Triclabendazole (Monograph)

Brand name: Egaten
Drug class: Anthelmintics
Chemical name: 6-chloro-5-(2, 3- dichlorophenoxy)-2-(methylthio)-1H-benzimidazole
Molecular formula: C₁₄H₉Cl₃N₂OS
CAS number: 68786-66-3

Medically reviewed by Drugs.com on Apr 10, 2024. Written by ASHP.

Introduction

Anthelmintic agent; benzimidazole derivative.

Uses for Triclabendazole

Fascioliasis

Treatment of fascioliasis caused by Fasciola hepatica or F. gigantica (liver flukes).

Drug of choice for treatment of fascioliasis; alternatives include bithionol (not commercially available in US) and nitazoxanide.

Paragonimiasis

Treatment of paragonimiasis^{† [off-label]} caused by Paragonimus westermani, P. mexicanus, or other Paragonimus (lung flukes).

Praziquantel usually considered drug of choice for treatment of paragonimiasis; alternatives include triclabendazole and bithionol (not commercially available in US).

Triclabendazole Dosage and Administration

Administration

Oral Administration

Administer orally with food.

The 250-mg tablets may be halved at the score line to provide 125-mg doses. If required dosage as tablets cannot be adjusted exactly, round dosage upwards.

Swallow tablets (whole or divided) with water. Alternatively, crush and mix with applesauce; stable for ≤4 hours after mixing with applesauce.

Dosage

Pediatric Patients

Fascioliasis

Oral

Children ≥6 years of age: Manufacturer recommends two 10-mg/kg doses given 12 hours apart.

Single 10-mg/kg dose has been used and is recommended by some clinicians; some evidence that cure rate is higher with a 2-dose regimen.

Paragonimiasis† [off-label]

Oral

Two 10-mg/kg doses given 12 hours apart or single 10-mg/kg dose. Cure rate may be higher with a 2-dose regimen.

Adults

Fascioliasis

Oral

Manufacturer recommends two 10-mg/kg doses given 12 hours apart.

Single 10-mg/kg dose has been used and is recommended by some clinicians; some evidence that cure rate is higher with a 2-dose regimen.

Paragonimiasis† [off-label]

Oral

Two 10-mg/kg doses given 12 hours apart or single 10-mg/kg dose. Cure rate may be higher with a 2-dose regimen.

Special Populations

Hepatic Impairment

No specific dosage recommendations.

Renal Impairment

Dosage adjustment probably unnecessary.

Geriatric Patients

Select dosage with caution because of greater frequency of decreased hepatic, renal, and/or cardiac function and concomitant disease or other drug therapy.

Cautions for Triclabendazole

Contraindications

Known hypersensitivity to triclabendazole, other benzimidazole derivatives, or any excipients in the preparation.

Warnings/Precautions

Prolongation of QT Interval

Studies in dogs suggest that triclabendazole can cause transient prolongation of QT interval corrected for rate (QT_c).

Monitor ECGs if triclabendazole used in patients with history of QT prolongation or symptoms compatible with long QT interval or in patients receiving drugs known to prolong QT interval.

Hepatic Effects

Transient increases in plasma concentrations of liver enzymes and total bilirubin reported in patients receiving triclabendazole for treatment of fascioliasis. In clinical studies, up to one-third of patients with fascioliasis had elevated liver enzymes at baseline and these generally improved post-treatment.

Specific Populations

Pregnancy

Data insufficient regarding use of triclabendazole in pregnant women to inform a drug-associated risk of major birth defects, miscarriages, or adverse maternal or fetal outcomes.

Reproduction studies in rats and rabbits receiving oral triclabendazole during organogenesis at doses approximately 1.6 and 0.3 times higher, respectively, than the maximum recommended human dosage (MRHD) of 20 mg/kg (based on body surface area comparison) have not shown increased risk of fetal abnormalities.

Some clinicians recommend that use in pregnant women be considered only for treatment of severe infections and only if potential benefits outweigh risks to the fetus.

Lactation

Not known whether triclabendazole distributes into human milk, affects breast-fed infants, or affects milk production. Distributed into milk in goats.

Consider benefits of breast-feeding and importance of triclabendazole to the woman; also consider potential adverse effects on breast-fed infant from the drug or underlying maternal condition.

Pediatric Use

Safety and efficacy not established in pediatric patients <6 years of age.

Geriatric Use

Insufficient data to determine whether patients ≥65 years of age respond differently than younger patients.

Hepatic Impairment

Not studied in patients with hepatic impairment.

Renal Impairment

Not studied in patients with renal impairment.

Common Adverse Effects

Abdominal pain reported in up to 56–93% of patients in clinical studies who received triclabendazole for treatment of fascioliasis; right upper quadrant abdominal pain and biliary colic in such patients attributed to expulsion of dead or dying worms from hepatobiliary system into GI tract.

Other adverse effects include hyperhidrosis, nausea, decreased appetite, headache, urticaria, diarrhea, vomiting, musculoskeletal chest pain, pruritus, increased liver function tests.

Drug Interactions

No formal drug interaction studies.

