Pharmacokinetics and relative bioavailability of praziquantel in healthy water buffalo after oral and intramuscular administration

Investigation of pharmacokinetic interaction between ivermectin and praziquantel after oral administration in healthy dogs

The purpose of this study was to determine the pharmacokinetic interaction between ivermectin (0.4 mg/kg) and praziquantel (10 mg/kg) administered either alone or co-administered to dogs after oral treatment. Twelve healthy cross-bred dogs (weighing 18-21 kg, aged 1-3 years) were allocated randomly into two groups of six dogs (four females, two males) each. In first group, the tablet forms of praziquantel and ivermectin were administered using a crossover design with a 15-day washout period, respectively. Second group received tablet form of ivermectin plus praziquantel. The plasma concentrations of ivermectin and praziquantel were determined by high-performance liquid chromatography using a fluorescence and ultraviolet detector, respectively. The pharmacokinetic parameters of ivermectin following oral alone-administration were as follows: elimination half-life (t_1/2λz ) 110 ± 11.06 hr, area under the plasma concentration-time curve (AUC_0-∞ ) 7,805 ± 1,768 hr^. ng/ml, maximum concentration (C_max ) 137 ± 48.09 ng/ml, and time to reach C_max (T_max ) 14.0 ± 4.90 hr. The pharmacokinetic parameters of praziquantel following oral alone-administration were as follows: t_1/2λz 7.39 ± 3.86 hr, AUC_0-∞ 4,301 ± 1,253 hr^. ng/ml, C_max 897 ± 245 ng/ml, and T_max 5.33 ± 0.82 hr. The pharmacokinetics of ivermectin and praziquantel were not changed, except T_max of praziquantel in the combined group. In conclusion, the combined formulation of ivermectin and praziquantel can be preferred in the treatment and prevention of diseases caused by susceptible parasites in dogs because no pharmacokinetic interaction was determined between them.

Enantioselective Plasma Pharmacokinetic Study of a Novel Anti- Sichistosomiasis Agent P96 in Rat by Liquid Chromatography-tandem Mass Spectrometry

Background:

2-Cyclopentanecarbonyl-1,2,3,6,7,11b-hexahydro-pyrazino[2,1- a]isoquinolin- 4-one (P96), was found to be a novel drug candidate with one chiral center to treat schistosomiasis caused by Schistosoma japonicum. </P><P> Objective: To study pharmacokinetic characteristics, a simple, rapid and sensitive liquid chromatography- tandem mass spectrometry (LC-MS/MS) method was developed and fully validated for the quantification analysis of P96 in rat plasma.

Methods:

Chromatographic separation was performed on a C18 column with gradient eluted mobile phase composed of acetonitrile and water at a flow rate of 0.5 mL/min. Detection was performed on a triple-quadrupole tandem mass spectrometer using positive mode electrospray ionization in the multiple reactions monitoring (MRM) mode.

Results:

Excellent linearity was observed in the range of 3-900 ng/mL with the lower limit of quantification of 3 ng/mL in rat plasma for P96. The intra- and inter-day precisions exhibited less than 6.6%. Mean recoveries ranged from 96.9% to 102.4%. This method was applied to investigate the enantioselective differences on the pharmacokinetics between (R,S)-P96 and its enantiomers in rats after oral administration. The enantioselective differences of (R)-P96, (S)-P96 and (R,S)-P96 were found and compared.

Conclusion:

The established method was found to be accurate, precise, and sensitive and can be applied to investigate the stereoselective differences on pharmacokinetics between rac-P96 and its enantiomers.

Pharmacokinetics of praziquantel and pyrantel pamoate combination following oral administration in cats

Objectives The pharmacokinetics of praziquantel and pyrantel pamoate has never been reported in cats. The present study was designed to establish the plasma concentration-time profile and to derive pharmacokinetic data for a combined formulation of praziquantel and pyrantel in cats, after a single, oral administration. Methods Twenty-two clinically healthy adult cats were used, each receiving a single oral dose of praziquantel (8.5 mg/kg) and pyrantel (100 mg/kg). Blood samples were collected at regular time points up to 48 h post-dosing. Plasma concentrations of praziquantel and pyrantel were measured using a liquid chromatography-mass spectrometry-high-throughput screening method. Results Clinical examination of all cats did not reveal any side effects after oral administration of these medications. The terminal half-life for praziquantel and pyrantel was 1.07 and 1.36 h, respectively. Praziquantel peak concentration (Cmax) was 1140 μg/ml, reached at 1.22 h. The plasma concentrations of pyrantel after oral administration were low with a mean Cmax of 0.11 μg/ml, reached at a Tmax of 1.91 h. Pyrantel showed a very limited absorption as pamoate salt, suggesting permanence and efficacy inside the gastrointestinal tract, where the adult stages of most parasitic nematodes reside. Conclusions and relevance Pyrantel showed a very limited absorption as pamoate salt. Praziquantel was rapidly absorbed following oral administration and the concentrations achieved suggest that praziquantel could be an effective and safe medication in cats. Although some resistance problems are arising as a result of their long use, these anthelminthic products can still play a major role in parasitic control, especially in geographical areas where the high cost of newer treatments or necessity of parenteral administration could decrease the number of treated animals.