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Ethionamide

Pronunciation

(e thye on AM ide)

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet, Oral:

Trecator: 250 mg [contains fd&c yellow #6 (sunset yellow)]

Brand Names: U.S.

  • Trecator

Pharmacologic Category

  • Antitubercular Agent

Pharmacology

Inhibits peptide synthesis; bacteriostatic

Absorption

Rapid, ~80% is rapidly absorbed from the GI tract

Distribution

Vd: 93.5 L; widely distributed into body tissues and fluids including liver, kidneys, and CSF

Metabolism

Prodrug; extensively hepatic to active and inactive metabolites

Excretion

Urine (<1% as unchanged drug; as active and inactive metabolites)

Time to Peak

Serum: 1 hour

Half-Life Elimination

2 to 3 hours

Protein Binding

~30%

Use: Labeled Indications

Treatment of tuberculosis and other mycobacterial diseases, in conjunction with other antituberculosis agents, when first-line agents have failed or resistance has been demonstrated

Contraindications

Hypersensitivity to ethionamide or any component of the formulation; severe hepatic impairment

Dosage

Oral:

Children: 15-20 mg/kg/day in 2-3 divided doses, not to exceed 1 g/day (CDC, 2009; WHO, 2008)

Adults: 15-20 mg/kg/day; initiate dose at 250 mg/day for 1-2 days, then increase to 250 mg twice daily for 1-2 days, with gradual increases to highest tolerated dose; average adult dose: 750 mg/day (maximum: 1 g/day in 3-4 divided doses)

Dosage adjustment in renal impairment: No dosage adjustment provided in manufacturer's labeling.

Dosage adjustment in hepatic impairment: Use is contraindicated in patients with severe hepatic impairment.

Administration

Neurotoxic effects may be prevented or relieved by the coadministration of pyridoxine (see Pyridoxine monograph for dosing). May be taken with or without meals. Gastrointestinal adverse effects may be decreased by administration at meals or bedtime, decreased dose, or giving antiemetics.

Dietary Considerations

Healthcare provider may recommend an increase in dietary intake of pyridoxine to prevent neurotoxic effects of ethionamide. Avoid alcohol.

Storage

Store at 20°C to 25°C (68°F to 77°F). Keep containers tightly closed.

Drug Interactions

Alcohol (Ethyl): May enhance the adverse/toxic effect of Ethionamide. Specifically, there may be a risk for a psychotic episode/reaction. Monitor therapy

CycloSERINE: Ethionamide may enhance the adverse/toxic effect of CycloSERINE. Monitor therapy

Isoniazid: Ethionamide may increase the serum concentration of Isoniazid. Monitor therapy

Adverse Reactions

Frequency not defined.

Cardiovascular: Orthostatic hypotension

Central nervous system: Depression, dizziness, drowsiness, headache, psychiatric disturbances, restlessness, seizure

Dermatologic: Acne, alopecia, photosensitivity, purpura, rash

Endocrine & metabolic: Gynecomastia, hypoglycemia, hypothyroidism or goiter, menstrual irregularities, pellagra-like syndrome

Gastrointestinal: Abdominal pain, anorexia, diarrhea, excessive salivation, metallic taste, nausea, stomatitis, vomiting, weight loss

Genitourinary: Impotence

Hematologic: Leukopenia, thrombocytopenia

Hepatic: Bilirubin increased, hepatitis, jaundice, liver function tests increased

Neuromuscular & skeletal: Arthralgia, peripheral neuritis

Ocular: Blurred vision, diplopia, optic neuritis

Respiratory: Olfactory disturbances

Miscellaneous: Hypersensitivity reaction

Warnings/Precautions

Disease-related concerns:

• Diabetes: Use with caution in patients with diabetes mellitus; may cause hypoglycemia.

• Hepatotoxicity: May cause hepatotoxicity; monitor liver function tests monthly.

• Porphyria: Use not recommended; porphyria-inducing in animal and in vitro studies (WHO, 2008).

• Thyroid dysfunction: Use with caution in patients with thyroid dysfunction; hypothyroidism (reversible) has been reported.

Concurrent drug therapy issues:

• Cycloserine: Use with caution in patients receiving cycloserine; seizures have been reported.

• Isoniazid: Use with caution in patients receiving isoniazid; temporarily increases isoniazid levels. Some cross-resistance has been reported if inhA mutation is present. (WHO, 2008).

Other warnings/precautions:

• Appropriate use: Drug-resistant tuberculosis develops rapidly if ethionamide is used alone; must administer with at least one other antituberculosis agent.

• Ethanol use: Instruct patients to avoid excessive ethanol; psychotic reaction may occur.

• Eye exams: Periodic eye exams are recommended.

Monitoring Parameters

Initial and periodic serum ALT and AST; blood glucose; TSH every 6 months; initial and periodic ophthalmic exams

Pregnancy Risk Factor

C

Pregnancy Considerations

Ethionamide crosses the placenta; teratogenic effects were observed in animal studies. Use during pregnancy is not recommended.

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience dyspepsia, nausea, diarrhea, parageusia, sialorrhea, lack of appetite, or weight loss. Have patient report immediately to prescriber signs of hepatic impairment, paresthesia, depression, vision changes, or signs of hypoglycemia (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for healthcare professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience and judgment in diagnosing, treating and advising patients.

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