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

The combined effect of bromadiolone and ivermectin (iBr) in controlling both rodents and their fleas

Rodent pests not only cause severe agricultural loss but also spread zoonotic pathogens to human beings. Anticoagulant rodenticides are widely used to decrease the population densities of rodents but often lead to the spillover of ectoparasites because fleas and ticks may gather on surviving rodents. Therefore, it is necessary to kill fleas and ticks before culling rodents to minimize the risk of pathogen transmission. In this study, we used a mixture of ivermectin (an antiparasitic drug) and bromadiolone (an anticoagulant rodenticide) to control both rodent and flea/tick abundances. We found that in a laboratory test, 0.01% ivermectin bait was not lethal for greater long-tailed hamsters after 7 days of treatment, while 0.1% ivermectin bait was lethal for approximately 33% of treated rodents. In a field test, bait containing 0.001%, 0.005%, 0.01%, and 0.05% ivermectin decreased the number of fleas per vole of Brandt's voles to 0.42, 0.22, 0.12, and 0.2, respectively, compared with 0.77 in the control group, indicating that 0.01% ivermectin bait performed best in removing fleas. In another laboratory test, bait containing a 0.01% ivermectin and 0.005% bromadiolone mixture caused the death of all voles within 6-14 days after the intake of the bait. In the field test, the bait containing 0.01% ivermectin and 0.005% bromadiolone reduced the average number of fleas per vole to 0.35, which was significantly lower than the 0.77 of the control group. Our results indicate that a 0.01% ivermectin and 0.005% bromadiolone mixture could be used to control both rodents and fleas to minimize the spillover risk of disease transmission when using traditional rodenticides.

Pivotal role of permeability-glycoprotein in absorption of praziquantel into Dicrocoelium dendriticum parasite

Dicrocoelium dendriticum affects the livers of ruminants and causes several deleterious effects on animal health status. The aim of this study was to investigate the role of permeability-glycoprotein (P-gp) in absorption of praziquantel (PZQ) into D. dendriticum flukes by co-incubation with verapamil (VPL), an inhibitor of P-gp, under in vitro conditions. Mature flukes of D. dendriticum were collected from naturally infected sheep livers. The flukes were incubated with different concentrations of PZQ and VPL (50 and 100 μg/ml) in culture media and after several times of exposure (2, 6, 12, and 24 h), the concentration of PZQ absorbed in the parasites was measured by high-performance liquid chromatography. At 2-h post-incubation, the highest concentration of PZQ was noted as 0.92 µg/ml in the flukes treated with 100 μg/ml of each PZQ and VPL. After 24-h of exposure, VPL at all tested concentrations resulted in significant increase in absorption of PZQ into the parasite. Co-incubation of lancet flukes with VPL and PZQ roughly doubled the absorption of PZQ into them. Results of tegumental structures analysis by light microscopy confirmed higher efficacy of combination of VPL and PZQ. In conclusion, co-administration of VPL, especially at the concentration of 100 μg/ml, was able to increase PZQ uptake in Dicrocoelium flukes at all time points of the study.

Simultaneous Determination of Esafoxolaner, Eprinomectin, Praziquantel, BHT and Their Related Substances in a Topical Finished Product by a Single Reversed-Phase High-Performance Liquid Chromatography Method

The topical product with three active pharmaceutical ingredients (APIs), namely, esafoxolaner, eprinomectin and praziquantel has demonstrated its efficacy in the treatment of cats with mixed infections with ectoparasites and nematodes and cestodes. A reversed-phase high-performance liquid chromatography (RP-HPLC) method has been developed and validated for assay and determination of related substances peaks of three APIs including the assay of antioxidant butylated hydroxytoluene (BHT) in the finished product. Analytes were separated on a short Zorbax SB-C18 column (50 × 4.6 mm I.D., 5 μm particle size, pore size: 80 Å) with gradient elution at 40 °C column temperature. Analytes were detected at 245 nm for praziquantel, esafoxolaner, eprinomectin and their degradation products. BHT and eprinomectin degradation product 8a-oxo-B1a were detected at 280 nm. All analytes of interest were adequately separated within 40 min. The assay for praziquantel, esafoxolaner, eprinomectin and BHT was conducted against their corresponding external reference standards. The related substances peaks of each API were determined by peak area and relative response factor against total peak area of their corresponding API peak in sample solution. This method has been demonstrated to be accurate, robust, specific and stability indicating.

