The relative efficacies of pyrantel tartrate and of pyrantel citrate against Oesophagostomum sp in swine were evaluated in a controlled-critical study and the efficacy of pyrantel citrate in a field trial. In the controlled-critical study, pigs naturally infected with Oesophagostomum dentatum were either not treated or were treated with pyrantel citrate or pyrantel tartrate at a dosage of 510 mg of free pyrantel base/kg of feed. Six days later, the pigs were necropsied, adult O dentatum was recovered and counted, and fecal samples were examined for helminth eggs. The efficacies of pyrantel citrate and pyrantel tartrate were each 100% based on fecal egg counts and numbers of adults at necropsy. The field trial was conducted in a similar manner except that pyrantel citrate only was tested against a control group on the basis of fecal egg counts made both at the beginning and at the termination of the trial. In this study pyrantel citrate was found to reduce Oesophagostomum sp egg counts by 89.4%.

Animals↗
PubMed1996

The kinetic disposition of pyrantel citrate and pamoate and their efficacy against pyrantel-resistant Oesophagostomum dentatum in pigs.

The pharmacokinetic disposition of pyrantel after intravenous (i.v.) and oral (p.o.) administration as the citrate and p.o. administration as the pamoate salt was determined in pigs. Following i.v. administration pyrantel was quickly cleared from the bloodstream, exhibiting a terminal half-life of 1.75 +/- 0.19 h and a residence time (MRT) of 2.54 +/- 0.27 h. After p.o. administration as the citrate salt, the absorption time (MAT) of pyrantel was 2.38 +/- 0.25 h and although significant quantities of pyrantel were absorbed (mean bioavailability of 41%) the rapid clearance resulted in a MRT of only 4.92 +/- 0.36 h. By comparison, the significantly extended MAT of the less soluble pamoate salt resulted in reduced circulating concentrations and a significantly lower mean bioavailability of 16%. The poor efficacy of pyrantel citrate against nematodes inhabiting the large intestine of pigs is therefore suggested to result from insufficient quantities of drug passaging to the site of infection. When tested against pyrantel-resistant adult Oesophagostomum dentatum the mean efficacy of pyrantel citrate was only 23%, whereas the efficacy of the lesser absorbed pyrantel pamoate was 75%. These results indicate that for maximum activity pyrantel should be administered to pigs as the pamoate salt.

Administration, Oral↗
PubMed2000

The disposition of pyrantel in the gastrointestinal tract and effect of digesta flow rate on the kinetic behaviour of pyrantel in the pig.

Pigs consuming a diet with slow digesta transit time were orally administered with molar equivalent doses of pyrantel as the citrate and pamoate salt. At appropriate intervals pigs were killed and the quantitative-time distribution of pyrantel throughout the gut contents was determined. Compared with the citrate, there appeared to be greater quantities of the less soluble pamoate salt in the small and large intestine. An additional group of pigs fed on diets with "slow" or "fast" digesta transit time were orally treated with molar equivalent amounts of pyrantel as the citrate and pamoate salt and the respective kinetic disposition of pyrantel in peripheral plasma and quantitative excretion in faeces was determined. The diet type had little effect on pyrantel availability after administration of the less soluble pamoate salt. However, the maximum concentration of pyrantel in plasma was lower and there appeared to be greater quantities of pyrantel retained in the gut and excreted in faeces when the citrate salt was orally administered to pigs fed the "fast" compared to the "slow" diet. Since it is the quantity of pyrantel contained in the gut lumen which is believed to affect efficacy against gastrointestinal parasites, greater efficacy with this anthelmintic should be obtained when pigs are consuming a high fibre diet.

Administration, Oral↗
PubMed1994

Comparison of daily and monthly pyrantel treatment in yearling thoroughbreds and the protective effect of strategic medication of mares on their foals.

