There are no available data on EGATEN use in pregnant women to inform a drug-associated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes. Reproductive studies in animals (rat and rabbits) have not shown a risk of increased fetal abnormalities with exposure to triclabendazole during organogenesis at doses approximately 0.3 to 1.6 times the maximum recommended human dose (MRHD) of 20 mg/kg based on body surface area comparison (see Data).
The estimated background risk of major birth defects and miscarriage for the indicated population are unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2%-4% and 15%-20%, respectively.
Embryo-fetal developmental toxicity studies revealed no malformations in rats and rabbits at doses up to 200 mg/kg/day and 20 mg/kg/day, respectively (approximately 1.6 times and 0.3 times the MRHD based on body surface area comparison, respectively). The animals were treated orally during organogenesis, starting on Day 6 of the pregnancy until Day 15 in rats and Day 18 in rabbits. Maternal toxicity was noted at doses greater than or equal to 100 mg/kg/day in rats and 10 mg/kg/day in rabbits, which was associated with lower fetus weights and delayed ossification. These findings were considered indicative of delayed physiological growth that was secondary to maternal toxicity. No increase in malformation or other abnormalities was observed at any dose level in either species.
There are no data on the presence of triclabendazole in human milk, the effects on the breastfed infant, or the effects on milk production. Published animal data indicate that triclabendazole is detected in goat milk when administered as a single dose to one lactating animal. When a drug is present in animal milk, it is likely that the drug will be present in human milk. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for EGATEN and any potential adverse effects on the breastfed infant from EGATEN or from the underlying maternal condition.
Safety and effectiveness of EGATEN has been established in pediatric patients aged 6 years and older.
Safety and effectiveness of EGATEN in pediatric patients below the age of 6 years have not been established.
Clinical studies of EGATEN did not include sufficient numbers of patients aged 65 and over to determine whether the elderly respond differently from younger patients. In general, dose selection for an elderly patient should be cautious, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.
8.6 Renal Impairment
EGATEN has not been studied in patients with renal impairment.
EGATEN has not been studied in patients with hepatic impairment.
The reported symptom of overdosage following ingestion of approximately 54 mg/kg of EGATEN (approximately 2.7 times the recommended dose) was nausea. The patient recovered following osmotic diuresis.
EGATEN (triclabendazole) tablet is an orally administered anthelmintic for immediate release. Triclabendazole is designated chemically as benzimidazole derivative, 6-chloro-5-(2, 3-dichlorophenoxy)-2-(methylthio)-1H-benzimidazole (triclabendazole). The molecular formula for triclabendazole is C14 H9 Cl3 N2 OS and the molecular weight is 359.65 g/mol. The chemical structure of triclabendazole is shown below:
Triclabendazole is a white or almost white, crystalline powder.
EGATEN tablets are pale red, speckled, capsule shaped, biconvex tablets, with imprint “EG EG” on one side and functionally scored on both sides. Each tablet contains 250 mg of triclabendazole.
Inactive Ingredients: colloidal silicon dioxide, iron oxide red, lactose monohydrate, maize starch, magnesium stearate, methylhydroxyethylcellulose.
Triclabendazole is an anthelmintic against Fasciola species [see Microbiology (12.4)].
Triclabendazole exposure-response relationships and the time course of pharmacodynamics response are unknown.
After oral administration of a single dose of 10 mg/kg triclabendazole with a 560-kcal meal to patients with fascioliasis, mean peak plasma concentrations (Cmax ) for triclabendazole, the sulfoxide and sulfone metabolites were 1.16, 38.6, and 2.29 μmol/L, respectively. The area under the curve (AUC) for triclabendazole, the sulfoxide and sulfone metabolites were 5.72, 386, and 30.5 μmol∙h/L, respectively.
Following oral administration of a single dose of triclabendazole at 10 mg/kg with a 560-kcal meal to patients with fascioliasis, the median Tmax for the parent compound and the sulfoxide metabolite was 3 to 4 hours.
Effect of Food
Cmax and AUC of triclabendazole and sulfoxide metabolite increased approximately 3-fold and 2-fold respectively when triclabendazole was administered as a single dose at 10 mg/kg with a meal containing a total of approximately 560 kcal (consisting of 2 cups of sweetened white coffee, a roll with cheese, and a roll with butter and jam). In addition, the sulfoxide metabolite Tmax increased from 2 hours in the fasted state to 4 hours in the fed state.
The apparent volume of distribution (Vd ) of the sulfoxide metabolite in fed patients is approximately 1 L/kg.
Protein-binding of triclabendazole, sulfoxide metabolite and sulfone metabolite in human plasma was 96.7%, 98.4% and 98.8% respectively.
The plasma elimination half-life (t1/2 ) of triclabendazole, the sulfoxide and sulfone metabolites in humans is approximately 8, 14, and 11 hours, respectively.
Based on in vitro studies, triclabendazole is primarily metabolized by CYP1A2 (approximately 64%) into its active sulfoxide metabolite and to a lesser extent by CYP2C9, CYP2C19, CYP2D6, CYP3A, and FMO. This sulfoxide metabolite is further metabolized primarily by CYP2C9 to the active sulfone metabolite and to a lesser extent by CYP1A1, CYP1A2, CYP1B1, CYP2C19, CYP2D6 and CYP3A4, in vitro.
No excretion data is available in humans. However, in animals, the drug is largely excreted via the biliary tract in the feces (90%), together with the sulfoxide and sulfone metabolite. Less than 10% of an oral dose is excreted in the urine.
The pharmacokinetics of EGATEN were not studied in patients with renal or hepatic impairment.
No dedicated pediatric pharmacokinetic studies were conducted. However, in one pharmacokinetic study of 20 patients, 7 children (ages 9 to 15 years) were dosed with triclabendazole 10 mg/kg single dose. AUC values of triclabendazole sulfoxide were 20% lower in these pediatric patients in the fed state than in the 13 patients above 15 years of age, but the difference was not statistically significant.
Drug Interaction Studies:
Clinical drug interaction studies have not been conducted for triclabendazole.
In Vitro Studies
Triclabendazole and its sulfoxide and sulfone metabolites have the potential to inhibit CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP3A at clinically relevant plasma concentrations, with the highest potential of inhibition on CYP2C19. No in vitro studies were conducted to assess the ability of triclabendazole and its metabolites to induce CYP enzymes. No in vitro studies were conducted to assess the ability of triclabendazole and its metabolites to induce or inhibit transporters.
Mechanism of Action
The mechanism by which triclabendazole exhibits its effect against Fasciola species is not fully elucidated. Studies in vitro and/or in infected animals suggest that triclabendazole and its active metabolites (sulfoxide and sulfone) are absorbed by the tegument of the immature and mature worms, leading to a decrease of the resting membrane potential, inhibition of tubulin function as well as protein and enzyme synthesis. These metabolic disturbances are associated with inhibition of motility, disruption of the surface as well as ultrastructure that includes inhibition of spermatogenesis and vitelline cells.
Triclabendazole and its metabolites are active against the immature and mature worms of Fasciola hepatica and Fasciola gigantica [see Clinical Studies (14)].
Studies in vitro and in vivo as well as case reports suggest a potential for development of resistance to triclabendazole.
The mechanism of resistance may be multifactorial that include changes in drug uptake/efflux mechanisms, the target molecules, and altered drug metabolism. The clinical significance of triclabendazole resistance in humans is not established.
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