In vitro studies suggest triclabendazole and its sulfoxide and sulfone metabolites have potential to inhibit CYP isoenzyme 2C19 and, to a lesser extent, CYP1A2, 2A6, 2B6, 2C8, 2C9, 2D6, and 3A at clinically relevant plasma concentrations. No in vitro studies conducted to assess whether triclabendazole and its metabolites induce CYP enzymes.

Drugs Metabolized by Hepatic Microsomal Enzymes

Increased plasma concentrations of drugs that are CYP2C19 substrates. Effect on CYP2C19 substrates expected to be transient because of short triclabendazole elimination half-life and recommended duration of treatment.

If used concomitantly with a CYP2C19 substrate that requires therapeutic drug monitoring of systemic exposures, recheck plasma concentrations of the CYP2C19 substrate after triclabendazole treatment is finished.

Drugs That Prolong QT Interval

Because transient prolongation of QT_c reported in dogs receiving triclabendazole (see Prolongation of QT Interval under Cautions), monitor ECGs in patients receiving concomitant therapy with drugs that prolong the QT interval.

Triclabendazole Pharmacokinetics

Absorption

Bioavailability

Following a single 10-mg/kg dose of oral triclabendazole given with a 560-kcal meal, peak plasma concentrations of unchanged drug and active sulfoxide metabolite (triclabendazole sulfoxide) attained with 3–4 hours.

Food

Food enhances absorption of triclabendazole. Compared with administration in fasting state, administration with a 560-kcal meal results in threefold increase in peak plasma concentrations and twofold increase in AUC of triclabendazole and triclabendazole sulfoxide and increases time to peak plasma concentrations of the sulfoxide metabolite by 2 hours.

Distribution

Extent

Volume of distribution of sulfoxide metabolite is 1 L/kg.

Not known whether triclabendazole distributed into human milk; distributed into milk in goats.

Plasma Protein Binding

Triclabendazole, sulfoxide metabolite, and sulfone metabolite are approximately 97, 98, and 99% bound to plasma protein, respectively.

Elimination

Metabolism

In vitro studies indicate triclabendazole is principally metabolized (64%) to the active sulfoxide metabolite by CYP1A2 and, to a lesser extent, by CYP2C9, 2C19, 2D6, 3A, and flavin-containing monooxygenase (FMO). Triclabendazole sulfoxide is further metabolized to an active sulfone metabolite (triclabendazole sulfone), principally by CYP2C9 and, to a lesser extent, by CYP1A1, 1A2, 1B1, 2C19, 2D6, and 3A4.

Elimination Route

Data not available regarding elimination in humans.

Animal studies indicate oral triclabendazole largely excreted via biliary tract in feces (90%) as unchanged drug and sulfoxide and sulfone metabolites; <10% excreted in urine.

Half-life

Half-lives of triclabendazole, sulfoxide metabolite, and sulfone metabolite are approximately 8, 14, and 11 hours, respectively.

Special Populations

Not studied in patients with renal or hepatic impairment.

Stability

Storage

Oral

Tablets

<30°C in original container.

Tablets crushed and mixed with applesauce are stable for ≤4 hours.

Actions and Spectrum

Benzimidazole-derivative anthelmintic agent.
Narrow spectrum of anthelmintic activity. Active against certain trematodes (flukes), including F. hepatica and F. gigantica (liver flukes) and Paragonimus (lung flukes). Has minimal activity against nematodes, cestodes, and other trematodes.
Although mechanism of action of triclabendazole not fully elucidated, the drug binds to fluke β-tubulin and inhibits microtubule formation. In vitro studies and studies in infected animals suggest that triclabendazole and its active sulfoxide and sulfone metabolites are absorbed by the tegument of immature and mature Fasciola, leading to a decrease of resting membrane potential and inhibition of tubulin function as well as protein and enzyme synthesis. Because of its unique structure, triclabendazole is more capable of binding to β-tubulin of Fasciola than other benzimidazoles.
Resistance to triclabendazole reported in animal cases of Fasciola infection and also reported occasionally in human cases. Although clinical importance of triclabendazole resistance in human cases not established, treatment failures reported in patients with fascioliasis who received recommended regimens of oral triclabendazole may have been related to resistance to the drug. Resistance to triclabendazole may be multifactorial and could include changes in drug uptake/efflux mechanisms, mutations in target molecules, and/or altered drug metabolism in the organism.

Advice to Patients

Advise patients of importance of taking triclabendazole tablets with food. The tablets can be swallowed (whole or divided) with water. Alternatively, the tablets may be crushed and mixed with applesauce; crushed tablets mixed with applesauce are stable for ≤4 hours.
Importance of notifying clinician of persistent or worsening symptoms of infection.
Advise patients that ECG monitoring is needed if they have a history of prolongation of the QT_c interval, history of symptoms compatible with a long QT interval, or are receiving drugs that prolong the QT interval.
Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs, as well as any concomitant illnesses.
Importance of women informing their clinician if they are or plan to become pregnant or plan to breast-feed.
Importance of informing patients of other important precautionary information. (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.