Studies on a Thoroughbred breeding farm in Ohio were done to: (1) compare the effects of daily administration of pyrantel tartrate feed pellets with monthly administration of a pyrantel pamoate paste to yearling horses (21 January-3 September); (2) assess the effects of daily pyrantel tartrate given strategically in spring/summer to foaling mares (1 April-16 August) and given for a prolonged period to barren mares (21 January-3 September); (3) determine if strategic medication of foaling mares with daily pyrantel tartrate protected their foals until weaning. There were no differences in cyathostome egg counts, pasture larval counts, body condition scores, or body weights of yearlings treated with daily pyrantel tartrate or monthly pyrantel pamoate. Both treatments failed to maintain fecal egg counts of yearlings below 100 eggs per gram (epg), and mean counts exceeded 400 epg (pyrantel pamoate) and 700 epg (pyrantel tartrate) in August and September, resulting in a sharp, but moderate increase in pasture infectivity in October. By contrast, prolonged or strategic use of daily pyrantel tartrate in mature horses were each highly effective in reducing pasture contamination and infectivity with cyathostome eggs and larvae respectively. Strategic medication of foaling mares provided protection of their foals until weaning and first treatment of foals was delayed until after weaning when mean strongyle counts exceeded 100 epg. Treatment of weanlings with pyrantel pamoate had little effect on egg counts. A comparative anthelmintic study with ivermectin, oxibendazole, and pyrantel pamoate confirmed earlier studies showing reduced efficacy of anthelmintics in young horses.

Administration, Oral↗
PubMed1993

Effects of pyrantel pamoate on adult and preadult Toxocara canis worms: an electron microscope and autoradiography study.

Adult as well as preadult Toxocara canis isolated from the intestine of a beagle were incubated for 2, 4, and 14 h in medium containing either different concentrations of pyrantel pamoate (23.6, 236, and 2360 micrograms/ml medium) or tritiated pyrantel pamoate (2.36 micrograms/ml medium). These incubations were performed to study the effects of pyrantel pamoate on the morphology of the parasitic nematodes and to obtain information concerning the mode of uptake, the distribution, and the total amount of pyrantel pamoate ingested by T. canis. The results of the ultrastructure studies indicate that the intestine, hypodermis, and muscle cells are the organs that are predominantly affected by the drug. Additionally, it turned out that the duration of the treatment, i.e., the incubation time, was more important in determining the efficacy of pyrantel pamoate against T. canis than was the concentration itself. Autoradiography studies revealed that the adult worms ingest the drug orally, whereas preadults absorb pyrantel pamoate mainly through the whole body surface. Finally, measurements of the total amount of pyrantel pamoate taken up by T. canis indicated that adult worms can limit or even reduce the ingestion of pyrantel for more than 4 h, but then ingest large amounts of the drug. Preadult worms, however, absorb the drug more or less continuously during the first 14 h through the cuticula, albeit in lower concentrations than the adults. The different experiments elucidate differences in the uptake of pyrantel pamoate as well as in the total amount of drug ingested or absorbed by adult or preadult worms, leading to the assumption that repeated treatment with lower concentrations will be more effective than high concentrations given only once.

Aging↗
PubMed1994

The action of pyrantel as an agonist and an open channel blocker at acetylcholine receptors in isolated Ascaris suum muscle vesicles.

The anthelmintic pyrantel is believed to act as an agonist at acetylcholine receptors on somatic muscle from the parasite Ascaris suum. This study aimed to confirm this mode of action of pyrantel. Single-channel recordings from muscle vesicles formed from the extrasynaptic region of the bag of somatic muscle cells of Ascaris suum were made using the patch-clamp technique. Pyrantel (0.03-100 microM) activated cation-selective channels with at least 2 conductance levels: main conductance 41 +/- 2.04 pS (mean +/- S.E., n = 28), smaller conductance 22.4 +/- 0.34 pS (mean +/- S.E., n = 8). The current/voltage plots showed a linear relationship. Detailed kinetic analysis revealed that activation of the receptor by pyrantel resulted in at least 2 distinct open and burst states and at least 3 distinct closed states. The mean open time of the channel, with 0.1 microM pyrantel, was 1.53 +/- 0.22 ms (mean +/- S.E., n = 7) at -75 mV. We have previously shown that acetylcholine activated channels with similar properties to the pyrantel-activated channels (Pennington, A.J. and R.J. Martin, 1990, J. Exp. Biol. 154, 201) confirming that pyrantel is an acetylcholine agonist. With high concentrations (100 microM) of pyrantel a sequence of rapid openings and closings of the channel was observed, indicating the presence of an open channel block. Previous experiments have shown that the anthelmintic levamisole, which also acts as an acetylcholine agonist on this preparation, induced channel block at hyperpolarised potentials with high concentrations (Robertson, S.J. and R.J. Martin, 1993, Br. J. Pharmacol. 108, 170). A comparison is made of the actions of the 3 agonists pyrantel, levamisole and acetylcholine at the nicotinic receptor in Ascaris muscle, and implications for the therapeutic use of the compounds are discussed.