Development and validation of an LC-MS/MS method for the simultaneous quantification of milbemycin oxime and praziquantel in plasma: application to a pharmacokinetic study in cats

Introduction

Milbemycin oxime (MBO) and praziquantel (PZQ) have a broad spectrum of biological activity and are commonly used to treat the parasitic infection in the veterinary clinic. In this study, a fast and efficient LC-MS/MS method was established and validated for the simultaneous determination of MBO, PZQ, cis-4-hydroxylated-PZQ (C-4-OH-PZQ) and trans-4-hydroxylated-PZQ (T-4-OH-PZQ) and in cat plasma.

Methods

Extraction of analytes and internal standards from cat plasma by acetonitrile protein precipitation, allows rapid processing of large batches of samples. MBO, PZQ, C-4-OH-PZQ, T-4-OH-PZQ, and internal standard (IS) were eluted for 13.5 min on a C18 column with a 0.1% formic acid water/acetonitrile mixture as the mobile phase.

Results

Results showed that the method had good precision, accuracy, recovery, and linearity. The linearity range was 2.5-250 ng/mL for MBO, and 10-1000 ng/mL for PZQ, C-4-OH-PZQ, and T-4-OH-PZQ. The intra-day and inter-day precision CV values of the tested components were within 15%. The extraction recoveries of the four components ranged from 98.09% to 107.46%. The analytes in plasma remained stable for 6 h at room temperature, 26 h in the autosampler (4 °C), after freeze-thaw (-20°C) cycles, and 60 days in a -20°C freezer. Method sensitivity sufficed for assessing pharmacokinetic parameters of MBO, PZQ, C-4-OH-PZQ, and T-4-OH-PZQ in plasma samples with LLOQ of 2.5 ng/mL for MBO and 10 ng/mL for PZQ, C-4-OH-PZQ, and T-4-OH-PZQ.

Conclusion

In this study, a selective and sensitive LC-MS/MS method for the simultaneous quantification of MBO, PZQ, C-4-OH-PZQ, and T-4-OH-PZQ in cat plasma was developed and validated.This method had been successfully applied to evaluate the pharmacokinetics of MBO, PZQ, C-4-OH-PZQ, and T-4-OH-PZQ after a single oral administration of 8 mg MBO and 20 mg PZQ in cats.

Vitamins E and A increase the passing of the P-gp substrate ivermectin into the brain in mice

This study aimed to determine the effect of administration of oral vitamins A and E at different doses on plasma and brain concentrations of ivermectin in mice. The study was carried out on 174 Swiss Albino male mice aged 8-10 weeks. After leaving six mice for method validation, the remaining mice were randomly divided into seven groups with equal numbers of animals. Mice received ivermectin (0.2 mg/kg, subcutaneous) alone and in combination with low (vitamin A: 4000 IU/kg; vitamin E: 35 mg/kg) and high (vitamin A: 30 000 IU/kg; vitamin E: 500 mg/kg) oral doses of vitamins A and E. The plasma and brain concentrations of ivermectin were measured using high-performance liquid chromatography-fluorescence detector. We determined that high doses of vitamins A and E and their combinations increased the passing ratio of ivermectin into the brain significantly. The high-dose vitamin E and the combination of high-concentration vitamins E and A significantly increased the plasma concentration of ivermectin (P < 0.05). The high-dose vitamins E and A and their high-dose combination increased the brain concentration of ivermectin by 3, 2, and 2.7 times, respectively. This research is the first in vivo study to determine the interaction between P-gp substrates and vitamins E and A.

Synergistic effects of EP-1 and ivermectin mixture (iEP-1) to control rodents and their ectoparasites

BACKGROUND

Ectoparasites of rodents play significant roles in disease transmission to humans. Conventional poisoning potentially reduces the population densities of rodents, however, they may increase the ectoparasite loads on the surviving hosts. EP-1 has been shown to have anti-fertility effects on many rodent species, while ivermectin is effective in controlling ectoparasites. In this study, we examined the combined effects of EP-1 and ivermectin mixture (iEP-1) baits on rodents and their corresponding flea/tick loads.

RESULTS

In males, the weight of testis, epididymis, and seminiferous vesicle were reduced to less than 33%, 25%, and 17%, respectively, compared to the control group following administration of iEP-1 for 7 days. The weight of the uterus increased by approximately 75%. After 5 days of iEP-1 intake, all ticks were killed, whereas 94% of fleas on mice died after 3 days of bait intake. In the field test near Beijing, the flea index was reduced by more than 90% after 7 days of iEP-1 bait delivery. In a field test in Inner Mongolia, the weights of testis, epididymis, and seminiferous vesicle were significantly reduced by 27%, 32%, and 57%, respectively, 2 weeks after iEP-1 bait delivery. Approximately 36% rodents exhibited obvious uterine oedema accompanied by a weight increase of about 150%. The flea index was reduced by over 90%.

