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Update: January 2022
Forms and strengths
- 300 mg and 100 mg tablets
- 100 mg and 50 mg dispersible tablets, to be dispersed in 10 ml water
Dosage
- Child under 30 kg: 10 mg/kg (7 to 15 mg/kg) once daily
- Child 30 kg and over and adult: 5 mg/kg (4 to 6 mg/kg) once daily
- Maximum dose: 300 mg daily
|
Weight |
Daily dose |
300 mg |
100 mg |
|---|---|---|---|
|
5 |
35-75 |
− |
½ tab |
|
6 |
42-90 |
− |
1 tab |
|
7 |
49-105 |
− |
1 tab |
|
8 |
56-120 |
− |
1 tab |
|
9 |
63-135 |
− |
1 tab |
|
10 |
70-150 |
− |
1½ tab |
|
11 |
77-165 |
− |
1½ tab |
|
12 |
84-180 |
− |
1½ tab |
|
13 |
91-195 |
− |
2 tab |
|
14 |
98-210 |
− |
2 tab |
|
15 |
105-225 |
− |
2 tab |
|
16 |
112-240 |
− |
2 tab |
|
17 |
119-255 |
− |
2 tab |
|
18 |
126-270 |
− |
2 tab |
|
19 |
133-285 |
− |
2 tab |
|
20 |
140-300 |
− |
2 tab |
|
21 |
147-300 |
1 tab |
− |
|
22 |
154-300 |
1 tab |
− |
|
23 |
161-300 |
1 tab |
− |
|
24 |
168-300 |
1 tab |
− |
|
25 |
175-300 |
1 tab |
− |
|
26 |
182-300 |
1 tab |
− |
|
27 |
189-300 |
1 tab |
− |
|
28 |
196-300 |
1 tab |
− |
|
29 |
203-300 |
1 tab |
− |
|
|
|||
|
30-35 |
150 |
½ tab |
− |
|
36-45 |
300 |
1 tab |
− |
|
46-55 |
300 |
1 tab |
− |
|
56-70 |
300 |
1 tab |
− |
|
> 70 |
300 |
1 tab |
− |
Alternatively, 50 mg dispersible tablets may be used instead of ½ tablets of 100 mg.
Contra-indications, adverse effects, precaution
- Do not administer to patients with severe hepatic impairment.
- May cause:
- peripheral neuropathy;
- hepatotoxicity;
- hypersensitivity reactions, arthragias, optic neuritis, psychotic reactions, seizures and depression.
- Monitor closely:
- pregnant and breastfeeding women; patients with renal impairment, diabetes, malnutrition or HIV infection (increased risk of neuropathy);
- patients with alcohol dependence (increased risk of neuropathy and hepatotoxicity);
- patients with chronic hepatic disease or taking rifampicin or ≥ 35 years (increased risk of hepatotoxicity);
- patients taking antiseizure medications, benzodiazepines (risk of toxicity), warfarin (risk of bleeding). Dose adjustment may be required.
- For the management of adverse effects, see Appendix 17.
- Administer concomitantly pyridoxine (vitamin B6) to patients at risk of peripheral neuropathy (child: 5 to 10 mg once daily; adult: 10 mg once daily).
- Pregnancy and breastfeeding: no contra-indication. Administer pyridoxine to the mother (as above) and the breast-fed neonate or infant (5 mg once daily).
Monitoring
-
Symptomatic monitoring.
-
Liver function in patients with hepatic disease.
Patient instructions
- Take without food.
- 100 mg dispersible tablet should be dispersed in 10 ml water.
- Avoid alcohol during treatment.
Remarks
- For patients on drug-susceptible TB treatment, isoniazid is given as part of a fixed-dose combination.
- For the 6HRZEto regimen for drug-susceptible TB meningitis, the dose of isoniazid is 20 mg/kg once daily (max. 400 mg daily).
- Isoniazid is also used in the treatment of latent TB infection and multidrug-resistant TB treatment (at high dose - Hh).
Storage
– Below 25 °C