Pharmacokinetics and efficacy of long-term low-level administration of triclabendazole in urea molasses blocks against induced bovine and bubaline fasciolosis

Efficacy against Fasciola hepatica and the pharmacokinetics of triclabendazole administered by oral and topical routes

OBJECTIVE

To determine the efficacy of triclabendazole (TCBZ) against 28-day-old, early immature liver fluke in cattle and its pharmacokinetics following administration by the oral or topical (pour-on) route.

PROCEDURES

Cattle (n = 18) were infected with 500 TCBZ-susceptible liver fluke metacercariae and randomly allocated to three groups. At 28 days after infection, the groups were: (1) untreated controls; (2) treated with oral TCBZ at 12 mg/kg in combination with oxfendazole and selenium (TOS); (3) treated with pour-on TCBZ at 30 mg/kg in combination with abamectin (TA). Blood samples were taken immediately prior to treatment and serially after treatment to assess the plasma profile of TCBZ metabolites. Ten weeks after treatment all animals were slaughtered and total liver fluke counts, fluke egg counts and liver pathology were assessed.

RESULTS

Both the TOS and TA treatments resulted in significant reductions of 28-day-old liver fluke, as assessed by fluke counts and fluke egg counts at slaughter, and the reductions following TOS treatment were significantly greater than those following TA treatment. The blood profile of TCBZ metabolites in TOS-treated animals showed a significantly greater area under the plasma concentration time curve and a higher maximum observed concentration than those treated with TA. There was significantly less liver pathology in TOS-treated animals than in the TA-treated animals.

CONCLUSION

TCBZ administered orally at 12 mg/kg resulted in greater efficacy against 28-day-old, early immature liver fluke than was achieved by topical administration at 30 mg/kg. Plasma metabolites of TCBZ were higher and liver pathology was less in TOS-treated animals than in TA-treated animals.

Effect of Fascioliasis on the pharmacokinetic parameters of triclabendazole in human subjects

OBJECTIVES

To study the clinical efficacy of Triclabendazole (TCBZ) on Egyptian patients infected with Fasciola and understand the effect of Fascioliasis on the pharmacokinetics of TCBZ.

METHODS

The pharmacokinetics of TCBZ administered as a single oral dose (10 mg/kg) was investigated in both infected and parasite--free Egyptian subjects. After oral administration, TCBZ is metabolized to a sulphone and sulfoxide derivatives. The latter is responsible for the fasciolicidal activity of TCBZ, and it could be used as a marker of drug bioavailability. Blood samples were collected following the oral administration, and TCBZ sulfoxide plasma concentrations were determined by a sensitive and specific HPLC method.

RESULTS

Pharmacokinetic parameters (Cmax, AUC0-48, t1/2 and tmax) for TCBZ sulfoxide were calculated. In patients; the mean Cmax was 9.11 +/- 1.3 microg/ml, the mean AUC(0-48) was 91 +/- 10.5 microg h ml(-1), the mean t1/2 was 7.4 +/- 0.6 h, and the tmax was 3.0 +/- 0.4 h. In normal subjects, the mean Cmax was 8.48 +/- 0.92 microg/ml, the mean AUC(0-48) was 85 +/- 6.55 microg h ml(-1), the mean t1/2 was 6.2 +/- 0.357 h, and the tmax was 3 +/- 0.4 h. No significant difference could be detected in the patients as compared to normal subjects, which would suggest that Fascioliasis does not affect any of the studied parameters. No eggs in faeces could be detected following TCBZ treatment. Also, most of the clinical investigations showed significant decline back to the normal ranges post-treatment which indicates complete curing and high TCBZ efficacy.

CONCLUSION

Fasioliasis as an infective condition widely spread in Egypt has no significant effect on the pharmacokinetic parameters of the orally administered TCBZ and at the same time it is very effective against the parasite which strongly and safely suggests the use of this medication for the treatment of this infection.

Separation and characterization of synthetic impurities of triclabendazole by reversed-phase high-performance liquid chromatography/electrospray ionization mass spectrometry

A simple high-performance liquid chromatography/electrospray ionization mass spectrometry (HPLC/ESI-MS) method for the separation and characterization of impurities in the synthesis of triclabendazole has been developed. The analytical separation was achieved on a reversed-phase C18 column using acetonitrile and water (60:40, v/v) as mobile solvent at a flow-rate of 1.0 ml/min at 25 degrees C, and an UV detection at 230 nm. The on-line HPLC/ESI-MSn examinations were performed using ion trap analyzer with extraction ion chromatography (EIC) technique in positive or negative ion modes. The semi-preparative separation was performed with a reversed-phase column using methanol and water (75:25, v/v) as mobile solvent at a flow-rate of 4 ml/min at 25 degrees C, and an UV detection at 230 nm. Thus, two impurities were detected and identified as 5-chloro-6-(2,3,4-trichlorophenoxy)-2-methylsulfanyl-1H-benzoimidazole and 5-chloro-6-(2,3-dichlorophenoxy)-1-methyl-2-methylsulfanyl-1H-benzoimidazole. Meanwhile, some intermediates of impurity-1 in multi-step synthetic reactions, were tracked. Structural elucidation by 1D and 2D NMR and ESI-MSn was discussed.