CONCLUSION

Our results indicated that iEP-1 is a promising treatment for reducing the abundance of both small rodents and their ectoparasites; this will be effective for managing rodent damage and transmission of rodent-borne diseases associated with fleas and ticks. © 2022 Society of Chemical Industry.

Control of cystic echinococcosis in the Middle Atlas, Morocco: Field evaluation of the EG95 vaccine in sheep and cesticide treatment in dogs

BACKGROUND

Cystic echinococcosis (CE) is an important cause of human morbidity and mortality worldwide, particularly in Morocco and other North African countries.

METHODOLOGY/PRINCIPAL FINDINGS

We investigated the potential of three strategies to reduce Echinococcus granulosus transmission: (1) 4-monthly treatment of dogs with praziquantel, (2) vaccination of sheep with the EG95 vaccine and (3) a combination of both measures. These measures were implemented during four consecutive years in different areas of the Middle Atlas Mountains in Morocco. The outcome of the interventions was assessed through hydatid cyst (viable and non-viable) counts in liver and lungs using necropsy or in vivo ultrasound examination of the liver. A total of 402 lambs were recruited for annual vaccination with the EG95 anti-E. granulosus vaccine and 395 similar lambs were selected as non-vaccinated controls. At approximately four years of age the relative risk (estimated as odds ratio) for vaccinated sheep to have viable hydatid cysts compared with non-vaccinated controls was 3% (9.37% of the vaccinated sheep were found infected while 72.82% of the controls were infected; p = 0.002). The number of viable cysts in vaccinated animals was reduced by approximately 97% (mean counts were 0.28 and 9.18 respectively; p<0.001). An average of 595 owned dogs received 4-monthly treatment during the 44 months trial, corresponding to 91% of the owned dog population. Approximately, 5% of them were examined for E. granulosus adult worms by arecoline purge or eggs in feces (confirmed by PCR). The proportion of infected dogs significantly decreased after treatment (12% versus 35%; p<0.001). Post-treatment incidence of re-infestation corresponded to a monthly risk of 4% (95% CI: 3-6%). Treatment of owned dogs on a 4-monthly basis did not reduce the level of transmission of E. granulosus to sheep, nor did it enhance the level of control generated by vaccination of sheep with EG95, possibly because of unowned dogs and wild canids were not treated.

CONCLUSIONS/SIGNIFICANCE

These data suggest that vaccination of sheep with EG95 has the potential to reduce the level of CE in Morocco and in other parts of the world with similar transmission dynamics. Under the epidemiological circumstances existing in the trial area, 4-monthly treatment of owned dogs with praziquantel was insufficient to have a major impact of E. granulosus transmission to sheep.

Pharmacokinetics of extended-release ivermectin microspheres after oral administration to healthy pigs

We compared the pharmacokinetics of ivermectin premix and ivermectin microspheres in pigs after single and multiple administration regimes. In the single-dose experiments, 24 piglets were randomly divided into three groups and given ivermectin at 0.3 mg/kg using (a) 1.0% ivermectin administered subcutaneously, (b) 0.25% ivermectin premix orally, and (c) 0.25% ivermectin microspheres orally. In the multiple-dose experiment, 6 pigs in two equal groups received ivermectin premix and microspheres orally at 0.3 mg/kg for 7 consecutive days to monitor the valley plasma levels. The plasma samples were detected by fluorescence high-performance liquid chromatography, and concentration-time data were fitted to a noncompartmental model. After oral administration of ivermectin microspheres at a single dose, the elimination rate constant (Kel), the half-life (t_1/2 ), the peak time (T_max ), the mean residence time (MRT), and the peak concentration (C_max ) were 0.012 ± 0.0031/hr, 59.94 ± 20.18 hr, 9.50 ± 0.93 hr, 55.96 ± 11.40 hr, and 37.75 ± 3.45 ng/ml, respectively. The C_max of microspheres was not statistically different (p > .05) compared with that of premix groups (39.81 ± 5.83 ng/ml). Moreover, the AUC of the microcapsule groups was increased from 1,129.76 ± 245.62 to 1,607.33 ± 343.35 hr ng/ml compared with the premix groups, and the relative bioavailability increased by an average of 17.53% after oral administration with ivermectin microspheres. Multiple-dose administration also indicated pigs fed with ivermectin microspheres can get a higher minimum steady-state concentration and a longer maintenance time than ivermectin premix.