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isoniazid
generic
Black Box Warnings .
Hepatotoxicity
severe hepatitis, incl. fatal, assoc. w/ isoniazid; most common in 1st 3mo but may occur at any time; monitor sx, interview pts qmo; AST/ALT at baseline, then periodically in pts 35 yo and older; D/C tx if LFTs >3-5x ULN or if s/sx hepatic injury, use alternative TB tx; if must restart wait until sx and LFTs resolve; restart at low dose, incr. gradually, and immediately D/C if any s/sx recurrent hepatic injury; defer preventive tx if acute hepatic dz; incr. risk if daily alcohol use, chronic hepatic dz, and IV drug use; incr. risk w/ age (highest risk in pts 50-64 yo, risk decr. in pts >65 yo); possible incr. risk in women, particularly black and Hispanic, and during post-partum period, consider more careful monitoring
Adult Dosing .
Dosage forms: TAB: 100 mg, 300 mg; SOL: 50 mg per 5 mL; INJ: 100 mg per mL
tuberculosis, active
- [5 mg/kg/dose PO/IM qd x6-18mo]
- Max: 300 mg/day; Alt: 5 mg/kg/dose PO/IM 5x/wk x6-18mo if directly observed tx; 15 mg/kg/dose PO/IM 1-3x/wk x6-18mo if directly observed tx, max 900 mg/dose; Info: part of multi-drug regimen; once weekly regimen given w/ rifapentine not 1st-line tx; once daily regimen given w/ rifapentine x4mo not 1st-line tx; give on empty stomach; duration varies by infection site/severity
tuberculosis, latent
- [monotherapy]
- Dose: 5 mg/kg/dose PO/IM qd x6mo or x9mo; Max: 300 mg/day; Alt: 15 mg/kg/dose PO/IM 2x/wk x6mo or x9mo if directly observed tx, max 900 mg/dose; Info: give x6mo if HIV-negative; not 1st-line tx; give on empty stomach
- [combo tx w/ weekly rifapentine (off-label)]
- Dose: 15 mg/kg/dose PO/IM qwk x3mo; Max: 900 mg/dose; Info: for non-pregnant pts; 1st-line tx; give on empty stomach
- [combo tx w/ rifampin (off-label)]
- Dose: 5 mg/kg/dose PO/IM qd x3mo; Max: 300 mg/day; Info: 1st-line tx; give on empty stomach
- [combo tx w/ daily rifapentine (off-label)]
- Dose: 300 mg PO qd x1mo; Info: for non-pregnant pts; not 1st-line tx; may self-admin; refer to WHO guidelines; give on empty stomach
renal dosing
- [no adjustment]
- renal impairment: no adjustment
- HD/PD: no adjustment; no supplement
hepatic dosing
- [see below]
- acute hepatic dz/previous isoniazid-associated hepatic injury: contraindicated
Peds Dosing .
- Dosage forms: TAB: 100 mg, 300 mg; SOL: 50 mg per 5 mL; INJ: 100 mg per mL
tuberculosis, active
- [1 mo-14 yo]
- Dose: 10-15 mg/kg/dose PO/IM qd x6-18mo; Max: 300 mg/day; Alt: 10-15 mg/kg/dose PO/IM 5x/wk x6-18mo if directly observed tx; 20-30 mg/kg/dose PO/IM 2x/wk x6-18mo if directly observed tx, max 900 mg/dose; Info: part of multi-drug regimen; give on empty stomach; duration varies by infection site/severity
- [15 yo and older]
- Dose: 5 mg/kg/dose PO/IM qd x6-18mo; Max: 300 mg/day; Alt: 5 mg/kg/dose PO/IM 5x/wk x6-18mo if directly observed tx; 15 mg/kg/dose PO/IM 1-3x/wk x6-18mo if directly observed tx, max 900 mg/dose; Info: part of multi-drug regimen; once weekly regimen given w/ rifapentine not 1st-line tx; once daily regimen given w/ rifapentine x4mo not 1st-line tx; give on empty stomach; duration varies by infection site/severity
tuberculosis, latent
- [monotherapy]
- Dose: 10-20 mg/kg/dose PO/IM qd x6mo or x9mo; Max: 300 mg/day; Alt: 20-40 mg/kg/dose PO/IM 2x/wk x6mo or x9mo if directly observed tx, max 900 mg/dose; Info: give x6mo if HIV-negative; not 1st-line tx; give on empty stomach
- [combo tx w/ weekly rifapentine, 2-11 yo (off-label)]
- Dose: 25 mg/kg/dose PO/IM qwk x3mo; Max: 900 mg/dose; Info: for non-pregnant pts; 1st-line tx; give on empty stomach
- [combo tx w/ weekly rifapentine, 12 yo and older (off-label)]
- Dose: 15 mg/kg/dose PO/IM qwk x3mo; Max: 900 mg/dose; Info: for non-pregnant pts; 1st-line tx; give on empty stomach
- [combo tx w/ rifampin (off-label)]
- Dose: 10-20 mg/kg/dose PO/IM qd x3mo; Max: 300 mg/day; Info: 1st-line tx; give on empty stomach
- [combo tx w/ daily rifapentine, 13 yo and older (off-label)]
- Dose: 300 mg PO qd x1mo; Info: for non-pregnant pts; not 1st-line tx; may self-admin; refer to WHO guidelines; give on empty stomach
tuberculosis, primary prevention
- [<5 yo]
- Dose: 10 mg/kg/dose PO/IM qd x3mo; Info: for PPD-negative pts exposed to TB; repeat PPD in 3mo; give on empty stomach
renal dosing
- [no adjustment]
- renal impairment: no adjustment
- HD/PD: no adjustment; no supplement
hepatic dosing
- [see below]
- acute hepatic dz/previous isoniazid-associated hepatic injury: contraindicated