Acetylcholine↗
PubMed1992

Comparative neuromuscular blocking actions of levamisole and pyrantel-type anthelmintics on rat and gastrointestinal nematode somatic muscle.

The basis for the comparative toxicity to parasitic nematodes and their mammalian hosts of the anthelmintics levamisole, pyrantel, and several related analogs on somatic nicotinic cholinergic transmission was examined. Measurements of muscle contractility and membrane potential were made using the isolated hemidiaphragm preparation of the rat and isolated axial muscle segments from the gastrointestinal nematode Haemonchus contortus. Pyrantel caused a dose- and time-dependent reduction of nerve-evoked twitches in the rat diaphragm. These effects were exacerbated by increasing the frequency of phrenic nerve stimulation from 0.5 to 50 Hz. Levamisole was less potent and the onset of its effects slower than pyrantel. Neither drug significantly affected twitches evoked from d-tubocurarine-blocked preparations following direct stimulation of the diaphragm. Twitch depression was reversed by washing, but not by application of physostigmine. In H. contortus, both drugs stimulated a spastic contraction and sustained paralysis in the concentration range of 1-10 microM, mimicking the action of nicotine. Neither nicotinic nor muscarinic antagonists blocked these responses. Moreover, neither nicotinic antagonists nor muscarinic agonists or antagonists had any independent effect on contractility of the parasite muscle segments. The blocking actions of levamisole and pyrantel on H. contortus axial muscle were associated with membrane depolarization at the muscle. In the rat-isolated hemidiaphragm, pyrantel, but not levamisole, depolarized end-plate regions of muscle fibers. d-Tubocurarine blocked the depolarizing action of pyrantel but not levamisole on rat-isolated hemidiaphragm. In axial muscle fibers of H. contortus, d-tubocurarine did not block the depolarizing actions of pyrantel, levamisole, or nicotine. 3-Bromo and 3-amino derivatives of levamisole were equipotent with and mimicked the actions of the parent compound on H. contortus axial muscle contractility. In the rat preparation, the 3-bromo derivative was more potent than levamisole or 3-amino-levamisole. 3-Amino-levamisole, but not 3-bromo-levamisole, depolarized muscle end-plate membrane in the rat diaphragm. Results of the present study are consistent with the following conclusions: (a) both levamisole and pyrantel block contractility of nematode axial muscle by causing sustained depolarization of the muscle membrane; (b) both drugs block neuromuscular transmission at the mammalian neuromuscular junction but their mechanisms appear to differ; (c) levamisole and pyrantel are more potent blockers of neuromuscular transmission in H. contortus than in the rat. These results suggest that potentially important pharmacological differences exist between nematode and mammalian somatic nicotinic receptors.

Animals↗
PubMed1995

Controlled efficacy study of the bioequivalence of Strongid C and generic pyrantel tartrate in horses.

The bioequivalence of Strongid C and generic pyrantel tartrate was determined in a controlled study using 30 horses with naturally acquired endoparasitic infections. Three horses were randomly allocated to each of ten replicates based on quantitative nematode and ascarid egg counts and fecal larvae culture results. Horses within each replicate were randomly assigned to one of three treatment groups. Horses in Treatment Group 1 received only oats; horses in Treatment Group 2 received generic pyrantel tartrate pellets (2.65 mg pyrantel tartrate kg-1) mixed with oats; horses in Treatment Group 3 were fed Strongid C pellets (2.65 mg pyrantel tartrate kg-1) mixed with oats. Horses were treated daily for a 30 day continuous treatment period. At the termination of the study the horses were necropsied and endoparasites recovered, identified, and enumerated. In all instances, no significant difference (P > 0.05) in mean numbers of parasites recovered existed between horses treated with generic pyrantel tartrate and Strongid C. Numbers of gastrointestinal parasites recovered from horses treated with generic pyrantel tartrate or Strongid C were shown to be significantly different (P < 0.05) from numbers of gastrointestinal parasites recovered from non-treated controls for the large strongyles (Strongylus vulgaris, S. edentatus, and Triodontophorus spp.), small strongyles (Cyathostomum spp., Cylicocyclus spp., and Cylicostephanus spp.) and fourth-stage Parascaris equorum. Numbers of adult P. equorum recovered from horses treated with Strongid C were also significantly different (P < 0.05) from those from non-treated controls. Numbers of adult P. equorum recovered from horses treated with generic pyrantel tartrate were not significantly different (P = 0.0761) from those from non-treated controls. The determination of bioequivalence was based upon the 95% confidence interval of the difference between the mean number of parasites recovered from horses treated with generic pyrantel tartrate and the mean number of parasites recovered from horses treated with Strongid C. For all instances in which the numbers of parasites recovered from horses treated with either Strongid C or generic pyrantel tartrate were significantly different from the numbers of parasites recovered from non-treated controls, bioequivalence was demonstrated.

