Ethionamide (Eto) or prothionamide (Pto)

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    Update: January 2022

     

     

    Forms and strengths

    • 250 mg tablet (ethionamide or prothionamide)
    • 125 mg dispersible tablet (ethionamide), to be dispersed in 10 ml water

    Dosage

    • Child and adult: 15 to 20 mg/kg once daily
    • Maximum dose: 1000 mg daily

     

    Weight
    (kg)

    Daily dose
    (mg)

    250 mg
    tablet

    125 mg

    dispersible tablet

    5

    75-100

    1 tab

    6

    90-120

    1 tab

    7

    105-140

    1 tab

    8

    120-160

    1 tab

    9

    135-180

    1½ tab

    10

    150-200

    1½ tab

    11

    165-220

    2 tab

    12

    180-240

    2 tab

    13

    195-260

    2 tab

    14

    210-280

    2½ tab

    15

    225-300

    2½ tab

    16

    240-320

    2½ tab

    17

    255-340

    2½ tab

    18

    270-360

    2½ tab

    19

    285-380

    3 tab

    20

    300-400

    3 tab

    21

    315-420

    3 tab

    22

    330-440

    3 tab

    23

    345-460

    3 tab

    24

    360-480

    3 tab

    25

    375-500

    2 tab

    26

    390-520

    2 tab

    27

    405-540

    2 tab

    28

    420-560

    2 tab

    29

    435-580

    2 tab

     

    30-35

    500

    2 tab

    36-45

    500

    2 tab

    46-55

    750

    3 tab

    56-70

    750

    3 tab

    > 70

    1000

    4 tab

     

    Contra-indications, adverse effects, precautions

    • Do not administer to patients with severe hepatic impairment.
    • Administer with caution to patients with hepatic disease, diabetes or depression.
    • May cause:
      • frequently: gastrointestinal disturbances (abdominal or epigastric pain, diarrhoea, metallic taste, nausea and vomiting, stomatitis, etc.);
      • occasionally: endocrine disorders (gynecomastia, hypothyroidism), alopecia, depression, anxiety, psychosis, seizures, peripheral neuropathy, optic neuritis, hypoglycaemia, vestibular disorders, hepatotoxicity, hypersensitivity reactions.
    • For the management of adverse effects, see Appendix 17.
    • Avoid or monitor combination with isoniazid or cycloserine or terizidone (increased risk of neurotoxicity) and para-aminosalicylic acid (increased risk of gastrointestinal disturbances and hypothyroidism).
    • Administer concomitantly pyridoxine (vitamin B6); child: 1 to 2 mg/kg (usual range: 10 to 50 mg) once daily; adult: 100 mg once daily.
    • Pregnancy: CONTRA-INDICATED
    • Breastfeeding: administer pyridoxine to the mother (as above). Observe the breast-fed neonate or infant for adverse effects and supplement it with pyridoxine (1 to 2 mg/kg once daily).

    Monitoring

    • Symptomatic monitoring.
    • Liver function and thyroid function.

    Patient instructions

    • Take with food and/or at bedtime to limit gastrointestinal disturbances.
    • 125 mg tablets should be dispersed in 10 ml water.
    • Avoid alcohol during treatment.

    Remarks

    • To improve tolerance, start with a low dose (e.g. 250 mg daily in adults), then increase over 1 to 2 weeks to achieve the requested dose.
    • For the 6HRZEto regimen for drug-susceptible TB meningitis, the dose is 20 mg/kg once daily (max. 750 mg daily).

    Storage

     
    – 
     
    – 
    Below 25 °C