Animal Husbandry↗
PubMed1970

Aspects of the pharmacology of a new anthelmintic: pyrantel.

1. The pharmacological properties of an anthelmintic, pyrantel, and some of its analogues have been described and compared with piperazine in a variety of vertebrate and helminth preparations.2. Pyrantel and its analogues in common with nicotine and decamethonium cause spastic paralysis in chicks and contracture of the chick semispinalis and toad rectus abdominis muscles.3. In the soleus and anterior tibialis muscles of the cat, pyrantel in large amounts caused a short-lived neuromuscular block that was preceded by initial depolarization.4. In preparations from cat and rat, pyrantel showed properties common to both competitive and depolarizing neuromuscular blocking drugs.5. Pyrantel blocked the contracture evoked by transmural stimulation and caused a marked contracture of the worm. Piperazine caused a gradually developing reduction in the responses to transmural stimulation and no contracture.6. Pyrantel and its analogues caused a slowly developing contracture of strip preparations of Ascaris, being more than 100 times more active than acetylcholine in this respect. Piperazine caused a relaxation of Ascaris strip preparations and in common with (+)-tubocurarine blocked the responses to acetylcholine and pyrantel analogues on this preparation.7. Pyrantel caused depolarization and increased spike discharge frequency in single muscle cells of Ascaris, these changes being accompanied by increase in tension. Piperazine, on the other hand, caused hyperpolarization and reduction in spike discharge frequency and relaxation, and antagonized the effects of pyrantel.

Animals↗
PubMed1990

Resistance to levamisole and cross-resistance between pyrantel and levamisole in Oesophagostomum quadrispinulatum and Oesophagostomum dentatum of pigs.

Two strains of Oesophagostomum spp., consisting of both O. quadrispinulatum and O. dentatum, were subjected to a controlled in vivo assay for resistance to levamisole and pyrantel by comparison with susceptible isolates. One strain (LEM) was recently isolated from a commercial herd, where sows showed high numbers of strongyle eggs in faeces within 2 weeks of farrowing and following treatment with levamisole at the manufacturer's recommended dose rate 1 week before farrowing. Levamisole had been used as the sole anthelmintic for treatment for at least 7 years on this farm. Treatment with pyrantel in this herd also indicated cross-resistance to this drug. A mixed population of O. quadrispinulatum and O. dentatum of this strain was subjected to controlled in vivo assays. Faecal egg count reduction (FECR) was found to be -573.3% (P greater than 0.05) and worm count reductions (WCR) of O. quadrispinulatum and O. dentatum were estimated as 44.5% (P greater than 0.05) and 96.4% (P less than 0.001), respectively. Treatment with pyrantel showed that cross-resistance existed to this drug, with FECR of 10.4% (P greater than 0.05) and WCR of 64.5% (P greater than 0.05) and 90.7% (P less than 0.05) for O. quadrispinulatum and O. dentatum, respectively. Another strain (VJ) was isolated from another commercial pig herd, which was dosed with pyrantel citrate four times a year for at least 8 years. This strain showed resistance to pyrantel, with FECR of 43.8% (P greater than 0.05) and WCR of 65.9% (P greater than 0.05) and 49.4% (P greater than 0.05) for O. quadrispinulatum and O. dentatum, respectively. However, both species were susceptible to levamisole. Our results suggested that selection with levamisole gave rise to levamisole resistance and automatically conferred resistance to pyrantel, whereas selection with pyrantel only resulted in resistance to this drug alone. These findings are discussed in relation to the location of the two species of Oesophagostomum in the large intestine of pigs and the mode of action of this class of anthelmintics.

Animals↗
PubMed2001

The anthelmintic pyrantel acts as a low efficacious agonist and an open-channel blocker of mammalian acetylcholine receptors.

Pyrantel is an anthelmintic which acts as an agonist of nicotinic receptors (AChRs) of nematodes and exerts its therapeutic effects by depolarizing their muscle membranes. Here we explore at the single-channel level the action of pyrantel at mammalian muscle AChR. AChR currents are elicited by pyrantel. However, openings do not appear in clearly identifiable clusters over a range of pyrantel concentrations (1-300 microM). The mean open time decreases as a function of concentration, indicating an additional open-channel block. Single-channel recordings in the presence of high ACh concentrations and pyrantel demonstrate that the anthelmintic acts as a high-affinity open-channel blocker. When analyzed in terms of a sequential blocking scheme, the calculated forward rate constant for the blocking process is 8x10(7) M(-1) x s(-1), the apparent dissociation constant is 8 microM at a membrane potential of -70 mV and the process is voltage dependent. Pyrantel displaces alpha-bungarotoxin binding but the concentration dependence of equilibrium binding is shifted towards higher concentrations with respect to that of ACh binding. Thus, by acting at the binding site pyrantel activates mammalian AChRs with low efficacy, and by sterical blockade of the pore, the activated channels are then rapidly inhibited.

Acetylcholine↗
PubMed1979

A clinical trial of oxantel and pyrantel against intestinal nematodes infections.

This study was conducted to determine the effect of oxantel/pyrantel tablets, oxantel suspension, pyrantel dry syrup and pyrantel tablets against T. trichiurus and A. lumbricoides infections. Twenty-four cases of mixed infections of T. trichiurus and A. lumbricoides were treated with oxantel/pyrantel tablets at a single dose of 20 mg/kg of body weight, and 49 cases of single infection of T. trichiurus were administered oxantel suspension at a single dose of 15 mg/kg of body weight. On the other hand, single infection of A. lumbricoides in 18 cases was administered pyrantel dry syrup at a single dose of 5 mg/kg of body weight. In the above 91 cases, the negative conversion rate and the egg reduction rate of egg out-put before and after the drug administration were examined by the cellophane thick smear method and Stoll's egg counting technique. A follow-up examination was carried out 3-4 weeks after the drug administration. Other 59 cases of single and mixed infection of T. trichiurus and A. lumbricoides were examined by the cellophane thick smear method only and administered pyrantel tablets at a single dose of 2.5 mg/kg of body weight. The results were summarized as follows: 1. The prevalence rates of T. trichiurus and A. lumbricoides infection in this study were 42.8% and 27.2% respectively by the cellophane thick smear method among 1,066 stool specimens. 2. The egg negative conversion rate and the egg reduction rate in the administration of oxantel/pyrantel tablets at a single dose of 20 mg/kg body weight were 75.0% and 97.8% respectively in T. trichiurus infection and 100% each in A. lumbricoides. 3. The egg negative conversion rate and the egg reduction rate in the administration of oxantel suspension at a single dose of 15 mg/kg body weight were 85.7% and 93.0% respectively in sinlge infection of T. trichiurus. 4. The egg negative conversion rate and the egg reduction rate in the administration of pyrantel dry syrup at a single dose of 5 mg/kg body weight were 100% each in single infection of A. lumbricoides. 5. The qualitative evaluation in cases of single and mixed infection of T. trichiurus and A. lumbricoides were by means of pyrantel tablets at a single dose of 2.5 mg/kg body weight, the cure being 100% against A. lumbricoides but 17.0% against T. trichiurus. 6. There were no undesirable side effects in this study and oxantel suspension and pyrantel dry syrup were well accepted and tolerated.

Journal Article↗
PubMed1978

Spectrophotometric determination of pyrantel tartrate in swine feeds by method of standard additions: collaborative study.

The spectrophotometric method for pyrantel tartrate in swine feeds was collaboratively studied. Twenty-seven laboratories assayed feeds containing 0.0103, 0.0965, and 0.7902% pyrantel tartrate. Repeatability (sigmao) and reproducibility (sigmax) standard deviations were: sigmao = 0.00068%, sigmax = 0.00105% (10% of grand mean) for 0.0103% pyrantel tartrate level; sigmao - 0.0065%, sigmax = 0.0090% (10% of grand mean) for 0.0965% pyrantel tartrate level; and sigmao = 0.0415%, sigmax = 0.0743% (10% of grand mean) for 0.7902% pyrantel tartrate level. The mean theoretical recovery values for feeds containing 0.0103, 0.0965, and 0.7902% were 100, 97, and 96%, respectively. The method was adopted as official first action for feeds or concentrates containing 0.0106-0.8811% pyrantel tartrate.

Animal Feed↗